Date of trip: 10/10/2026 Time: 10AM Eastern Time Location: Scott’s Gap, Jefferson Memorial Forest, Jefferson Co., KY Difficulty of hike: Strenuous
Quercus marilandica from the trail
Join KNPS Field Trip Chair Alan Abbott for a hike in the Scott’s Gap section of Jefferson Memorial Forest. The hike explores some unusual xeric ridges within Metro Louisville.
In the driest parts, hikers will see Blackjack (Quercus marilandica) and Chinkapin Oaks (Quercus muehlenbergii), as well as Blueberries (Vaccinium sp.), Goldenrods (Solidago sp.), False Floxgloves (Agalinis sp.), and Dittany (Cunila origanoides). The trail provides some scenic views of south Louisville.
While the hike will only be two to three total miles, it will be strenuous, especially as the group follows the trail to the top of the knob. Participants should bring sturdy shoes, water and a snack, as well as tick protection.
To register for this field trip, fill out and submit the form below.
Field Trip Registration – 2026-10-10 – Field Trip to Scott’s Gap
Earlier this year [2019], I was working on a project surveying for rare plants and natural communities in the Big South Fork of Kentucky. Hidden in the biologically diverse region of the Cumberland Plateau, we share this region with Tennessee, where headwater streams flow north into Kentucky and create river scour communities along the Big South Fork of the Cumberland River. The Big South Fork is by far one of my favorite places on Earth. The diversity of species, both plants and animals, even undescribed taxon, is astounding. And the river scour communities within this region contain more globally rare plants than anywhere else in Kentucky! This species diversity is only compounded by the complexity of the riparian communities from emergent marshes, outcrops, grasslands, shrublands and woodlands that are maintained by the wild river scour. It’s one of the few places still left in Kentucky where pre-settlement natural conditions still exist, it’s as if you are seeing a landscape that was seen by Native Americans, a true wilderness. And this is also one of our states largest intact forest blocks. It feels ancient, diverse and wise.
Devils Jump , Big South Fork, Kentucky
A tale of Large flowered Barbara’s Button’s
Joining me on the Cumberland Plateau river scour botanical survey team this year were Kentucky Nature Preserves botanists Heidi Braunreiter and Devin Rodgers. This past May 2019, one of our main target species was Barbara’s buttons (Marshallia grandiflora), an elusive rare plant tucked away behind large boulders and cobble on the river scour of the Big South Fork. Marshallia is a genus in the aster family, and all the species within this genus occur in the southeastern United States. Marshalllia grandiflora is endemic to the Appalachians and the Cumberland Plateau, and is currently being assessed for federal listing. It is endangered in Kentucky and Pennsylvania, and threatened in Tennessee and West Virginia, and extinct in North Carolina. The habitat consists of diverse prairioid grasslands that occur on the river scour of several wild rivers. Associated plants of Marshallia consist of species you would find in a prairie such as big blue stem (Andropogon gerardii), Indian grass (Sorgastrum nutans), wild blue indigo (Baptisia australis), blazing stars (Liatris microcephala), sunflowers (Helianthus giganteus, H. hirsutus, H. decapetalus), tall coreopsis (Coreopsis tripteris), st. johns worts (Hypericum sp.), Obedient plant (Physostegia virginiana), goldenrods (Solidago sp.) and asters (Symphytrichum sp.).
large flowered Barbara’s buttons (Marshallia grandiflora)Large flowered Barbara’s buttons (Marshallia grandiflora)small blazing star (Liatris microcephella)wild blue indigo (Baptisia australis)wild potato vine (Ipomoea pandurata)obedient plant (Physostegia virginica)sensitive plant (Mimosa microphylla)
Large flowered Barbara’s buttons are very rare. In Kentucky, at the northern edge of its range in the Cumberland Plateau, this plant is extremely endangered and declining. When we were lucky enough to find a population, only a few single flowers or rosettes had survived. Many questions remain unanswered about this plants life cycle on the Big South Fork of the Cumberland River. How does this perennial stay rooted in the floods? How would seed produced ever have the chance to germinate? I would imagine a deep tap root or an abundance of lateral roots to anchor this plant during the floods, and an ability to live a long life (maybe even thousands of years old), but we just don’t know. And the mammal or bird dispersed seed taking root in the dry months of the summer, quickly sending its taproot to prevent it from being washed away in the next flood. Could a plant’s root break off during a flood, travel downstream and re root in suitable habitat, essentially replanting itself through vegetative reproduction? This is strategy is employed by the Cumberland rosemary (Conradina verticillata), but it is unclear weather Marshallia is able to do this. But a shift in flooding patterns, and changing climate, bring uncertainty and could prevent a seedling from taking hold. There are so many unknowns and confounding factors in the life cycle of this plant.
Large flowered Barbara’s buttons (Marshallia grandiflora)
Life on the river scour can be harsh. Brutal even. For both its inhabitants as well as surveyors like ourselves. There are copperheads and rattlesnakes hiding within these prairies, with massive boulders and logjams slowing our travel. Bouldering and rock hopping is necessary to navigate the jumbled debris. With the rains come floods that roar through the gorge, scouring everything in its path. It’s amazing to me that anything can survive that. But it is this very disturbance that maintains these “prairies of the river,” for without the flooding and scour, shrubs and trees would take hold and the prairie grasses and forbs would disappear. Couple this flooding with summer droughts to keep the trees and shrubs at bay, and the river prairies thrive. Dam these rivers and everything disappears.
Braunreiter and Littlefield crossing the Big South Fork
Rodgers exploring the large boulders of the river scour
Little is known about how long these plants have been hiding out amongst the boulders of the river scour. Likely these disjunct populations from Pennsylvania to Tennessee were connected in the ancient Appalachian landscape. Probably they were more common, and may have evolved within a much more expansive upland ancient prairie habitat that has long ago vanished due to natural large scale climate change, as well as a more connected river scour habitat that is now nearly lost due to damming of rivers and degradation of plant communities from invasive plants, loss and alteration of disturbance regime, and a changing climate. There is even new research into the genetic differences among the extinct North Carolina populations with the rest of the population range, suggesting that there are two different species uniquely evolved in isolation. So what is our role in conserving this unique species? One can only speculate that this species is an ancient plant of a lost world, perhaps evolved in in the ancient upland grassland habitat, but now only found in sheltered ravines codependent on the floods of our protected wild rivers to maintain its habitat and ensure its further existence.
Large flowered barbara’s buttons (Marshallia grandflora)
Other interesting rare plants that we encountered on the river scour this year include the globally rare Rockcastle aster (Eurybia saxicastellii), Balsam ragwort (Packera paupercula var. paupercula), Turk’s-cap lily (Lilium superbum), golden club (Orontium aquaticum), the federally threatened Cumberland rosemary (Conradina verticillata) and the boulder bar goldenrod (Solidago racemosa). Included in the mix are intriguing mysteries of possible news species. But there is one rare plant that we encountered on the river scour that has always intrigued me by its glacial relict past, as it seemed to tell the story of these lost worlds with more clarity, of large scale plant migrations over spatial time that us humans can only begin to comprehend, the sweet fern (Comptonia perergina).
Rockcastle Aster (Eurybia saxicastellii)Turk’s cap lily (Lilium superbum)Cumberland rosemary (Conradina verticillata) Balsam ragwort (Packera paupercula var. paupercula)
Sweet Fern-an ancient glacial relict plant lost in the
south
The wax myrtle or bayberry family
(Myricaceae) is known for its odor. These
plants have resinous dots on their leaves, making them aromatic. Plants in this family have a wide
distribution, including Africa, Asia, Europe, North America and South America,
missing only from Australia. Myricaceae
members are mostly shrubs to small trees and often grow in xeric to swampy
acidic soils. Familiar members of the
wax myrtle family include many in the Genus Myrica
(sweet gale, wax myrtle), some of which are used as ornamentals and are
economically important. In addition, the
wax coating on the fruit of several species of Myrica, has been used traditionally to make candles.
So what place does this
interesting family have in Kentucky’s flora?
We are lucky to have one species in the wax myrtle family, sweet fern (Comptonia peregrina). In addition, it is also a monotypic genus
restricted to eastern North America meaning the genus Comptonia has only one species (C.
peregrina) worldwide, and we are lucky it is found here in Kentucky!
The common name sweet fern is
misleading. This woody shrub is
certainly not a fern. However, the
leaves have a similar shape to pinnules of a fern frond. But having sweet in the common name is no
mistake. If you crush the leaves, a
lovely smell is emitted as the essential oils volatilize into the air.
Sweet fern is a clonal shrub that
grows up to one meter high and spreads through rhizomes. The leaves are
alternate and simple, linear and coarsely irregularly toothed, dark green above
and a bit paler below. It is monoecious
meaning male and female flowers occur on different plants. The female flowers are not showy—short
rounded catkins that are dense cluster of apetalous flowers, usually associated
with oaks, birches and willows with reddish bracts. The male flowers are elongated yellow-green
catkins clustered at the branch tips, the pollen being adapted to wind
dispersal. The fruit is a round,
bur-like cluster of ovoid nutlets that turn brown when mature in late
summer. The bark is reddish and highly
lenticeled with small corky pores or narrow lines on the bark that allow for
gas exchange.
Sweet fern catkins on the Big South Fork
Sweet fern (Comptonia peregrina)
While common in the northern
part of its range (northeastern United States and Canada), sweet fern is state
listed endangered in Kentucky, along with being state listed as rare in Ohio, Tennessee,
South Carolina, West Virginia, Georgia, and North Carolina. The populations of sweet fern in the southern
part of its range are isolated and disjunct from the common habitats up north. There seems to be a close association of
these remnant populations with the Appalachian Mountains, which suggests that
the populations in the southern ranges remained in protected “refugia” during
periods of great plant migrations that followed glacial cycles.
Sweet fern (Compotonia peregrina) range
Sweet fern is typically found
in openings in coniferous forests with well drained dry, acidic sandy or
gravely soils with periodic disturbances.
In the north, it can be found in pine-oak barrens or jack pine and spruce
forests that are maintained by fire, creating openings and decreasing
competition. It has also been noted to
colonize road banks and even highly disturbed soils such as mined areas. Contrary to these open coniferous habitats
with periodic fire, the remnant populations of sweet fern in Kentucky and
Tennessee are found on sandstone cobble bars, which are maintained by annual
floods. Despite being found on habitats
that are maintained by different disturbance regimes, these two communities
share a few things in common—they are both dry, acidic, sandy and nutrient
poor. Disturbances are a natural
occurring impact in these communities that removes shrubs and saplings, thus
decreasing competition so that sweet fern can thrive.
Sweet fern on the sandstone cobble bars
But perhaps the most fascinating
facts about the rare shrub sweet fern is what it can tell us about the
evolution of plants, the history of the earth, and the paleovegetational past
of Kentucky. Geologically speaking,
sweet fern is an ancient plant. In
Kentucky, it was likely more common 20,000 years ago during the last glacial
period, as Kentucky’s climate was much more like present day Canada. Analysis of pollen in sediment cores taken
from natural ponds in Kentucky confirms that spruce and jack pine was common in
the uplands in the bluegrass. Sometimes
it is difficult to imagine plants migrating north and south in order to adapt
to a changing climate. But what is even
more mind blowing is that the genus Comptonia
is at least 65 million years old.
Numerous fossils of dozens of extinct species of Comptonia have been found all across the Northern hemisphere, and the
earliest of the fossils have been dated back to the Cretaceous period during the
age of the dinosaurs. The first flowering plants evolved only 135 million years
ago, making Comptonia is one of the
oldest living plants in the world—a true living fossil!
When April 2020 comes around,
and all of the spring wildflowers are emerging, think of sweet fern tucked deep
into the gorges of Big South Fork, its catkins releasing pollen in the wind, think
of Barbara’s buttons withstanding the massive seasonal floods of one of Kentucky’s
last wild rivers. And if you use your
imagination, you may be also be able to see dinosaurs and tree ferns in the
distance. Let us hope sweet fern and Barbara’s buttons
can survive for many millions of years to come.
The Lady Slipper newsletter, and now blog, of the Kentucky Native Plant Society has been published since the Society’s founding in 1986. We occasionally feature an article from a past issue. In this article from 2007, Amy McIntosh discusses members of the Birthwort Family, Aristolochiaceae . This article ran in Vol. 22, No. 2. If you would like to see these and other past issues, visit the Lady Slipper Archives, where all issues from Vol. 1, February 1986 to Vol. 40, 2025, can be found.
Aristolochiaceae: Insects, Humans and the Birthwort Family
by Amy McIntosh
Introduction
Members of the Birthwort Family, Aristolochiaceae, have a complex array of relationships with insects and humans. Interactions with pollinators, non-pollinating butterflies, and seed/fruit dispersers (along with the plants’ pollination mechanisms and the creation and use aromatic oils) provide insight into the family’s co-evolution with insects.
Human relationships with the birthwort family have a long history involving herbal and food use. Current interests in the family include collection of garden and greenhouse specimens, breeding of ornamental varieties and determining effectiveness of possible anticancer chemicals within some species. Human degradation of habitat in areas of endemic and otherwise limited populations has threatened 35 species at last count.
Asarum canadense, photo by Amy McIntosh
Attracting Pollinators
Unlike some flowering plants that boast a bright, colorful perianth, most Aristolochiaceae members possess green, brown, black, deep purple or pale yellow calices (Huber 1993). Some members of the family utilize self-pollination as the major means of sexual reproduction (e.g., Asarum europaeum European wild ginger) (Huber 1993). Aristolochia serpentaria (Virginia snakeroot) is suspected to exhibit cleistogamy (propagation by means of closed, self-pollinating flowers) (Pfeifer 1966). Others have flower maturation that restricts self-pollination temporally (for example, Aristolochia maxima (Florida dutchman’s pipe) is protogynous (explained below)) (Sakai 2001).
Species of Aristolochiaceae which are dependant on pollinators attract true flies (Diptera), beetles (Coleoptera) and thrips (Thysanoptera) with odor and floral food rewards (Sakai 2001). Warmth is an attractant as well (Thein et al. 2000). The lack of colorful flowers and the presence of floral odors suggest the early evolution of the family among angiosperms (Pellmyr and Thien 1986).
Floral odors
Hexastylis arifolia, photo by Amy McIntosh
Aristolochiaceae flowers generally emit strong, fetid floral odors mimicking musky fruit, fungus, urine, feces or carrion (Huber 1993; Sakai 2001; Cronquist 1981). In some carrion-scented flowers it is suggested that this scent is evidence of an adaptation to attract unsuspecting pollinators that originally fed and oviposited on carrion but now utilize floral tissues (Pellmyr and Thein 1986). Aristolochia grandiflora (pelicanflower, an exotic growing in Florida) was noted (on a label of a herbarium specimen deposited at the New York Botanical Gardens) as having a “strong odor of putrid meat [that] attracts the insects 100 or more feet from the flower” (Reis and Lipp 1982). The odors produced by early angiosperms (such as Aristolochiaceae) may even trigger insect mating (Pellmyr and Thein 1986).
Thermogenesis
Aristolochiaceae flowers produce heat through biochemical processes (called thermogenesis). Maximum heat production is synchronized with the stigma(s) ability to receive pollen. This production of heat is theorized to benefit basal angiosperms in many ways including enhancing floral odor release and pollen germination. The warmth also benefits pollinators by conserving the insects’ energy and providing a good environment for breeding and development of larvae (Thein et al. 2000).
Flower rewards
Floral tissues are rich in energy and provide a competitive edge for ovipositing female insects and resulting larvae (Pellmyr and Thein 1986). Hexastylis is pollinated by thrips (Thysanoptera), which eat pollen grains and flower epidermal tissue. Thrips spend most of their life cycle within the flowers (USFW, 1990), (Sakai 2001). Two species of Aristolochia flowers (A. maxima and A. inflata) are known to provide ovipositing substrate for pollinators. The pollinators of these two flowers are predominantly female, indicating a coevolved link between the reproduction of the insects and plants (Sakai 2001).
Diptera (true flies) have specialized mouthparts that allow the imbibing of sweet floral liquids that are found on basal angiosperms’ stigmas, ovaries and stamens (Thein, et al. 2000). Although flies of several families are known to pollinate Aristolochia, the attraction is usually deceptive, and nectar and similar liquids may or may not serve as a reward depending on the plant species. These liquids may serve an alternative role in attraction, feeding the pollinator only during entrapment, or simply in attaching pollen grains to the insects’ bodies (Sakai 2001).
Pollination Mechanisms
In addition to these means of attracting pollinators, many Aristolochiaceae flowers are equipped with mechanisms that assist in insect pollination: floral traps and protogynous floral maturation. Floral trapping techniques allow for entrance and retention of a potential pollinator until the flower has been pollinated. This is accomplished by utilization of stiff directional hairs in the perianth tube leading to the utricle and/or an oily covering on epidermal cells which prevents traction (Huber 1993). Such trapping utricles limit competition for flower rewards and provide a safe haven for mating insects (Pellmyr and Thein 1986).
Protogynous flowers (observed in Aristolochia species) have “female” and “male” stages (days). On the first (female) day, the flowers may emit an odor to attract pollinators. The female organs are mature and prominent; stigmas are able to accept pollen and heat is produced inside the utricle. On the second (male) day the anthers become prominent and dehisce, covering the trapped insect with pollen. Subsequently perianth tube hairs wither and allow for the insect’s movement to another female-day flower in need of pollination (Pfeifer 1966; Hickey and King 1998).
Food Plant use by Papilionidae
Pipevine swallowtail caterpillar, photo by Amy McIntosh
Several genera of Papilionidae (swallowtail) butterflies utilize Aristolochiaceae for food plants. In fact, entire swallowtail tribes (Serynthiini and Troidini) are host specific to Aristolochiaceae. Caterpillars that feed on Aristolochiaceae plants are able to utilize aristolochic acids as predator deterrent (Tree of Life 2004).
Pipevine swallowtail, photo wc.pima.edu
In North America Battus (pipevine swallowtails) predate on Aristolochia species. Several genera of the Papililionidae are parasites on Asian Aristolochiaceae species. Archion and Zerynthia are distributed in the western palaearctis with their host plants. Bragantieae and some Aristolochia are eaten by Troides species (Huber 1993).
The swallowtail butterfly has two broods a year; the larvae consumes all of the foliage of the plant on which it emerges and seeks additional host plant individuals. Such ravenous feeding by the larvae results in lower plant reproduction success. These selective forces, over time, have resulted in adaptations by some species to prevent herbivory: tough leaves low in nutritional value and taste; high root-shoot ratios to store food for high predation years; and underground flower and fruit production (which are preferred to foliage by the insects) (Rausher and Feeny 1980).
Seed/Fruit dispersal
Aristolochiaceae utilizes a variety of fruit and seed dispersal mechanisms. Like many other temperate woodland herbs, ant-plant mutualism (called myrmecochory) plays an important role in the distribution of herbaceous species’ seeds (notably Asarum and Hexastylis). Aristolochia is dispersed by wind after fruits dehisce. Sticky seeds, edible fruit and water dispersal are alternative means of dispersal utilized by the family.
Hexastylis seeds have copious eliasomes (fat bodies) which are readily eaten by ants. In fact, Gaddy (1986) noted consistent 100% removal rates of Hexastylis seeds by ants in experiments where a wide range of seed types were made available. This rich food source results in hoarding of the seeds at ant nest sites, where germination in clusters occurs the following spring (USFW, 1990). Similar observations have been made of Asarum europaeum seeds, which are dispersed by Formica polyctena (Gorb and Gorb 2003).
Asarum (wild ginger) seed are prone to desiccation (Kelly 1998). This coupled with dispersal limitations of myrmecochory may play a role in limited range of Asarum (in comparison to Aristolochia).
Many Aristolochia species have winged seeds that are dispersed when the fruits dehisce (Huber 1993). Some additional groups are distributed by animals: Aristolochia by means of sticky seeds that attach to animal bodies and Paristolochia by encouraging consumption of fragrant, edible fruits (Huber 1993). Aristolochia clematitis (birthwort) and two Amazonian species of the family possess fruits and seeds that are adapted for distribution by water (by means of floating) (Wulff 1943; Huber 1993). Aristolochia’s variety of dispersal techniques which favor a longer-distance results can help to explain the group’s wide distribution, including colonization of many isolated islands in Central America and Asia.
Human History of Medicinal Use
Members of the Aristolochiaceae have a long history of medicinal use, as evidenced by the inclusion of Aristolochia clematitis in medieval woodcut-illustrated herbals and commonly in later engravings. In fact, the name Aristolochia has roots in the Greek: Aristos (meaning best) and lochia (meaning delivery/birth) (Pfeifer 1966). Pliny referenced the use of Aristolochia by midwives, and termed it aristi lekhousais (translated—best for women giving birth) (Coffey 1993). The common name of Aristolochia clematitis further recognizes this common use of the “herb”. In addition, in keeping with the Doctrine of Signatures, the flower bud of members of Aristolochia was determined to resemble the human fetus or swollen womb and was utilized accordingly to remedy the pain of childbirth (Pfeifer 1966), and as an abortive agent, conception aid (and, ironically, preventative), and birth inducer (Coffey 1993).
Aristolochiaceae members have been determined in the past to possess many additional medicinal benefits. The family’s widespread use for a myriad of ailments is indicated by the use of its name by an honorary society of herbalists in the United States—The Aristolochite Society (now known as Rho Chi) (Pfeifer 1966). Aristolochia serpentaria (of North America) was prized as an antidote for snakebite, with records of this fact dating as early as 1633 (Coffey 1993). A. schippi (Honduras) and A. trilobata (Martinique) were used similarly for snakebikes, and Aristolochia bracteolata (of Tropical East Africa) for snakebite and scorpion stings (Reis and Lipp 1982; Verdcourt 1986). In keeping with a strong Chinese awareness of potential uses of herbs, Chapman and Wang (2002) list Aristolochia debilis as possessing antirheumatic, and diuretic properties. Other historical uses of the Asarum and Aristolochia include to cure ulcers, syphilis, rheumatism, cholera, relieve toothache, fever, indigestion, coughs, heart conditions, throat ailments, cramps, gas and to promote sweating (Foster 2000; Coffey 1993)
Recent research has shown that medicinal usefulness of the plants is not unfounded. Asarum’s rhizomes contain essential oils (sesquiterpenes and phenlypronanoid compounds), and aristolochic acid from aporphines is found in Tribe Bragantieae and Tribe Aristolochieae members (Huber 1993). These agents are currently being researched for anti-cancer and antibiotic properties, although the family also bears a reputation of possessing poisonous and carcinogenic properties (Foster 2000; Coffey 1993; Polunin 1969).
Non-medicinal Uses
Aristolochia tomentosa www.missouriplants.com
Aristolochiaceae members have been utilized for a variety of non-medicinal applications. Fruits, leaves, rhizomes and stems of the Aristolochia debilis were suggested in a circa 1406 AD list (the Chiu Huang Pen Tsao) as famine foods (Chapmand and Wang 2002). Aristolochia bracteolata (Africa) is reportedly used for food as well (Verdcourt 1986). Wild ginger (Asarum canadense of North America) has been known as a substitute for true tropical ginger (Zingiber spp.) (Coffey 1993). Pararistolochia (Aristolochia) triactina is used as a rope for various applications including binding hut materials in its native Uganda, Angola and nearby countries (Verdcourt 1986). A. daemoniana shares a similar use in British Guiana (Reis and Lipp 1982).
The unusual flower shape in many Aristolochia species have made them prized for ornamental use. Aristolochia gigantea (Brazilian dutchman’s pipe) and A. littoralis (calico flower) are common greenhouse tropicals and A. macrophylla (Dutchman’s pipe) is grown in many temperate gardens of the world (Pfeifer 1966). Aristolochia and Asarum species have been manipulated through hybridization to produce large, showy and unusual forms for collector-gardeners in many parts of the world.
Aristolochiaceae in Kentucky
Hexastylis contracta photo by James Kiser
Kentucky boasts eight species of the birthwort family, including representatives of three genera. Dutchman’s pipe (Aristolochia macrophylla) is a woody vine of mixed mesophytic forests and can be found growing to diameters exceeding 2 1/2”. Pipe-vine (A. tomentosa), is also a lianas, but inhabits swamps and wet woods of the Mississippi embayment.
Virginia snakeroot (A. serpentaria), a herb, completes the state’s constituents of the Aristolochia genus. Wild ginger, Asarum canadense, is common in moist woods throughout Kentucky and varies in floral color from greenish to deep burgundy with a wide range of sepal length.
In Kentucky the heartleaf and little brown jugs (genus Hexastylis) are restricted to the Appalachian region. One species, H. arifolia is relatively common, but the other three species, H. virginica, H. contracta, and H. heterophylla, are all rare and state-listed (Jones 2005).
Outlook for Aristolochiaceae
According to the World Conservation Monitoring Centre (1997), 35 Aristolochiaceae species are included on “red list” of threatened plants. These include four species and one variety found in the southeast of the United States: Hexastylis contracta (KY, NC,TN), H. naniflora (NC, SC), H. rhomiformis (NC), H. speciosa (AL), and H. shuttleworthii var. harperi (AL, GA).
Although some species of the family have been heavily harvested in the past for medicinal use (Coffey 1993), this threat has mostly subsided. High endemism (including some island endemism) and small ranges for many species make even minimal habitat destruction have an enormous impact.
Continued habitat degradation for agriculture and timber harvesting in tropical region impose a significant threat to much of the Aristolochieae tribe. Other potential concerns are present for species highly coevolved with pollinators and seed dispersers if insect populations are reduced.
Literature Cited
Chapman, G. P. and Y. Z. Wang. 2002. The plant life of China: Diversity and Distribution. Springer-Verlag, New York. 256 pp.
Coffey, T. 1993. The history and folklore of North American wildflowers. Facts on File, Inc. New York. 356 pp.
Cronquist, A. 1981. An integrated system of classification of flowering plants. Columbia University, New York. 1262 pp.
Foster, S. and J. A. Duke. 2000. A field guide to medicinal plants and herbs of eastern and central North America. 2nd edition. Houghton Mifflin Company, New York. 411 pp.
Gaddy, L. L. 1986. Twelve new ant dispersed species from the southern Appalachians. Bulletin of the Torrey Botanical Club. 113:3:247-251.
Gorb, E. and Gorb, S. 2003. Seed dispersal by ants in a deciduous forest ecosystem: mechanisms, strategies, adaptations. Kluwer Academic Publishers; Boston, Massachusetts. 225 pp.
Hickey M. and C. King. 1988. 100 families of flowering plants, 2nd ed. Cambridge University Press, Cambridge. 619 pp.
Huber, H. 1993. Aristolochiaceae. Pages 129-137 in Kubitzki, K., ed. The families and genera of vascular plants. Volume 2: Flowering Plants—Dicotyledons—Magnoliid, Hamamelid and Caryophyllid Families. Springer-Verlag, New York.
Jones, R. L. 2005. Plant life of Kentucky. University of Kentucky Press: Lexington, Kentucky. 834 pp.
Kelly, L. M. 1998. Phylogenetic relationships in Asarum (Aristolochiaceae) based on morphology and ITS sequences. American Journal of Botany. 85(10)454-1467.
Pellmyr O. and L. B. Thien. 1986. Insect reproduction and floral fragrances: key to the evolution of angiosperms? Taxon 35:76-85.
Pfeifer, H. W. 1966. Revision of the north and central American hexandrous species of Aristolochia (Aristolochiaceae). Annals of the Missouri Botanical Garden. 5:2:115-196.
Polunin, O. 1969. Flowers of Europe. Oxford University Press, London. 662 pp.
Rausher, M. D. and Feeny, P. 1980. Herbivory, plant density, and plant reproductive success: the effect of Battus Philenor on Aristolochia Reticulata. Ecology. 61(4): 905- 917.
Reis, S. V. and F. J. Lipp, Jr. 1982. New plant sources for drugs and foods from the New York Botanical Garden Herbarium. Harvard University Press: Cambridge, Massachusetts. 363 pp.
Sakai, S. 2001. Aristolochia spp. (Aristolochiaceae) pollinated by flies breeding on decomposing flowers in Panama. American Journal of Botany. 89(3)527-534.
Thien, L. B. et al. 2000. New perspectives on the pollination biology of basal angiosperms. International Journal of Plant Sciences. 161(6 suppl.)225-235.
Tree of Life web project. http://tolweb.org/tree/ phylogeny.html. Accessed 12/06/04.
Asarum caudatum, by A. R. Valentien
U. S. Fish and Wildlife Service Division of Endangered Species. Dwarf-Flowered Heartleaf (Hexastylis naniflora). Endangered and Threatened Species of the Southeastern United States (The Red Book). FWS Region 4. http:// endangered.fws.gov/i/q/saq5g.html. Accessed 11/23/ 2004.
Verdcourt, B. 1986. Aristolochiaceae. Flora of Tropical East Africa series. Royal Botanic Gardens, Kew. 11 pp.
World Coservation Monitoring Centre. 1997 IUCN Red List of Threatened plants. http://www.wcmc.org.uk. Accessed 11/28/04
