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Most Asterids show a combination of derived floral characteristics. Fused petals, reduced numbers of stamens attached to the corolla, and zygomorphic flowers are all commonly encountered themes within the Asterids. However, the only morphological synapomorphy that all Asterids share is the presence of a single integument layer on the embryo. As currently recognized, the Asterids contain some plants formerly classified as Rosids or Dilleniids. In the family Asteraceae, perhaps the most modified inflorescences exist; the superficial "flowers" of many Asteraceae are actually a disk of many crowded, radially symmetric flowers, surrounded by a ring of asymmetric, ligulate flowers resembling petals. The orders of Asterids have been subgrouped by the APG (1998) and others into groups known as Euasterid I and Euasterid II, with the orders Cornales and Ericales falling basal to these clades. Although the families are herein listed in pseudo-taxonomic order according to this arrangement, the placement of some orders within these groups is subject to change, and relationships between orders within these groups is poorly resolved.
Purple denotes orders containing families covered in class; green denotes orders photographically represented but not covered in Biology 414. Click on the tree to skip directly to a given order.
Asterid families covered in class: Cornales: Cornaceae (Dogwood Family) Ericales: Ericaceae (Heath Family) Polemoniaceae (Phlox Family) Sarraceniaceae (Pitcher-Plant Family) Gentianales: Apocynaceae (Dogbane/Milkweed Family) Gentianaceae (Gentian Family) Rubiaceae (Coffee Family) Lamiales: Lamiaceae (Mint Family) Oleaceae (Olive Family) Orobanchaceae (Broomrape Family) Scrophulariaceae (Snapdragon Family) Verbenaceae (Verbena Family) Solanales: Convolvulaceae (Morning Glory Family) Solanaceae (Potato/Nightshade Family)
Boraginaceae (Forget-Me-Not Family) Apiales: Apiaceae (Carrot Family) Asterales: Asteraceae (Sunflower Family) Campanulaceae (Bellflower Family) Dipsacales: Caprifoliaceae (Honeysuckle Family)
Identification characteristics: Nyssa, sometimes placed in a separate family (Nyssaceae), has alternate leaves, unisexual flowers with 5-8 petals, and variable numbers of stamens (~10). Cornus has 4 petals and stamens, the 4 sepal lobes often being minute. Some Cornus species have petaloid bracts surrounding a tight cluster of true flowers (see C. florida and C. canadensis). Most have opposite leaves (see C. alternifolia as an exception). Both Nyssa and Cornus produce drupaceous fruits from an inferior ovary, and both are woody trees or shrubs (C. canadensis appears herbaceous), and all Cornaceae have actinomorphic flowers. The leaves have arcuate veination, and when torn, strong vascular threads often remain attached as segments of leaf-blade are pulled apart. Interesting stuff: Many Cornus are valued ornamentals, although a fungal disease known as dogwood anthracnose is devastating populations in some areas. Nyssa is used as a timber tree and as an ornamental for its wine-red fall foliage. The drupes of both genera are very attractive to birds and other wildlife. Cornus alternifolia Pagoda Dogwood- This is the only dogwood in our area with alternate leaves, although they still have arcuate veination and strong vascular fibers. After flowering, the trees produce blue fruit. Pagoda Dogwood grows in rich soils as an understory or woodland-edge tree. Cornus canadensis, (closer) Bunchberry- This species looks like a miniature version of the Flowering Dogwood. It only grows in cold, acidic woods, usually near sphagnum in PA. The 'bunch' of berries (actually drupes) mature in a red cluster. Cornus florida (inflorescence), (branch), (population), (fruit), (flowers) Flowering Dogwood- Like Bunchberry, the clusters of small flowers are surrounded by four white (or occasionally pink) bracts in this most famous American dogwood. The bright bracts often hide the newly emerging leaves of the tree in spring. Large populations blooming in forest understories or edges are hard to miss, and this tree is one of the most popular horticultural trees in the world. When the bright red fruits mature into separate drupes, the individual flowers within the head become more apparent. Cornus serecia Red Osier Dogwood- This shrub is naturally found in swampy openings in PA, but is a commonly planted ornamental shrub as well. Whether this species is the same as Cornus stolonifera or whether the species should be split is still a matter of debate. Hydrangea arborescens Wild Hydrangea- Wild Hydrangea is usually found on moist, rocky slopes where large stands often form. Unlike the more famous horticultural Hydrangeas, this species often produces no large, showy, sterile flowers. Most Hydrangeas in the tropics are actually vines!
Impatiens capensis, (flower) Spotted Jewelweed- Jewelweeds are sometimes called Touch-Me-Nots due to their ripe seedpods, which explode when touched. In the same genus as garden Impations (a.k.a Sultanas), Jewelweeds are also annuals and must reseed themselves every year. Spotted Jewelweed's orange, somewhat tubular flowers are attractive to bees and hummingbirds alike, and are quite popular with the latter, which migrate when few other flowers are blooming in profusion. Impatiens pallida, (fruit) Pale Jewelweed- In addition to their pendulous, showy flowers, Jewelweeds also produce inconpicuous cleistogamous flowers. The crushed, succulent stems are rumored to be helpful for treating Poison Ivy, which is often found in close proximity! The tube and spur of jewelweed flowers is formed by the rear sepal. The other two sepals are inconspicuous and fall away early. Identification characteristics: Characters common to all Ericaceae are few, but a number of features are commonly found in many members of the family. Many, but certainly not all, Ericaceae are evergreen shrubs, many have urceolate corollas, and many release pollen from their anthers through pores rather than longitudinal slits. Sepals and petals are usually 5, but sometimes 4. Stamens are usually twice as many as the petals, although occasionally the same number. Ovaries may be inferior or superior. The petals are usually fused to some degree. Most have actinomorphic flowers, but some (see Rhododendron spp.) are slightly zygomorphic. Fruits are often capsules or berries. Interesting stuff: Ericaceae all have close association with ascomycete mycorrhizal fungi, which help them to uptake nutrients in acidic environments where they are usually unavailable to plant roots. For this reason, Ericaceae often dominate environments with acidic soils, such as sandy barrens and sphagnum bogs. Although it is believed that this fungal/plant relationship is usually mutualistic with the fungus receiving photosynthetically produced carbohydrates from the plant, some Ericaceae have exploited the symbiosis, becoming totally nonphotosynthetic and gaining all of their nutrition parasitically through fungi (see Monotropa). These plants are often indirectly parasitic on photosynthetic plants whose roots have mycorrhizae, the fungus serving as a carbon conduit from the autotrophic plant to the heterotrophic plant. Because of their lack of chlorophyll, these mycotrophs have been given familial recognition as Monotropaceae in the past, although both molecular and morphological data support their placement as a lineage derived from Ericaceae. Likewise, their closest relatives, herbaceous plants formerly placed in the family Pyrolaceae, are also now included as Ericaceae. There is reason to believe many members of this group have increased dependence on fungi and decreased need to photosynthesize on their own, as a species within the genus Pyrola has also independently become nonphotosynthetic. Note: Ericaceae, Pyrolaceae, and Monotropaceae are listed as separate families in your manual! Ericaceae contains many valuable ornamentals and edibles. Rhododendrons and Azaleas (genus Rhododendron), Heaths (Erica), and Mountain Laurel (Kalmia) are just a handful of the numerous ornamentals. Blueberries and Cranberries (Vaccinium) are also Ericaceous. Chamaedaphne calyculata Leatherleaf- This shrub soon becomes a dominant species in sphagnum bogs. Notice the urn-shaped corollas, typical of many Ericaceae. Although the habit and flowers of this species resemble a blueberry, the ovaries are superior rather than infoerior and form a dry capsule rather than a berry. Epigaea repens, (white flowers), (pink flowers) Trailing Arbutus- The sweet-scented blooms of Trailing Arbutus are often hidden beneath the leathery leaves. This plant is invariably found in sandy, acidic soils. It is one of the earliest blooming wildflowers in some areas, and is commonly visited by the first emerging bumblebees of spring. Gaultheria procumbens Wintergreen- The berries of Wintergreen, also known as Teaberry, have a wintergreen flavor; the leaves have a similar scent. Although they may cause stomach upset in very large quantities, they are a welcome sight in the woods during a long hike. Sometimes the berries remain on the plant throughout winter into the following spring. The plants are sometimes used horticulturally as a groundcover for acidic, shady locations. Gaylusacia baccata Black Huckleberry- This species can be found in dry, rocky areas as well as the margin of sphagnum bogs. The leaves are dotted with glands on both the upper and lower surface, which helps distinguish them from blueberries, the lowbush varieties of which are often called Huckleberries. Black Huckleberry makes black fruits, but lowbush blueberry fruits are also often black. Kalmia latifolia, (closer) Mountain Laurel- The state flower of PA, this shrub is common in rocky woods. The flowers seem to get more pink in sunny locations, but I might just be imagining things. Sometimes they form dense, beautiful stands in rocky powerline cuts where other woody vegetation is kept from growing high. The filaments are bowed outwards under tension, and the anthers are tucked into small pouches on the corolla. When a prospective pollinator contacts the flower, the anthers spring out and tag the pollinator with pollen. Rhododendron maximum (white), (purple) Rhododendron- This species is also known as Bay Laurel. Notice the blotch of spots on the upper corolla lobe, an indicator that the flowers are slightly zygomorphic. White is the predominant color of this wild Rhododendron species, but many individuals have a slightly pink to purple tinge to them. Rhododendron periclymenoides Pinkster Flower Azalea- This beautiful shrub is lanky by itself, but often forms small colonies from the roots. The flowers bloom before the leaves are expanded. Large Swallowtail Butterflies (genus Papilio) often visit the flowers of our native Azaleas and are probably an important pollinator. The flowers of this species have a faint scent, if any at all. Rhododendron prinophyllum Rosebud Azalea- Very similar to Pinkster Flower, this species is more glandular, less colonial, and has very fragrant flowers. Where the two co-occur, it often seems to flower slightly later. Azaleas tend to grow in sandy or rocky, acidic soils and don't transplant well when their micorrhizae are disturbed. Vaccinium angustifolium Lowbush Blueberry- These small blueberries are common in rocky, acidic woods. They often form extensive thickets. A few other 'lowbush' species occur in our area. Characters used for identifying the species include leaf veination, marginal teeth, stem color, and berry flavor. Vaccinium corymbosum, (fruits), (fruit closer) Highbush Blueberry- This species is most common around sphagnum bogs, where it may cover vast areas. Most cultivated blueberries originally stem from this species, at least as one parent. Once ripe, the fruits don't persist on the plant for very long, either being eaten by wildlife or falling to the ground to rot. In early autumn, a large stand of highbush blueberry can be quite stunning, as the leaves turn a brilliant red color. Vaccinium macrocarpon Cranberry- Cranberries like to grow in moist, very acidic habitats and are often even abundant along streams polluted by acid runoff from stripmines. Vaccinium stamineum Deerberry- Unlike the previous two Vacciniums, this species doesn't usually have tasty fruits. The corollas are open in the bud, and don't appear urceolate like other blueberries. The vegetation of this shrub is not very palatable to deer, so the shrub may form quite dense stands in the understory where overbrowsing occurs (i.e. most of PA). Monotropa hypopithys (yellow), (closer), (flowers), (4), (5), (6), (7), (red), (2) Pinesap- This species seems to be more restricted to growing underneath evergreens than Indian Pipe. Unlike Indian Pipe, Pinesap has more than one flower per stalk. A definite dimorphism occurs in stem/flower color in this species. The red population shown in the photograph was found less than a mile from the yellows, but bloomed a month later. Monotropa uniflora, (pollination) Indian Pipe- Indian Pipes are common in acidic woods dominated by oaks, pines, hemlocks, etc. Although nonphotosynthetic, it's still a flowering plant, as the Silver-Spotted Skipper in the photo can attest. The ghostly white pipes develope from mid-June to July. As the seed capsule matures, the flower turns upright. The old fruit stalks are tough and may be found standing a year or more after originally formed. Each contains many dustlike seeds that are easily blown for great distances on the wind. Chimaphila maculata, (closeup) Spotted Wintergreen- The leaves are striped, not spotted, in this attractive denizen of acidic woods. Like many Ericaceae, Chimaphila releases its pollen through pores at the anther tips. Although it appears herbaceous, technically Chimaphila is a dwarf, evergreen shrub. Pyrola elliptica Shinleaf- This species is usually found in acid soils under oaks and pines. It often forms colonies through creeping rhizomes. A species of Pyrola exists that is totlly nonphotosynthetic, indicating just how dependent these plants are on their micorrhizal fungi and how close they are to a Monotropa-like switch to complete dependence on a host. Fouquieria splendens Ocotillo- (photo from SW Texas)- A familiar plant of the desert Southwest and NW Mexico, Ocotillo looks like a wirey cactus. After a rain, however, it will briefly produce small leaves for photosynthesis. The red flowers, which are tubular with fused petals, are an important food source for hummingbirds in the desert. *Polemoniaceae: (Phlox Family) Identification characteristics: Like most members of Lamiales, Solanales, and Gentianales, Polemoniaceae have 5 fused sepals, 5 fused petals, and 5 stamens adnate to the corolla. However, unlike these groups Polemoniaceae has three carpels which are usually visible as three style or stgma branches. The superior ovary eventually forms a capsule as the fruit. The flowers are always radially symmetric. The leaves may be opposite (see Phlox) or alternate (see Polemonium) and simple (Phlox) or compound (Polemonium). Although our North American representatives are herbaceous, some members of this family may be woody and/or viney. Interesting stuff: Phlox, Polemonium, and other genera are commonly cultivated and hybridized for ornamental use. The family was once thought to more closely related to Solanales, Boraginaceae, or Lamiales, but molecular evidence now firmly places it within Ericales. Phlox divaricata, (white morph) Wild Blue Phlox- Often cultivated as a garden ornamental, different individuals of Blue Phlox show varying degrees of petal width and notching. White or nearly white variants aren't uncommonly found in a population. Reclining stems may root, leading to a nice clump-forming habit. Phlox glaberrima Smooth Phlox- This Phlox is native south of Pennsylvania, where it frequently forms hybrid swarms with other Phlox species. The petals of this and other Phlox species are convoluted, or corkscrew-twisted, in unopened buds. Phlox paniculata Tall Phlox- This species is the parent or one of the parents of most garden phlox varieties. Although the 'wild-type' form is common in gardens, it can also be found throughout much of Pennsylvania in alluvial soils, such as open floodplains along streams and rivers. Bumblebees, various butterflies, sphingid-moths, and hummingbirds are all attracted to the scented, tubular flowers of this species. In late summer, the leaves usually become infested with Powdery Mildew, which seems to have no lasting effect on the success of the plant the following year. Phlox subulata Moss Phlox- More commonly encountered in cultivation than in the wild, this creeping species is native to dry, sandy areas, rock outcrops, and serpentine barrens. In horticulture, it is sometimes referred to as 'Creeping Phlox,' a name more properly used for another species native to PA, Phlox stolonifera. Polemonium reptans, (closeup) Creeping Jacob's Ladder- This genus has pinnately compound, alternate leaves unlike Phlox. Although not truly creeping, the stems of this species recline more than others in the genus. It is sometimes referred to as 'Greek Valerian,' despite the fact tat it is native to the Eastern U.S. (not Greece!). It prefers alluvial, floodplains and moist, calcareous slopes. Lysimachia ciliata Fringed Loosestrife- Although a pretty pale yellow, the nodding flowers of Fringed Loosestrife are often held beneath the leaves. This is a common species in damp, semi-shady areas that occasionally flood. Lysimachia quadrifolia Whorled Loosestrife- These Loosestrifes are unrelated to the agressive, introduced Purple Loosestrife. Whorled Loosestrife is found in a variety of habitats, from woods to clearings, often, but not always, in sandy or acidic soils. Trientalis borealis Starflower- The whorled leaves and pointed petals both give this plant a star-like appearance. It typcally grows in cool, acidic woods, often near the perimeters of bogs. The number of petals is variable, usually from six to eight, in this species. *Sarraceniaceae: (Pitcher-Plant Family) Identification characteristics: This is the only North American plant family with leaves modified into insect-trapping pitchers. The flowers of this family are almost as distinctive as the pitcher shaped leaves. The style of the actinomorphic nodding flowers is highly elaborated in Sarracenia into an umbrella-shaped structure, which has pollen-receptive stigmatic surfaces beneath each of its 5 lobes. Members of the family have 5 separate sepals, 5 separate petals, and numerous stamens. Interesting Stuff: Sarraceniaceae were once grouped with other lineages of carnivorous plants despite the radically different floral and trap morphology of the different families. The unique flowers of Sarraceniaceae proved to be too aberrant for determining the closest relatives of the family, but molecular data clearly supports placement within Ericales. The center of diversity for the genus Sarracenia is the coastal plain of the southeastern U.S., but Sarracenia purpurea (see below) can be found in bogs across much of Canada and the northern U.S. Two other unrelated carnivorous plant lineages show striking similarity in pitcher morphology to Sarraceniaceae: the Australian Cephalotaceae (a Rosid) and the southeast Asian Nepenthaceae (a Caryophillid). Sarracenia purpurea, (pitcher closeup) Purple Pitcher Plant- In PA this carnivorous plant digests insects in sphagnum bogs where nitrogen is at a premium. Near the top of the inner pitcher are numerous small, downward-pointing hairs that make it easy for insects to slide downwards into the pitcher, but difficult for them to crawl upwards towards escape. Pitcher plants can also be found in the extremely alkaline habitats of marly fens, where mineral concentrations are high enough to reduce nutrient availability to levels similar to those found in acidic peat bogs.
*Apocynaceae: (Dogbane/ Milkweed Family) Identification characteristics: The family Apocynaceae, as formerly circumscribed, have actinomorphic flowers with 5 fused sepals, 5 fused petals, and 5 stamens that are fused to the petals and fused to each other via their anthers. The two carpels are variously fused and are often seemingly glued to the anther ring. The Asclepioid clade, formerly recognized as their own family (Asclepiadaceae) are now clearly accepted as being derived from within Apocynaceae. They have a unique flower morphology, with the androecium and gynoecium being fused into a structure known as the gynostegium, which is unrecognizable as either. The gynostegium contains 5 sets of pollinia (waxy masses of pollen) each of which is removed via attachment to a pollinators leg or other appendage (see movie for pollina location and removal). Each set resembles saddlebags, containing two pollinia (originating from the locules of two neighboring anthers) that are joined by an arm known as the translocator. Asclepioids have appendages that form a structure known as the corona between the gynostegium and petals. The corona often aids in guiding insect legs in the proper orientation with the gynostegium to receive and transfer pollinia. In Asclepias, each of the 5 segments is comprised of structures known as the horn and hood. Apocynaceae have opposite leaves, exude milky latex when damaged, and many (including the Asclepioids) have plumed seeds. The fruits are follicles. Interesting stuff: Many Apocynaceae produce very toxic chemicals that, along with their latex, discourage herbivory by animals from insects to large mammals. Asclepioids serve as the sole hosts for the Monarch Butterfly (see Other Organisms link) and relatives. Monarchs can sequester cardiac glycosides from milkweeds that produce them, thus making themselves distastful to birds and other predators. Many Apocynaceae are used horticulturally, and the nectar-rich flowers of the genus Asclepias are often particularly attractive to butterflies. Note: Asclepiadaceae and Apocynaceae are separate families in your manual! Apocynum cannabinum, (old follicles) Indian Hemp- This species has follicles containing tufted seeds and exudes milky sap like milkweeds. The name Indian Hemp comes from the tough fibers found in the stem of this species, which were used much like old-world hemp (Cannabis sativa) for making rope and other textile goods. The folicles of Indian hemp are long and very thin (spindle-shaped). Asclepias amplexicaulis, (top view) Blunt-Leaved Milkweed- This species is more common in prairie regions, but may be found in dry, sandy barrens in PA. The leaves have shorter petioles and blunter apices than Asclepias syriaca, and they usually also have a wavy (crispate) margin. Asclepias asperula, (inflorescence) Antelope-Horn Milkweed- (photo from central TX) This species grows in dry areas from TX to the rockies. It can be found in heavy mineral, serpentine soils where few other plants can grow. Asclepias exaltata Poke Milkweed- Like other milkweeds, this species has a corona above the reflexed petals (corona is white, petals are green). Poke Milkweed is vegetatively quite similar to Common Milkweed, but usually has more tapered leaves at the base and apex, and smooth, not warty, follicles. Asclepias incarnata (patch), (inflorescence), (pollination) Swamp Milkweed - This species has one of the most pleasant fragrances of any native flower. The legs of these bumblebees were covered with saddlebag-like bundles of pollen (pollinia). Wasps and butterlies also can commonly be seen visiting this species which, as its name suggests, usually grows in wet areas. Asclepias quadrifolia, (umbel) Four-Leaved Milkweed- This species blooms earlier than most other milkweeds; it produces long, spindle-like seedpods. The umbels have fewer flowers than most other species of Milkweed. Four-Leaved Milkweed is usually found growing on wooded slopes. Asclepias syriaca, (inflorescence), (fruit), (dehiscing fruit) (2) Common Milkweed- This common roadside and field species is a favorite host of Monarch Butterfly caterpillars in our area. The rhizomes can creep for meters under the soil surface, often resulting in large clonal patches. Milkweed patches often have their own diverse insect fauna; in addition to Monarch Butterflies, Milkweed Beetles, Milkweed Bugs, Assasin Bugs, Milkweed Tussock Moths, and Yellow Aphids can usually be found, to name a few. Asclepias tuberosa, (inflorescence), (bumblebee carrying pollinia on legs), (flowers) Butterfly Weed- The tough taproot of Butterfly Weed can thrive in dry soils of roadsides, railroad beds, and dry grassland remnants. Butterfly Weed is aptly named, as it is a favorite of butterflies in early summer. Occasionally, the plants will have a second flowering in late summer. Asclepias verticillata Whorled Milkweed- Whorled Milkweed usually grows in dry, rocky slopes in Pennsylvania. It can be found in limestone prairie remnants and serpentine barrens alike. The leaves are unusually thin for Asclepias. Asclepias viridiflora Green Milkweed- Although the flowers of Green Milkweed aren't colorful, the stout habit and petals tightly appressed to the stem make it attractive. Like Whorled Milkweed, this species is often found in open, xeric habitats such as limestone prairies and serpentine barrens. *Gentianaceae: (Gentian Family) Identification characteristics: Gentianaceae are herbaceous, have opposite leaves, actinomorphic flowers with usually 5 fused sepals and 5 fused petals (sometimes 4, see Gentianopsis and Obolaria), with an equal number of stamens attached to the corolla. The two carpels are fused into a superior ovary, and the stigma is usually 2-lobed. Interesting stuff: Species of Gentian produce the bluest of blue flowers in PA late in the season. Members of the family are highly dependent on mycorrhizal fungi, and some have become completely non-photosynthetic mycotrophs (see Monotropa in Ericaceae above as a parallel evolutionary event). Within Pennsylvania, representatives of a range of mycotrophy occur; the Gentians (Gentianella, Gentiana, and Gentianopsis) appear photosynthetically normal, Obolaria has reduced, purplish leaves, and Bartonia is effectively leafless. Bartonia virginica Yellow Bartonia- Bartonia has minute scales for leaves, gaining practically all of its nutrition from fungal association rather than through photosynthesis. A common name for some members of the genus is Screwstem, as sometimes ridges in the stem indicative of a rotation during growth are apparent. Bartonia is typically found in the nutrient-poor soils of bogs and peat barrens. Gentiana clausa, (2), (3), (4) Bottle Gentian- Bumblebees and Carpenter Bees must force their way into the closed corollas of this species. However, because few other insects are strong enough to enter, there is usually plenty of nectar to reward them for their hard work. Like many species of Gentian, these plants have webbing, or pleats, between the corolla lobes. Gentianella quinquefolia Stiff Gentian- This Gentian is often found in moist, open areas at higher elevations, but is occasionally found in dry sites as well. Although usually more diminutive, it tends to produce more flowers per plant than other Gentians. Gentianopsis crinita (Gentiana crinita), (2), (flower), (3), (4) Fringed Gentian- Gentians possess the deepest blue flowers of all plants in PA. Fringed Gentian is an uncommon biennial, but is one of the most beautiful native plants. The flowers only open in the sun and close every evening until pollinated. Light is required for the seeds to germinate, and a diminutive rosette of leaves is produced the first year. Thus, the plants only persist in locations where open ground is available and there is little competition for space. Obolaria virginica, (purple) Pennywort- This mycotrophic relative of Gentians is rare in PA. It only has 2 sepals and 4 petals. Although normally white, the flowers of Obolaria occasionally are purplish. The purplish bracts conduct most of the photosynthesis in this plant. Spigelia marilandica Indian Pink- (native to S.E. United States) Indian Pink contains very toxic alkaloids that deter herbivory. Identification characteristics: In our range, Rubiaceae have 4 fused sepals, 4 fused petals, and 4 stamens attached to the corolla (flower parts sometimes 5s in the tropics). The ovary is inferior, and is comprised of 2 carpels (occasionally 4). Leaves are opposite, sometimes appearing whorled. Fruits are highly variable. Interesting stuff: A large proportion of Rubiaceae demonstrate a feature known as heterostyly, where multiple floral morphologies are present in populations, each of which can only be successfully pollinated by a flower with different morphology. In Rubiaceae, distyly is prevalent, where some flowers of a given species have long, exerted stamens and short, included styles. These can only produce seed from pollen that is transferred from a flower of a morph with exerted style and stigmas and included stamens. Rubiaceae includes some ornamentals, but by far the most economically important product of the family is coffee. Quinine and ipecac are medicinal drugs that are extracted from members of Rubiaceae. Cephalanthus occidentalis Buttonbush- The vast majority of Rubiaceae are tropical shrubs, but this is the only woody member of the family native to the northern U.S. Hedyotis caerulea (Houstonia caerulea), (flowers) Bluets- Also known as Quaker Ladies, the wirey stems seem to barely be able to support the oversized flowers. The flowers are usually pollinated by small beeflies. Hedyotis longifolia Long-Leaved Bluets- This small-flowered species grows in dry, barren soils. Mitchella repens (Long-Stamen Form), (Long-Style Form) Partridgeberry- Like many Rubiaceae, Partridgeberry is heterostlyous, with two different flower forms. An individual with a long style can only be pollinated by a different individual that has long stamens. The flowers are paired at the end of the shoot, and the maturing gynoecia fuse to form a common berry between the flowers.
Ruellia humilis Wild Petunia- Wild Petunia grows on limestone substrates mostly south of MD, but can be found in extreme southern PA on limestone prairie remnants. Garden Petunias are in the family Solanaceae. Campsis radicans Trumpet Creeper- This species becomes much more common further south, where hummingbirds can often be seen visiting its large trumpets. It can be quite aggressive, spreading from seed and underground root sprouts and growing to tall heights. Catalpa speciosa Hardy Catalpa- This species is native to the lower Mississippi River valley but is planted and escaped throughout Eastern N. America. The fruit is a long, bean-like capsule. Buddleja davidii Butterfly Bush (non-native)- Cultivated forms of this shrub come in many different colors. As its name suggests, its flowers are very attractive to butterflies. Buddleja nitida (photo from Costa Rica)- Buddlejas are most common at high elevations in the tropics where temperatures stay cool and moisture is constant. Identification characteristics: Mints are one of the most distinctive of all plant families, with Verbenaceae (see below) as the only family where confusion might occur. Mints are generally very aromatic and have square stems and opposite leaves. The calyx is comprised of 5 fused sepals. The corolla is usually strongly bilabiate, often indistinguishable as originating from 5 petals. There are 4 stamens adnate to the corolla which are usually strongly didynamous, and the syle is usually forked at the end, indicating the 2 carpels. The ovary is 4-lobed and is a schizocarpic fruit, eventually splitting into 4 nutlets. The style is gynobasic (in traditional treatment of the family), penetrating between the lobes to the base of the ovary. The inflorescences of the family are often verticels, with clusters of flowers forming tiers in the upper leaf axils (see Lamium maculatum). Interesting stuff: Labiatae, the former name for this family, is still widely accepted and used. Lamiaceae are used for their oils, in teas, and as herbs and spices (oregano, sage, basil, etc.). Many species are also commonly cultivated as ornamentals for foliage, flowers, and fragrance. Our species are herbaceous, but in some regions Lamiaceae can be shrubs or even trees. Collinsonia canadensis, (closeup) Horse Balm- Horse Balm is usually found in rich woods with adequate moisture. The plants are less scented than many other mints. At first glance, the inflorescence of this species looks weedy, but the flowers are pretty and intricate when viewed individually. Lamium maculatum Spotted Dead-Nettle- Non-native. Like other members of the Mint Family, it has square stems, opposite leaves, verticillate inflorescences, and is aromatic. Monarda clinopodia Basil Balm- This Monarda is usually found in woods and edges. Hybrids with M. fistulosa are common along edges where both species occur. Monarda didyma, (inflorescence) Bee Balm- Commonly cultivated, many color varieties of Bee Balm now exist, but the wild scarlet type is most attractive to hummingbirds. Another name for Bee Balm is Oswego Tea. The Oswego tribe in New York were one of many tribes of Native Americans to use the leaves of this species to make a soothing beverage. Monarda fistulosa, (closer) Wild Bergamot- This Monarda is tolerant of dry soils and is usually found in open areas. Like Bee Balm, the leaves of Wild Bergamot are sometimes used to make tea. Bees are attracted to the minty flowers. Pycnanthemum muticum Hoary Mountain Mint- The leaves of this Mountain Mint are coated with whitish, velvety hair. The leaves are tasty when chewed, or can be made into a tasty tea. Scutellaria galericulata Common Skullcap- Common Skullcap can frequently be found near bogs and marshes. Unlike the following two species, only one flower is produced per axil. Scutellaria incana Downy Skullcap- This species has large, attractive flowers for the genus. It growns in drier habitats than Mad-Dog Skullcap. Scutellaria lateriflora Mad-Dog Skullcap- Flowers in the genus Scutellaria possess a projection on the top of their calyx, to which they owe their name. Utricularia vulgaris Common Bladderwort- The submerged leaves of this carnivorous genus contain traps that create a vacuum and suck up nearby microinvertebrates. Some bladderworts are rooted in the mud, whereas others are free-floating in the water. Identification characteristics: Most Oleaceae in our region are readily recognizable. They are mostly shrubs (some trees) with opposite leaves and no stipules. The leaves are usually simple, but are pinnately compound in Fraxinus (Ash trees). The flowers have 4 fused sepals, 4 fused petals, 2 epipetalous stamens, and a superior ovary formed from 2 carpels (usually evident as 2 stigmatic lobes). Fraxinus has reduced, wind-pollinated flowers that are unisexual (the plants being dioecious) with the perianth lacking or greatly reduced. Many produce drupes as fruits, but capsules are also not uncommon, and female Fraxinus flowers form winged samaras for wind dispersal. Interesting stuff: Oleaceae are most likely the first-brancing lineage of Lamiales. The wood of Ash trees is durable and is often used for axe and other tool handles and also for baseball bats. Olives and olive oil are important culinary products. Many Oleaceae are also popular ornamentals, including Lilacs, Forsythias, Privets, and Jasmine. Chionanthus virginicus Fringe Tree- This pretty dioecious small tree is rare in its natural woodland understory habitat in PA, but is commonly cultivated. *Orobanchaceae: (Broomrape Family) Identification characteristics: Identification of this family as traditionally circumscribed is very straight-forward, as it includes only plants with reduced leaves and no apparent chlorophyll. The flowers of the group are obviously of Lamialean origin, with 5 fused sepals, zygomorphic, bilabiate flowers that have fewer stamens (4) than corolla lobes (5), and superior ovaries formed from two carpels. The leaves are usually scale-like. Interesting stuff: These plants are nonphotosynthetic and are completely dependent upon an autotrophic host which they attach to the roots of via a modified root organ known as a haustorium. These parasites are undoubtedly derived from the same lineage as photosynthetic root parasites included in the traditional Scrophulariaceae (see discussion under Scrophulariaceae below). Conopholis americana (clump), (individual closeup) Squawroot- Squawroot is only found growing on the roots of Red Oaks or closely related trees. The yellow flowers produce thousands of seeds in each capsule of the pinecone-like plant. Squawroot is thought to be perennial, arising each year from the tumor-like interface between the host root and parasite. Conopholis mexicana, (patch) Mexican Squawroot (photo from SW TX)- Found only at high elevations in the Chisos Mountains in the U.S., Mexican Squawroot is more robust than its northern cousin, but similarly parasitizes Red Oak relatives. Epifagus virginiana (patch), (2), (closer), (flower) Beechdrops- This annual nonphotosynthetic plant is specific to American Beech (Fagus grandifolia) as its host. The lowermost flowers are cleistogamous, meaning they pollinate and set seed without ever opening. Although small, the flower structure of Epifagus is similar to Lamialean relatives. Orobanche uniflora, (flower) One-Flowered Cancer Root- The short stem of this parasite is mostly underground, with only the pedicel and flower being above-ground. This species usually grows in moist woods and can be found attached to the roots of many different hosts. Other Orobanche species introduced from the old world can become serious crop pests in the United States. *Scrophulariaceae: (Snapdragon Family) Identification characteristics: It is extremely difficult to find characteristics that apply across all Scrophulariaceae as traditionally recognized. Members of this family are probably better represented when split into separate families (see discussion below). In general, Scrophulariaceae is the dumping ground for taxa that don't fit in anywhere else in the Lamiales. They have round stems (unlike Verbenaceae and Lamiaceae), zygomorphic flowers, and form capsules as their fruits. There are usually 5 sepals (sometimes 4), 5 corolla lobes (also sometimes 4), usually 4 didynamous stamens (sometimes only 2), and the superior ovary is formed from 2 carpels. Leaves are most often alternately arranged, but opposite leaves aren't uncommon in the group. The zygomorphy of the corolla is sometimes very slight (see Veronica) but often very elaborate (see Mimulus). Interesting stuff: With the recognition of many well-accepted families, Scrophulariaceae, as traditionally circumscribed, is polyphyletic. Families such as Lamiaceae, Verbenaceae, Bignoniaceae, Acanthaceae, Orobanchaceae, Buddlejaceae and others are actually derived from within the "family." For this reason, Scrophulariaceae is currently being split between a number of families. Orobanchaceae now includes all root parasitic plants that were formerly included in Scrophulariaceae because they are still photosynthetic. Molecular evidence supports a single origin of parasitism within the "Scrophulariaceae" followed by multiple independent losses of photosynthesis (i.e. transition to an "Orobanchaceae" lifestyle). Many other Scrophulariaceae, including the genus Antirrhinum (Snapdragons), have been transferred to a family (tentatively called Veronicaceae) that includes wind-pollinated lawn weeds with inconspicuous flowers (formerly called Plantaginaceae). Most keys and herbaria still follow a traditional definition of Scrophulariaceae, as we will in this class for simplicity, because characteristics defining these new groupings are microscopic or otherwise not readily visible (such as underground root parasitism). Scrophulariaceae contains many popular ornamentals including Snapdragon (Antirrhinum), Foxglove (Digitalis), and Penstemon. Agalinis purpurea Smooth Gerardia- Although green-leaved, the roots of this pretty-flowered species attach to and parasitize the roots of many host plants. Agalinis tenuifolia Slender Gerardia- This species can be grown for a while in the absence of a host, but does much better when attached to another plant. Aureolaria laevigata, (closer) Appalachian False Foxglove- This parasitic genus and Agalinis were formerly lumped together in the genus Gerardia. Castilleja coccinea, (inflorescence) Indian Paintbrush- There are many species of Castilleja in the western U.S., but this is the only species in PA. They are all root parasites. The flowers are greenish and inconspicuous, but the bright bracteal leaves help attract hummingbirds. Castilleja purpurea Purple Indian Paintbrush (photographed in SW Texas)- Despite the species name purpurea, the bracts of this plant may vary from yellow to orange to red to purple in a single population. Castilleja talamancensis Talamancan Paintbrush (photo from Costa Rica)- Species diversity of most plant groups increases in the tropics, but Castilleja is a genus that is most species-rich in the Western U.S. and Mexico. Only a couple species make it as far south as Costa Rica, and they are only found near the highest elevations in the mountains. Calceolaria sp.- Species in this genus produce oil, not nectar, from their flowers. Pollination is limited to a species of oil-collecting bees. In recent circumscriptions of Lamiales, this genus is usually put in its own family, Calceolariaceae. Chelone glabra White Turtlehead- The leaves of Turtleheads are often decimated by the feeding of Baltimore butterfly caterpillars. The plant grows in wet ground of floodplains and marshes. Melampyrum lineare Cow-Wheat- This annual plant partially relies on connecting to the root of a host plant to supplement its nutrition gained from photosynthesis, Mimulus ringens, (flower) Monkeyflower- This species grows in wet areas. It appears to be more closely related to the parasitic lineage of Lamiales than to true 'Scrophs'. Can you see a monkey face in the flower? Penstemon digitalis Tall White Beardtongue- This genus has many more representatives in W. N. America, but this attractive species is found in PA. Penstemon hirutus, (2) Northeastern Beardtongue- This species grows on rocky slopes in limestone-derived soils in PA. As its species name implies, the plants have hirsute hairs on the corolla and elsewhere. Scrophularia marilandica (habit), (flower) Eastern Figwort- The square stems with opposite leaves on this specis often earn it the colloquial name "carpenter's square". This genus is the only one native to E. North America that is retained in Scrophulariaceae in new taxonomic treatments. Veronica persica Birdseye Speedwell- Nonnative. Veronicas are common lawn and garden weeds. Note the slightly zygomorphic flower, only 4 petals, and two stamens. Veronicastrum virginianum Culver's Root- Veronicastrum is more common further west in moist prairies, but in PA it can often be found in moist, open limestone woods. *Verbenaceae: (Verbena Family) Identification characteristics: Verbenaceae is closely allied to Lamiaceae, as is evidenced by their square stems, opposite leaves, and zygomorphic flowers with didynamous stamens and a 4-lobed ovary that usually forms a schizocarp of 4 nutlets. Verbenaceae, as traditionally defined, have a terminal style that doesn't penetrate between the 4 ovary lobes. The inflorescence is generally terminal and indeterminant, unlike most Lamiaceae. Interesting stuff: Separation of Verbenaceae from Lamiaceae based on style morphology has proven to be inappropriate based on molecular phylogenies. Molecular systematists have transferred over two-thirds of traditionl Verbenaceae genera to Lamiaceae in order to make the mints a monophyletic family. The placement of Phryma (see below) within the genus is also debated. Many Verbenaceae, both as traditionally and phylogenetically recognized, are cultivated as ornamentals. Phryma leptostachya Lopseed- Unlike most other Verbenaceae, Phryma produces an achene rather than nutlets. It is sometimes placed in its own family. Verbena hastata Blue Vervain- This attractive plant is common in wet fields and edges. The square stem and opposite leaves help show affinities to Lamiaceae. Like most other Verbenaceae, the inflorescence is a bracteate, indeterminate spike.
*Convolvulaceae: (Morning Glory Family) Identification characteristics: Morning Glories are almost always viney to some degree. They have alternate, simple leaves that are commonly cordate to sagittate at the base. The flowers have 5 fused sepals, 5 petals that are often fused the entire length of the actinomorphic corolla (See Argyreia, Calystegia, and Ipomoea below). The 5 stamens are adnate to the corolla and there are two carpels fused into a superior ovary. Each carpel produces 2 ovules, which results in a maximum of 4 seeds per capsule. The petals are twisted (convoluted) in the bud (look at "corkscrew" flower buds in the lower left of Ipomoea purpurea picture below). Interesting stuff: The genus Cuscuta (my specialty) is often considered to be its own family (Cuscutaceae) based on its parasitic lifestyle and accompanying morphological eccentricities. However, it is clearly related to Convolvulaceae and most experts include it in this family. The plants often produce potent alkaloids, which may be concentrated in their seeds. Some of these compounds may be extracted as hallucinagens, others are highly toxic. Many species of various genera are among the most popular ornamental vines. Calystegia sepium and Convolvulus arvensis are sometimes garden and agricultural weeds, and species of Cuscuta cause serious agricultural damage to some crops through their parasitism. Argyreia nervosa Wooly Morning Glory- Non-native. Wooly Morning Glory is sometimes cultivated in greenhouses and is often called "Wood Rose." Calystegia spithamaea Upright Bindweed- This species is unusual for Convolvulaceae in not being very viney. It grows in dry or rocky habitats in PA. A variety of this species specializes in growing in the inhospitable environment of Shale Barrens. Cuscuta campestris (habit), (flowers) Field Dodder- Field Dodder is native to N. America but has been spread as an agricultural weed around the world. It is particularly damaging to Alfalfa. Each flower forms a seed capsule that will contain 1 to 4 seeds. Cuscuta cephalanthi, (inflorescence), (maturing capsules) Buttonbush Dodder- Buttonbush Dodder usually grows in marshy areas or streambanks. The withered corolla tops the seed capsule. Cuscuta compacta, (flowers), (adventitious flower buds) Compact Dodder- Compact Dodder often grows in swampy areas on shrubs such as Alnus and Aralia on whose stems it coats with inflorescences. Each flower of Compact Dodder is subtended by multiple sepal-like bracts. Cuscuta gronovii (habit), (damage on Impatiens), (flowers), (fruits) Common Dodder- Common Dodder can parasitize a wide variety of hosts at once; this individual is choking ten dicot species at once. Common Dodder is the most widespread and common Cuscuta found across most of North America. Occasionally it becomes a pest on blueberry or cranberry farms. Ipomoea tricolor, (2) Blue Cultivar Morning Glory (non-native)- Many cultivars exist for this species, but all have funnelform corollas common in Convolvulaceae. *Solanaceae: (Potato/Nightshade Family) Identification characteristics: Solanaceae may be trees or shrubs but are herbs or vines in our range. The leaves are alternate. Flowers have 5 fused sepals, an actinomorphic corolla of 5 fused petals that are sometimes connate to the tip as in Convolvulaceae, 5 stamens adnate to the corolla, and 2 carpels fused into a superior ovary. The fruit may be a many-seeded capsule (usually>4 seeds, compare to Convolvulaceae) or berry. The corolla is often plicate (showing fold lines). Anthers may dehisce in typical, longitudinal slit-fashion, or through pores at the apex of the anther. Many have the 5 anthers ringed in a cone-like structure that release pollen from these pores when buzzed by the wings of a bee. Interesting stuff: Solanaceae produce some of the most toxic natural chemicals known to man, but also produce many of the most agriculturally important crop plants (e.g.g. tomato, tomatillo, potato, eggplant, and peppers). Tobacco (Nicotiana tabacum) is an economically important species whose alkaloid content is exploited for human consumption. Seeds of Datura species are often eaten for their hallucinagenic qualities, but this practice often results in death. Many Solanaceae are cultivated as ornamentals, including species of Nicotiana and Petunia. Datura stramonium, (fruit) Jimsonweed, Thornapple (not native)- This weedy species was introduced early on to the first European settlements, including Jamestown. It is thought to be native originally to the New World tropics, but now is widespread (the flower photo was taken in Chile, the fruit in State College, PA). It is highly poisonous, although ingesting small quantities of seed may result in hallucination. However, this practice has led to the death of many humans, as the amount of toxins is unpredictable from plant to plant. Because of this, and because it is equally toxic to cattle, this species is listed as a noxious weed in PA. Solanum carolinense Horse Nettle- The flowers of Horse Nettle resemble those of its close relatives, Tomato and Pepper. The plant has numerous stout prickles on its stem. The fruit is a marble-sized, yellow berry. Solanum glaucophyllum (photo from Argentina)- Like other Solanums, the anthers form a cone in this species which is used to effect buzz pollination.
*Boraginaceae: (Forget-Me-Not Family) Identification characteristics: Boraginaceae have alternate, simple leaves (sometimes compound in Hydrophyllaceae) and they are often (but not always) hairy plants. The 5 sepals are usually obviously fused, and the 5 petals are fused into an actinomorphic corolla. The 5 stamens are adnate to the corolla. The superior ovary is formed from 2 carpels, and the fruit is usually a schizocarp that splits into 4 nutlets (the ovary forms a capsule in Hydrophyllaceae). The inflorescences of Boraginaceae are helicoid/scorpioid cymes, one sided inflorescences that uncoil and elongate as the flowers open towards the tip. Interesting stuff: Boraginaceae have been tentatively placed in Solanales, although they have also been hypothesized to have affinities to Lamiales. Hydrophyllaceae are usually separated, but probably are derived from within lineages considered as Boraginaceae. Parasitic plants put in the family Lennoaceae may also be derived Boraginaceous plants. The ovaries in some species not in our range sometimes form drupes. Our species are herbaceous, but they may be trees or shrubs elsewhere (occasionally even vines). Some are cultivated as ornamentals, such as Myosotis (Forget-Me-Not). Note: Hydrophyllaceae and Boraginaceae are separate families in your manual! Lithospermum canescens, (flowers) Hoary Puccoon- Hoary Puccon is uncommon in PA, but the bright orange flowers are hard to miss where it grows. Usually found in prairie-like habitats, it can be encountered in limestone glades and dry woods in PA. Mertensia virginica, (2), (white form) Virginia Bluebells- This species is often found in wooded floodplains. The flowers are pink in bud, turning blue as they open. Color variants of Virginia Bluebells, such as these "whitebells," are uncommonly encountered. Myosotis arvensis Forget-Me-Not (non-native)- The flowers of most Boraginaceae are borne in helicoid cymes, which seemingly uncoil as the inflorescence ages. Hydrophyllum virginianum (purple), (white) Virginia Waterleaf- This species is found in two color phases which are found side by side in its range. The helicoid cymes of Hydrophyllaceae help show their affinities to Boraginaceae. Phacelia bipinnatifida, (closeup) Purple Phacelia- (Native to Southeast U.S.)- Purple Phacelia grows in moderately moist soils rich in calcium. It is a biennial. The stamens have relatively long, spreading hairs on their filaments.
Ilex montana, (closer, male flowers) Mountain Holly- Like other members of the Holly family, this speciesis dioecious. It is found in the Northern part of the state and south in the mountains in rocky woods. Nemopanthus mucronatus (in fruit), (closeup of fruit) Mountain Holly- Like Ilex montana, this species grows in cooler areas such as bogs in the mountains. They also both have deciduous leaves unlike the more famous holly trees used for X-mas decoration. Nemopanthus can be separated from Ilex by its untoothed leaves and, when in flower, by its unfused petals with unattached stamens.
Identification characteristics: Apiaceae have an inferior ovary at the top of which the sepal lobes are minute or apparently absent. There are 5 petals, which are typically unfused, and 5 stamens. There are two carpels (up to 5 in Aralioids/Araliaceae) which are held a top the ovary on a platform known as a stylopodium. Leaves are alternate in all members, usually with a sheathing petiole base, and the inflorescences are characteristically umbels or compound umbels. The family is traditionally comprised of herbaceous species, but most Araliaceae are woody. The ovaries of most Apiaceae form a schizocarp that splits into two dry halves, but Aralioids produce berries. Interesting stuff: An alternative name for Apiaceae that is commonly encountered is Umbelliferae, which is descriptive of their inflorescence type. Apiaceae (and Araliaceae) were once placed in the Rosids based on morphology, as the separate petals are not characteristic of core Asterids. Many are useful as food (carrot and celery), herbs (parsley, cilantro), and medicinals (ginseng). However, many are highly toxic and commonly cause death in cattle when grazed. The Hemlock that poisoned Socrates belongs to this family. Many also contain furocoumarins, chemicals that render the skin extremely photo-sensitive, resulting in severe rash/sunburn if one gets sap on his or her skin. Some are also used as ornamentals, such as Hedera helix (English Ivy). Recognition of Araliaceae as a family is likely to make Apiaceae as tradionally recognized a polyphyletic group. Some authorities name basal lineages responsible for the paraphyly as their own families so that Apiaceae and Araliaceae can still both be monophyletically recognized. Note: Araliaceae and Apiaceae are separate families in your manual! Erigenia bulbosa Harbinger-of-Spring- This little woodland plant is one of the first things to flower in earliest spring. It can be found in western PA in moist forests. Eryngium horridum Rattlesnake Master (photo from Argentina)- The unpalatability of this plant to cattle is obvious in this picture. The umbels in this genus are constricted to an involucrate head reminiscent of Asteraceae. Rattlesnake Masters can be found on the N. American prairies as well as the grasslands of Argentina. Osmorhiza claytonii Sweet Cicely- The leaves of Osmorhiza somewhat resemble a fern when the plants aren't in bloom. The crushed leaves of this species don't have a strong odor. Osmorhiza longistylis Aniseroot- Although in outward appearance this species is almost identical to O. claytonii, when the leaves, stems, or roots are bruised or crushed, they give off a strong anise (black licorice) fragrance. Taenidia integerrima Yellow Pimpernel- Notice the compound umbel inflorescence; umbels (or compound umbels) are typical of Apiaceae. Zizia aptera Heart-Leaved Golden Alexanders- The lowermost leaves are "heart-leaved," while the upper leaves are ternately compound. Aralia hispida, (2) Bristly Sarsparilla- This species is small in stature but is actually a short, woody shrub. The hispid, or bristly hairs that are found on the stems may disappear with age. Aralia nudicaulis Wild Sarsparilla- The species name nudicaulis refers to the naked flowering stem. Aralia racemosa Spikenard- Spikenard grows in rich, humusy woods. The large, shrub-like plants die back to the ground each year. Aralia spinosa (infructecence) (2) (3) Devil's Walking Stick- The straight, unbranched, spiny stems of Devil's Walking Stick often grow in colonial thickets, Panax quinquefolius, (2) American Ginseng- Because it is prized for its medicinal roots, which may fetch a high price in Asian markets, American Ginseng has been overcollected and is now much more uncommon in PA than it once was, except in places where it is sutainably harvested and repanted by responsible 'ginsengers'. Plants may begin flowering when they only have two leaves (each usually with 5 leaflets). With age, the plants gain 3 leaves (prongs), and very old and/or healthy plants may produce 4 or more. Panax trifolius Dwarf Ginseng- This species is more common than the now rare, overcollected American Ginseng. The bulbous root has no economic value, however. As this picture shows, trifolius isn't always an appropriate species name in larger specimens.
*Asteraceae: (Sunflower Family) Identification characteristics: Most Asteraceae are readily recognized by their composite inflorescences, comprised of numerous flowers crowded into a dense head (known as a capitulum) surrounded by a collection of bracts (involucre). These clusters are sometimes secondarily aggregated. Individual Asteraceae flowers have fused petals, syngenesious anthers, an inferior ovary comprised of 2 carpels, and no apparent sepals. Two distinct flower types are found. Some flowers, called disk flowers, are tubular and actinomorphic. Other flowers, called ray flowers, may be ligulate, with all 5 fused petals shifting to one side forming a strap-shaped corolla that resembles one petal instead of a flower. Asteraceae capitulums may have all disk flowers (see Vernonia gigantea or Eupatorium rugosum), a ring of ray flowers surrounding a central "disk" of disk flowers (see Aster, Erigeron, Helianthus), or all of the flowers in a capitulum may be ligulate ray flowers (like Dandelion; see Krigia biflora and Tussilago farfara). Leaves may be opposite or alternate. In our range, Asteraceae are practically all herbaceous. They may have opposite or alternate leaves. The fruits of Asteraceae are achenes, often topped by a persistent pappus. The pappus is derived from sepals and often aids in seed dispersal. It may consist of scales, awns, or often capillary or plumose bristles. Each flower in a capitulum is often subtended by a scaly bract. A feature often used in keys for Asteraceae is whether these bracts are left on the inflorescence receptacle when the flowers or fruits are removed or whether the receptacle is smooth and bractless (naked receptacle). Interesting stuff: Asteraceae is generally circumscribed as the largest family of angiosperms with more than 1,200 genera and over 20,000 species. Most species promote outcrossing by a mechanism known as plunger pollination. The two style branches are held tightly together, concealing the stigmatic surfaces. The outer stylar surfaces often have patterns of hair which, when pushed through the tube formed by the fused anthers, pick up the pollen for presentation to prospective pollinators (see picture link above). The flower later becomes functionally female, as the style branches spread apart and expose the stigmatic surface. In many Asteraceae that have both ray and disc flowers, the inner disk flowers are fertile but the ray flowers are sterile and only serve for pollinator attraction. In others, the disc flowers are functionally male and the ray flowers functionally female. Asteraceae provide a large number of economically important species. Consumables include sunflower seed and oil, jerusalem artichoke, and lettuce. Some important organic insecticides (e.g. pyrithrins) are produced from extracts of Asteraceous plants. Various Asteraceae can be weeds, especially outside of their natural range (e.g.g. many Cirsium, Carduus, Centaurea). Members of the genus Ambrosia (ragweeds) have evolved to be wind pollinated. Their wind-born pollen is responsible for most fall allergies (hay fever). Another Asteraceae genus, Solidago (goldenrods), is often blamed for this phenomenon because its gaudy inflorescences are blooming at the same time as the inconspicuous flowers of ragweed. Asteraceae provide a large number of important ornamentals such as Ageratums, Dahlias, Cosmos, Zinnias, Black-Eyed Susans, Coneflowers, Coreopsis, Daisies, etc. Although there are various Asteraceae species in flower thoughout the season in PA, their flowers predominate the late-summer/fall landscape. Another widely accepted name for Asteraceae is Compositae. Ambrosia artemisifolia Common Ragweed- Although showy fall composites, such as Goldenrods and Asters, are often blamed for hay fever, the inconspicuous, wind-pollinated inflorescences of Ragweeds are responsible for most fall allergies. Aster cordifolius (color-change in disk flws) Heart-Leaved Blue Aster- This is a common aster of wooded slopes in PA. The blooms range from blue to practically white. Aster divaricatus White Wood Aster- Some inflorescences on this Aster have turned purple, indicating to pollinators that they no longer offer a reward. White Wood Aster is one of the most common flowers in late summer woods of central PA. Aster lanceolatus (involucre), (disk flower), (ray flower) Panicled Aster- The involucres of Asters consist of numerous, imbricate bracts. Each disk flower will produce one seed (achene). Notice the achene topped by a pappus of long bristles. Although they look like one petal, the rays are really ligulate flowers with 5 fused petals, complete with ovary, pappus, etc. Aster lateriflorus (closer) Calico Aster- Like some other species of Aster. Calico Aster exhibits a color change in the disk florets with age (cream changing to purple). Aster macrophyllus Bigleaf Aster- The large, basal leaves of this colonial woodland and edge species are conspicuous from spring until fall. Aster novae-angliae, (inflorescence) New England Aster- New England Aster is one of the latest wildflowers in our area, blooming alongside fall Goldenrods. Notice the purple ligulate ray flowers and the small, tubular, yellow disk flowers. Aster phlogifolius (2) Late Purple Aster- Late Purple Aster is closely related to Aster patens and is often listed as a variety of that species. Aster pilosus, (closer), (receptacle) Awl Aster- This widespread Aster is one of the most common plants of disturbed areas and old fields. Like most other Aster species, Aster pilosus blooms in late fall, continuing into November even through early frosts. Receptacles in the genus Aster are naked, meaning they are simply pitted disks lacking bracts subtending each flower. Aster prenanthoides Zigzag Aster- The stems of this species "zigzag" between the sessile, somewhat clasping leaves. Baccharis magellanicus (photo from Patagonian Andes, Argentina)- Although many species in this genus are shrubs that can attain reasonable heights, this species grows prostrate on the windswept ground of Patagonia. Bidens aristosa Tickseed Sunflower- Species of Bidens can be difficult to tell apart. Shape of the achene (seed) is an important character. Unlike this species, some species lack showy ray flowers. Cirsium discolor, (inflorescence closer), (with bee) Field Thistle- Many thistles, like Canada Thistles, Bull Thistle (Cirsium), and the Musk Thistles (genus Carduus) are exotic, invasive weeds of sunny habitats. Field Thistle, however, is a native species invariably found in dry to moist calcareous soils. It can be distinguished from other thistles in our area by it's unwinged stems, deeply-divided pinnate leaves, and white-tomentose undersides to the leaves. Cirsium undulatum Wavy Thistle (photo from Utah)- Wavy thistle is named for the undulating margins of its spiny leaves. Coreopsis lanceolata Lance-Leaved Coreopsis- A widely planted ornamental, this Coreopsis is also a parent of many garden hybrids. Coreopsis tripteris Tall Coreopsis- The lower leaves of this species may appear whorled, but are comprised of opposite, ternately compound leaves. Dahlia imperialis, (inflorescence) (photos from Costa Rica)- This impressive species can grow over 10 ft tall with flowers to rival any garden Dahlia in beauty. Echinacea purpurea Purple Coneflower- This prairie native used in herbal medicine is native further west but is a widely planted ornamental in PA. Erigeron pulchellus Robin's Plantain- Although the disk flowers of this species are always yellow, the ray flowers range from white to blue-purple. Eupatorium coelestinum Wild Ageratum (Native to S. U.S.)- This pretty Eupatorium is often weedy in pastures, fields, and roadsides in the Southeast. Eupatorium fistulosum Hollow Joe-Pye Weed- This species may be told by its rounded inflorescence, hollow stem, and leaves in whorls of 6. Eupatorium maculatum, (closer) Spotted Joe-Pye Weed- Spotted Joe-Pye Weed stems may be purple or spotted. The leaves are usually in whorls of 4 or 5. The flat-topped inflorescence attracts clouds of insects, including many butterflies. Eupatorium purpureum Sweet Joe-Pye Weed- This species is usually found in more wooded areas rather than open meadows like other Joe-Pye Weeds. Eupatorium perfoliatum Boneset- The stems of this species seemingly pierce between the opposite, perfoliate leaves. Eupatorium rugosum White Snakeroot- Like other Eupatoriums, this woodland species has it's inflorescences in rayless heads. Eupatorium sessilifolium Upland Thoroughwort- This species is often found along edges of limestone woods. Euthamia graminifolia Grass-Leaved Goldenrod- This species is often included in the genus Solidago with other goldenrods. It is the common flat-topped inflorescence goldenrod-type plant in PA. Helianthus decapetalus Thin- Leaved Sunflower- This is the most common wild sunflower over most of PA. The ten or so "petals" are sterile ray flowers. Helianthus divaricatus Woodland Sunflower- Woodland Sunflower is a short Sunflower that often grows in open woods and edges. Krigia biflora Orange Dwarf Dandelion- Although called dwarf dandelion, this woodland species is native, unlike the common lawn weed. Perezia recurvata, (inflorecence) (photos from Patagonian Andes, Argentina)- Like Baccharis magellanicus this species survives the harsh Patagonian winds by growing in low, prostrate mats. The flowers are all ligulate. Prenanthes alba, (inflorescence) Rattlesnake Root- Members of the genus Prenanthes are sometimes called Lion's Foots because of the shape of the basal leaves, which may be present for years before the plant finally flowers. Rudbeckia laciniata Green-Headed Coneflower- This tall relative of Black-Eyed Susans has its disk flowers borne on a cone-like receptacle. Rudbeckia occidentalis Western Coneflower- (photo from Utah) A common plant of meadows and edges in the mountain West, unlike the "Black-Eyed Susans" in the same genus, this species lacks showy, yellow ray flowers. Rudbeckia triloba Brown-Eyed Susan- The species name triloba refers to the lower leaves, which are often three-parted. Senecio aureus Golden Ragwort- This spring bloomer is common in wet woods, slopes, and edges. The basal leaves are undivided. Silphium trifoliatum Whorled Rosinweed- This plant usually grows in dry soils, and can be found in Centre County on limestone prairie remnants. Solidago caesia Blue-Stemmed Goldenrod, Wreath Goldenrod- This is the most common woodland species in PA with axillary clusters of capitula. It is often found near Aster cordifolius and/or other woodland Asters. Solidago canadensis, (2) Canada Goldenrod- This is probably the most common old-field goldenrod in PA, although other very similar species are equally abundant in many areas. Solidago juncea Early Goldenrod- As its name suggests, this species is usually the earliest goldenrod to commence blooming in late summer, although the bloom period overlaps that of other species as summer wanes. Early Goldenrod often grows in dry areas where competing vegetation is minmal, allowing this species to form large basal rosettes of leaves that may store energy for several years before blooming. Solidago rigida, (2), (capitula) Stiff Goldenrod- More common further west in prairie states, Stiff Goldenrod is threatened in PA, where it growns in limestone grasslands. The individual flowers are large for the genus, making it perhaps the most attractive Goldenrod in PA. Solidago rugosa Rough Goldenrod- Rough Goldenrod shares the same pyramidal inflorescence with the other field species it co-occurs with, but most other species appear 3-nerved from the base of their leaves, whereas this species has normal pinnate veination on its roughly-toothed leaves. Solidago ulmifolia Elm-Leaved Goldenrod- This species grows in dry edges and woods and can be told by the cauline leaves, which are largest midway up the stem. Tussilago farfara Coltsfoot (non-native)- The flowers of Coltsfoot emerge on scaly stalks in early spring before the leaves, the shape of which gives it its name. Vernonia gigantea, (closer), (white form) Tall Ironweed- This late-blooming wildflower of wet fields and edges lacks ligulate ray flowers. The color of the pappus and shape of the scale-like bracts surrounding the clusters of purple flowers are useful in identification to species. *Campanulaceae: (Bellflower Family) Identification characteristics: Campanulaceae have alternate leaves and their flowers consist of 5 sepals, 5 fused petals, 5 stamens inserted on the corolla, and 2 to 5 fused carpels that form an inferior ovary. Lobelioids have zygomorphic flowers and stamens that are syngenesious above the base. Many Campanulaceae demonstrate plunger pollination in much the same manner as Asteraceae. Capsules are produced from the inferior ovary. All species in our range are herbaceous. Interesting stuff: If the flowers of some Campanulaceae are not pollinated within a few days, the stigmas will coil backwards until they make contact with pollen, effectively self-pollinating the plant. Each flower produces capsules with hundreds or even thousands of tiny seeds. Campanula americana Tall Bellflower- The blue flowers of this biennial species have protruding recurved styles. Campanula rotundifolia, (flowers) Harebell- This seemingly delicate plant grows out of the inhospitable environment of rock crevices and cliffs. Notice the bell-shaped, "Campanulate" flowers. Triodanis perfoliata Venus' Looking Glass- This purple-flowered annual forms a 3-angled capsule from the inferior ovaries; each side of the capsule has a pore that opens via a flap to release the seeds. The lowermost flowers are often cleistogamous. Lobelia cardinalis, (2) Cardinal Flower- This late summer plant has the most brilliant red flowers native to PA; they are a favorite of hummingbirds. It grows along streams and wetlands where flooding is common, as the tiny seedlings need bare ground with no competition to become established. Lobelia inflata Indian Tobacco- The leaves of Indian Tobacco are extremely bitter if chewed. This small-flowered species is sometimes weedy. Lobelia siphilitica, (flower closeup), (purple variant) Great Blue Lobelia- The inferior ovaries of these species produce thousands of dustlike seeds. The reproductive structures are highly modified and held above the zygomorphic corolla. Lobelia spicata Spiked Lobelia- This species often grows in dry, barren soils. There is a wide range of variation in flower size between populations.
*Caprifoliaceae: (Honeysuckle Family) Identification characteristics: The leaves of Caprifoliaceae are opposite and sometimes connate-perfoliate (see Lonicera dioica). The flowers have 5 fused petals, 5 stamens adnate to the corolla, and 2-5 carpels which form an inferior ovary. The flowers may be strongly zygomorphic to completely actinomorphic. Plants may be herbs, shrubs, or vines, and may produce dry capsules or fleshy berries. Interesting stuff: Caprifoliaceae has been split up and/or combined with various families recently based on molecular studies. Many, such as Viburnum and Sambucus are now transferred to the family Adoxaceae. Some authors separate capsule-forming shrubs into the family Diervillaceae, while others combine families such as Valerianaceae and Dipsacaceae with Caprifoliaceae. Diervilla lonicera Bush Honeysuckle- Unlike members of the genus Lonicera, this species has serrated leaves and capsules, rather than berries, for fruits. Lonicera dioica, (fruit) Wild Honeysuckle- This species tends not to climb as much as other viney honeysuckles, but is more twiney than the shrubby species. Note the connate perfoliate leaves below the flowers. Like many other Lonicera species, L. dioica produces brightly colored berries dispersed primarily by birds. Lonicera sempervirens Trumpet Honeysuckle- The hummingbird-pollinated flowers of this species are much less obviously zygomorphic than others in the genus. Sambucus canadensis, (closeup with Crab Spider) Elderberry- The purplish-black berries are often used for wine or jellies. It has opposite, pinnately compound leaves. Sambucus racemosa Red Elderberry- This species of rocky woods blooms in spring, earlier than S. canadensis, and the bright red berries aren't edible to humans. Viburnum acerifolium, (2) Maple-Leaved Viburnum- This species, also known as Dockmackie, produces blue-black berries in late summer. It grows in the understory of various woodland communities. Viburnum dentatum Arrowwood- This species is common around bogs, but may be found elsewhere as well. Some varieties are widely planted as ornamentals. |
