Regularity: Regularly occurring
Global Range: Historically, ranging through the tallgrass prairie region from northwestern Indiana, southwestern Wisconsin and southern Iowa to southern Illinois, southern Missouri and eastern Kansas. Currently extant in eastern Kansas, west-central Missouri, south-central Iowa and eastern Illinois.
U.S.A. (IA, IL, IN, KS, MO, WI)
Localities documented in Tropicos sources
United States (North America)
Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.
- Anonymous. 1986. List-Based Rec., Soil Conserv. Serv., U.S.D.A. Database of the U.S.D.A., Beltsville. http://www.tropicos.org/Reference/1103
- Gleason, H. A. 1968. The Sympetalous Dicotyledoneae. vol. 3. 596 pp. In H. A. Gleason Ill. Fl. N. U.S. (ed. 3). New York Botanical Garden, New York. http://www.tropicos.org/Reference/1707
- Great Plains Flora Association. 1986. Fl. Great Plains i–vii, 1–1392. University Press of Kansas, Lawrence. http://www.tropicos.org/Reference/637
- Fernald, M. 1950. Manual (ed. 8) i–lxiv, 1–1632. American Book Co., New York. http://www.tropicos.org/Reference/1327
- Woodson, J. R. E. 1954. The North American species of Asclepias L. Ann. Missouri Bot. Gard. 41(1): 1–211. http://www.tropicos.org/Reference/7133
Stem to 2 ft, smooth, containing milky sap. Leaves opposite, simple, narrowly to broadly lance-shaped, toothless, without stalks. Flowers borne in solitary drooping umbel at end of a long stalk. Corolla greenish white, hoods purple or greenish purple. Flowers open in late May and early June.
Comments: In pre-European settlement times, A. meadii possessed a wide distribution, ranging through the tallgrass prairie region from northwestern Indiana, southwestern Wisconsin and southern Iowa to southern Illinois, southern Missouri and eastern Kansas (Betz 1989). Historic records are known from 47 counties in six states: Illinois, Indiana, Iowa, Kansas, Missouri and Wisconsin (Chaplin et al. 1990). Today, the species has been extirpated from much of its former range and has been significantly reduced in abundance elsewhere. It is currently known from 127 sites in 27 counties in eastern Kansas, west-central Missouri, south-central Iowa and eastern Illinois (Chaplin et al. 1990).
Mead's milkweed is a species of dry-mesic to mesic tallgrass prairies (Chaplin et al. 1990) a community which is climate and fire-adapted and maintained (Barbour and Billings 1988, Axelrod 1985). The species has also been recorded from chert glades (Steyermark 1977) and sandstone rock-ledges (Voigt and Mohlenbrock 1964). Plants seem to prefer full sun, occupying slopes that grade between 0 and 18% (Chaplin et al. 1990). For additional information pertaining to habitat, see Chaplin et al. (1990).
Associates include a lengthy list of over 60 prairie plants (Betz 1989). Among the associates are Achillea millefolium, Amorpha canescens, Andropogon gerardii, A. scoparius, Antennaria neglecta, Asclepias viridis, A. tuberosa, Baptisia bracteata, Coreopsis palmata, Dalea candida, D. purpurea, Desmanthus illinoensis, Dichanthelium oligosanthes, Echinacea pallida, Erigeron strigosus, Eryngium yuccifolium, Liatris pycnostachya, Lithospermum canescens, Lobelia spicata, Phlox pilosa, Polytaenia nuttallii, Psoralea tenuiflora, Ratibida pinnata, Scleria triglomerata, Silphium laciniatum, Sisyrinchium campestre, Sorghastrum nutans, Sporobolus heterolepis, Tripsicum dactyloides, and Viola pedatifida (Chaplin et al. 1990, Betz 1989).
In eastern Kansas, A. meadii occurs in Allen, Anderson, Bourbon, Coffey, Douglas, Franklin, Jefferson, Leavenworth, Miami and Linn Counties (McGregor 1987). Populations occur predominantly on the unglaciated terrain of the Kansas River (Chaplin et al. 1990). The majority of known sites are on limestone bedrock, with two exceptions occurring over sandstone (McGregor 1987). These sites are typically well-drained to excessively drained with silty-loam mollisol soils derived from loess residuum, limestone, shale, glacial till or sandstone (Freeman 1988). Populations typically occur in upland tallgrass prairie sites. At such sites, associates frequently include the western prairie fringed orchid and the prairie mole-cricket (Gryllitalpa major) (Busby 1990, Figg and Calvert 1987). A small population was recently discovered on a sandstone prairie which was invaded heavily by Quercus marilandica, Q. stellata, and Juniperus virginiana (Chaplin et al. 1990).
Four populations of A. meadii occur in tallgrass prairie and dry barrens in Illinois (Kurz and Bowles 1981). Three populations occur in southern Illinois in the unglaciated Shawnee Hill Division (Mohlenbrock 1986) along a single sandstone escarpment (Schwegman in litt.). The fourth population occurs in the glaciated portion of east-central Illinois known as the Grand Prairie Division (Mohlenbrock 1986). In the sand barrens of Illinois, trees associated with A. meadii include Quercus marilandica, Q. stellata, Q. velutina, and Juniperus virginiana. Other associated prairie species include: Allium canadense, Anemone cylindrica, Apocynum sibiricum, Aster ericoides, Aster laevis, Cirsium discolor, Convolvulus sepium, Fragaria virginiana, Helianthus maximilliana, Lithospermum canescens, Petalostemum purpureum, Poa compressa, Polygala senega, Sisyrinchium albidum, Solidago rigida, Sporobolus heterolepis, and Stipa spartea (Swink 1974, Litzow 1978, Kurz and Bowles 1981).
Steyermark (1977) stated that A. meadii was rare and local in the southern half of Missouri, occurring in dry upland prairies and chert-lime glades. Currently, all populations (42) occur within the unglaciated Osage Plains region in west-central Missouri (Morgan 1980). Most populations are on mollisols and alfisols which formed over loess, glacial till, limestone, sandstone and shale (Morgan 1980).
In Iowa, A. meadii is restricted to four sites: Woodside Prairie (Adair County), Flaherty Prairie (Clarke County) and Churchville and Cumming Prairies in Warren County (Leoschke pers. comm.), all of which occur within the Southern Iowa Drift Plain (Prior 1976). All populations are comprised of 10 or less genets (Leoschke pers. comm.). Two of the extant mesic tallgrass prairie sites occur along railroads (IA NAI 1990). Extant populations occur on clay-loam and silty clay-loam mollisols developed from weathered Kansas age drift covered with a moderate to thick layer of loess (Freeman 1988). Woodside Prairie in Adair County, one of the best remaining prairies in southern Iowa, occurs on Adair clay loam with 5-9% slopes (IA NAI 1990).
A single historic record of A. meadii exists from Indiana, collected near Crown Point on dry ground in 1888 (IN NHP 1989). No extant populations are known from the state (Homoya 1989). Similarly, the sole historic population known from Wisconsin has been extirpated (Braker pers. comm.).
Flower-Visiting Insects of Mead's Milkweed in Illinois
(Insects seek nectar; observations are from Betz et al.)
Apidae (Apinae): Apis mellifera; Apidae (Bombini): Bombus affinis, Bombus griseocallis; Anthophoridae (Anthophorinae): Anthophora abrupta
Known Pests: Beetle larva (Curculionidae) in stalk; larvae of Tetraopes femoratus (destructive to root system)
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 81 - 300
Comments: 222 occurrences (seen since 1992) in eastern Kansas, west-central Missouri, south-central Iowa and eastern Illinois. Of those, 59 have EO rank of A, B, or C.
Asclepias meadii is a polycarpic perennial (Chaplin et al. 1990) and requires five to eight years to reach maturity from seed (McGregor pers. comm., Betz and Hohn 1978). Plants appear to be long-lived and may live for more than a century (Betz and Hohn 1978).
Mead's milkweed reproduces sexually through seed production and vegetatively through spreading rhizomes (Chaplin et al. 1990). Sexual reproduction in A. meadii is apparently rare (Kurz and Bowles 1981), due to a number of factors. Betz (in litt.) found that only 15% of all flowers succeeded in producing fruit in Illinois. McGregor (pers. comm.) found only 10% successful fruit production in plants observed in Kansas. In addition to low fruit set, seed viability within A. meadii fruits is typically low and may attribute significantly to the low fruit production found in extant populations (Betz 1988). Roughly half (52.4%) of all seeds found were found not to be viable. Finally, the extremely low A. meadii population numbers present at some sites may make it additionally difficult for the inflorescences to attract potential pollinators (Betz and Hohn 1978). Without satisfactory pollination, fruit and seed set does not occur. Continued fragmentation and loss of habitat may further decrease the sexual reproduction success.
Although asexual reproduction is known in A. meadii, little specific information has been accumulated with regards to specific means. The number of rhizomes produced per genet and the extent to which they spread is unknown (Chaplin et al. 1990). The rhizomatous nature of the species has likely sustained it in habitats where mowing (and the subsequent removal of seeds) was a frequent regime (Freeman 1988).
Pollen is shed by pollinaria (Bookman 1981) which are disseminated by insects (Chapman et al. 1990). Relatively few insects have been observed on A. meadii plants, however (Betz 1989). Common inhabitants of the foliage include the milkweed bug (Oncopeltus fasciatus), the lesser milkweed bug (Lygaeus kalmii) and the caterpillar of the monarch butterfly (Danaus plexippus). Other insects associated with A. meadii include the cerambycid milkweed beetle (Tetraopes femoratus), common milkweed beetle (T. tetraophthalamus) and milkweed weevils (Rhyssematus annectans and R. lineaticollis). Potential pollinators include bumblebees (Bombus affinis and B. griseocollis) and digger bees (Anthophora raui) (Betz 1989).
A two-week difference in flowering time between plants in the south (southern Kansas and Missouri) and the north (northern Illinois) has been noted (Schwegman 1988, Betz 1967). In southern Illinois, A. meadii emerges between April 11-23 and demonstrates slow growth until about 6 cm tall. Between May 15 and June 3 there is rapid stem elongation until mature height (about 0.6 m). Flowering frequently occurs between May 21 and June 18. Single fruits develop from each inflorescence, the follicles or pods observable by late June. By late August the pods have elongated to their maximum size (4 to 8 cm) and are greenish in color. These darken as the fruits mature and dehisce in mid-September to mid-October to release the numerous, hairy seeds. The plants begin to wither with first frosts, and are no longer visible by early November (Biotic Consultants 1976).
Given populations of A. meadii may vary in size annually (McGregor pers. comm.). In 1981, a population near Lawrence had 14 plants in flower; In 1982, the same colony had over 100 plants in flower and many non-flowering stems. The explanation for the advent of this proliferation of flowering is not known. Although populations may vary in size from year to year, census data suggests that most populations remain fairly constant (Freeman 1988).
Betz (in litt.) reported that germination of A. meadii is best accomplished through cold stratification of seeds in damp plastic bags at 40 degrees Fahrenheit for a period of 8 weeks. Seedlings grow slowly and remain spindly for 2 or 3 years (Betz pers. comm.). McGregor (pers. comm.) planted seeds in the 1950's and found that it took seven years for a plant to mature and produce flowers. Betz (pers. comm.) reported that 5 to 7 years may be necessary between germination and flowering. Aphids can be a potential problem in young plants (Betz 1978), while seedlings are apparently very susceptible to damping-off (McGregor pers. comm., Betz pers. comm.).
Willson and Price (1980) studied resource limitations in other Asclepias species (A. syriaca, A. verticillata, and A. incarnata). They found that the addition of mineral fertilizer increased the numbers of mature pods per stem in A. syriaca and A. verticillata, and the numbers of seeds per pod and seed weight in A. syriaca. Defoliation tended to reduce the numbers of mature pods per stem of all three species. Shading has a similar, but less noted, effect (Willson and Price 1980).
Life History and Behavior
Persistence: PERENNIAL, Long-lived
NatureServe Conservation Status
Rounded Global Status Rank: G2 - Imperiled
Reasons: A formerly widespread species - historically it ranged over much of the native tallgrass prairie region of the Midwest - that has declined due to the extensive destruction and fragmentation of its habitat. Where habitat remains, inadequate management (loss of fire regime; frequent mowing prior to seed set) has threatened the species. There are about 222 remaining occurrences and the species' overall range has shrunk dramatically. It is thought to have disappeared entirely from Wisconsin and Indiana.
Date Listed: 09/01/1988
Lead Region: Great Lakes-Big Rivers Region (Region 3)
Listing status: T
For most current information and documents related to the conservation status and management of Asclepias meadii, see its USFWS Species Profile
National NatureServe Conservation Status
Rounded National Status Rank: N2 - Imperiled
Global Short Term Trend: Decline of 30-50%
Comments: Declining due to habitat destruction and effects of fragmentation.
Degree of Threat: Very high
Comments: Asclepias meadii is threatened due to a number of factors including loss of habitat due to urbanization and agricultural land conversion, loss of pollinators (Betz 1975), pesticide application or drift from adjacent land, and a lack of adequate prairie management.
Loss of habitat and modification appears to be the primary cause of decline within A. meadii (Chaplin et al. 1990). Numerous historic sites have been destroyed through plowing and land conversion throughout its range (Freeman 1988, McGregor 1983, Kurz and Bowles 1981). Insufficient or inappropriate prairie management may lead to a gradual depletion of A. meadii plants through invasion of woody plants.
There are a number of specific threats to Illinois populations. A railroad right-of-way prairie is threatened by bank erosion, lack of fire, use of herbicides and plowing by railroad maintenance crews. Sand barren sites in the state are threatened by woody species encroachment, lack of fire management, and trampling by hikers (Kurz and Bowles 1981).
Long-term summer mowing of prairie land has likely had a negative effect on A. meadii by eliminating the reproductive output of plants (Chaplin et al. 1990). Mowing of prairies usually occurs in late June and early July (Freeman 1988, Brooks 1983) when fruits are present but immature (Chaplin et al. 1990).
Habitat fragmentation has resulted in the few remaining populations being separated by long distances, even in states like Kansas where populations are most numerous (Freeman 1988). This action has potentially led to reduced population viability through low levels of cross-pollination, as described in other members of the genus (Shannon and Wyatt 1986, Kephart 1981). Low numbers within a given population may result in decreased visitation rates by pollinators (Betz and Hohn 1981).
Plants are apparently susceptible to insect and fungal attack. A species of Curculionid and Cerambycid beetle has been shown to cause plant damage in both the larval and adult phases (Betz and Hohn 1978). Aphids may also be a potential problem in plants (Betz 1978), while seedlings are apparently very susceptible to damping-off (McGregor pers. comm., Betz pers. comm.). Chaplin (in litt.) has reported that insects are quite destructive on entire plants and the maturing seed pods.
Restoration Potential: Although there exists a strong need to enhance existing A. meadii populations through restoration activities, the recovery potential of A. meadii is not entirely known. Use of artificial propagation and transplantation techniques may be necessary to restore populations.
Marlin Bowles of the Morton Arboretum has been working on artificial crossing and propagation techniques involving A. meadii. Attempts at hand-pollination between plants at two Saline County, Illinois, sites proved unsuccessful this year (1990), but success was reached in cross-pollination attempts between Illinois and Missouri plants (Schwegman 1990b). An attempt at tissue culture with Saline County, Illinois, tissue also proved successful (Schwegman 1990b). Continued efforts along these lines may delineate problems in the breeding system at these sites and offer clues to make enhancement efforts feasible.
Preserve Selection and Design Considerations: Any attempt to protect an occurrence of A. meadii should take into account sufficient buffer to permit prairie management (prescribed burning), reduce the risk of potential threats (pesticide drift, etc.), and provide potential habitat for population expansion in the future. All areas which drain through an existing site should be placed under management in order to reduce problems associated with run-off (weed introduction into the site, etc.).
Management Requirements: The primary management need for A. meadii is the maintenance of adequate habitat for reproduction and population maintenance. Many of the extant sites are currently being hayed, while others are being grazed or under prescribed fire management regimes. Management through prescribed fire should be considered as the optimal management practice.
Population maintenance or enhancement through artificial propagation efforts should be considered at sites where numbers are currently insufficient to maintain population viability. There is evidence that A. meadii is not self-compatible in small populations and that the inability to outcross may either prevent pollination or cause abortion of follicles (Kephart 1981, Kurz and Bowles 1981). No individuals of A. meadii have successfully reproduced in Iowa in the past two years (1988 and 1989) (Perkins pers. comm.).
At present, establishment of a four-five year rotational, prescribed fire management regime at existing sites is considered to be the optimal management strategy. At sites that are mowed, implementation of an idle period every few years may benefit the population by allowing for potential seed production (McGregor pers. comm.). Although populations are able to maintain themselves over consecutive years of annual haying, asexual reproduction during those years is the only possible means of maintenance (Kephart (1981). Grazing of sites should not be considered as a viable management option, primarily due to the difficult nature in guaranteeing grazing regimes that will not negatively affect the occurrence.
Germination of plants in a greenhouse, then transplanted to extant sites, may be a means of increasing population levels (McGregor pers. comm.). In 1982, a land-owner in Kansas was persuaded to leave a strip of prairie unmowed. Seeds were collected and sent to Jack Walstrom (U.S. Soil Conservation Service, Salina, Kansas 67401) for propagation studies.
At sites where fire management and haying have not been implemented, encroachment of trees/shrubs may be taking place. Continued encroachment may lead to excessive shading of preferred habitat and declines in A. meadii population numbers. Prescribed fire coupled with manual removal of woody vegetation should be considered at such sites.
Management Programs: The Missouri Field Office of The Nature Conservancy is in the process of devising a management plan for the species at a newly acquired site (Ladd pers. comm.). Contact: Doug Ladd, Missouri Land Steward, The Nature Conservancy, Missouri Field Office, 2800 S. Brentwood Blvd., St. Louis, MO 63144. Telephone No. (314) 968-1105.
Although no management is currently being conducted specifically for Mead's milkweed on public prairies in Missouri, a management plan is scheduled to be written in 1990. Currently, prairies on which the milkweed occurs are being managed on a three-year rotation consisting of haying, resting, and burning. Contact: Tim Smith, Botanist, Missouri Natural Heritage Inventory, P.O. Box 180, Jefferson City, MO 65102-0180. Telephone No. (314) 751-4115.
Rockefeller Prairie in northeastern Kansas, which supports a large A. meadii population, is being managed through a prescribed burning and mowing regime. This is the only public-owned Mead's milkweed site in the state. Contact: Dean Kettle, Assoc. Director, Kansas Ecological Reserves, Foley Hall, 2041 Constant Ave., West Campus, Lawrence, KS 66047-2906. Telephone No. (913) 864-3241.
Prescribed burning and tree/brush cutting on prairies containing A. meadii plants has been conducted at sites in Illinois in order to reduce invasion of woody plants and increase the quality of the habitat. Efforts to increase seed production through hand pollination are also being undertaken at these extant sites. Currently, A. meadii is responding to habitat improvement efforts, but has not responded to pollination efforts. Contact: John Schwegman, Botany Program Manager, Illinois Natural Heritage Division, Department of Conservation, 524 S. 2nd Street, Springfield, IL 62706. Telephone No. (127) 785-8774.
Monitoring Programs: The Iowa Field Office of The Nature Conservancy is currently monitoring the species in Iowa (Perkins pers. comm.). Plans are to have each population monitored on an annual basis. Locations of every plant, stem height, number of flowers, number of stems and pod production are recorded. Contact: Wayne Ostlie, The Nature Conservancy, Iowa Field Office, 431 E. Locust, Suite 200, Des Moines, IA 50309. Telephone No. (515) 244-5044.
The Kansas Natural Heritage Program is monitoring the large populations in the state and those in close proximity to Lawrence, as time permits. An attempt is being made to conduct annual counts. Contact: Craig Freeman, Kansas Natural Heritage Program, Kansas Biological Survey, 2041 Constant Ave., Lawrence, KS 66047-2906. Telephone No. (913) 864-3453.
The Illinois Department of Conservation is monitoring all populations within the state using a system that unites annual census and demographic data with information on climate, disturbances, management activities and other factors (Schwegman 1990a). For specific details related to monitoring of populations, see Schwegman (1990a) and Schwegman (1987). Contact: John Schwegman, Botany Program Manager, Illinois Natural Heritage Division, Department of Conservation, 524 S. 2nd Street, Springfield, IL 62706. Telephone No. (217) 785-8774.
Extant Missouri populations are being monitored. Contact: Tim Smith, Botanist, Missouri Natural Heritage Inventory, Department of Conservation, P.O. Box 180, Jefferson City, MO 65102. Telephone No. (314) 751-4115.
Management Research Programs: A survey to locate additional populations of A. meadii within the state of Missouri was undertaken in 1989. According to Thurman (pers. comm.), 15 additional populations were found. Forty-three extant occurrences are now known within the state. Contact: Tim Smith, Missouri Natural Heritage Inventory, Missouri Department of Conservation, P.O. Box 180, Jefferson City, MO 65102. Telephone No. (314) 751-4115.
The Morton Arboretum is working on germination and propagation requirements of A. meadii seeds, as well as possible tissue culture techniques. Contact: Marlin Bowles, The Morton Arboretum, Route 53, Lisle, IL 60532. Telephone No. (312) 719-2422.
Management Research Needs: Research is needed to determine the response of A. meadii to prairie management such as burning, haying or grazing. It is already known that long-term haying practices will ultimately affect reproductive success. Also, prescribed fire management appears to be having beneficial impacts on A. meadii. In such instances, however, precise impacts related to the extent of each activity is not completely known.
Substantial research is needed on pollinator identification, pollinator life history, and pollen flow within and between populations. Such research is a primary requirement in order to initiate and plan appropriate management efforts (Ladd pers. comm.). Inappropriate management plans may lead to an unplanned destruction of pollinators or other detrimental acts.
Ladd (pers. comm.) stated that information is desperately needed concerning the recruitment and life history of Asclepias meadii. Research along this line will be beneficial in order to aid artificial propagation and restoration efforts now planned or currently underway.
An effort to determine the genetic variability within and among all A. meadii populations should be conducted as an accurate estimate of population size. Mowing may artificially heighten the numbers of ramets produced by a given plant, as has been noted for other species of milkweed such as Asclepias syriaca (Freeman pers. comm.). Consequently, ramet number is not an adequate item upon which to determine population size. Given equal ramet numbers, an undisturbed site that is managed through prescribed burns will likely possess higher numbers of individuals (and be of higher quality) than a site that is annually mowed.
Additional survey work for additional populations should be conducted where previous efforts have not been exhaustive. Research related to population reproduction at extant sites is also a need.
Biological Research Needs: Research needs to determine the response of A. meadii to prairie management options such as burning, haying or grazing; pollinator identification, pollinator life history, and pollen flow within and between populations; recruitment and life history of Asclepias meadii; genetic variability within and among all populations.
Relevance to Humans and Ecosystems
Stewardship Overview: Monitoring needs include the tracking of the status of A. meadii populations with respect to current management activities. Monitoring of individuals, reproductive success, vigor and habitat should be initiated. Research needs to determine the response of A. meadii to prairie management such as burning, haying or grazing. Substantial research is needed on pollinator identification, pollinator life history, pollen flow within and between populations of A. meadii, recruitment and life history. Additional survey work is also a need. The primary management need for A. meadii is the maintenance of adequate habitat for reproduction and population maintenance. Population maintenance or enhancement through artificial propagation efforts should be considered at sites where numbers are currently insufficient to maintain population viability.
Asclepias meadii is a rare species of milkweed known by the common name Mead's milkweed. It is native to the American Midwest, where it was probably once quite widespread in the tallgrass prairie. Today much of the Midwest has been fragmented and claimed for agriculture, and the remaining prairie habitat is degraded.
The plant is a federally listed threatened species due to this destruction of its habitat. Factors contributing to its rarity include mowing and plowing, erosion, loss of a natural prairie fire regime, pesticides directly applied or drifting from nearby agricultural operations, invasive plant species, trampling by hikers, loss of native insect pollinators, and predation by a number of insect species.
The only naturally-occurring populations of the plant are located in Missouri and Illinois, and populations have been reintroduced to Indiana and Wisconsin, where the plant had been extirpated. There are also some populations in Kansas and Iowa, but few of these may last, especially in Kansas, where they occur on private hay fields that are mowed frequently.
This is a rhizomatous perennial herb with a waxy erect stem growing up to about 40 centimeters tall. Blue-green, herringbone-patterned leaves occur in opposite pairs about the stem. The lance-shaped blades are smooth and sometimes wavy along the edges, and measure up to 8 centimeters long. The inflorescence is a nodding umbel of 6 to 23 fragrant flowers. Each flower has five petals up to a centimeter long which are green or purple-tinged when new and grow paler as they age. Behind them are five reflexed sepals. The flowers are nectar-rich and are pollinated by digger bees (Anthophora spp.), bumblebees (Bombus spp.), and other bees. The fruit is a follicle up to 8 centimeters long containing hairy seeds. The species is long-lived, taking at least four years to reach sexual maturity and living for several decades, possibly over a century.
The species often reproduces vegetatively by sprouting more stems from its rhizome. It also sometimes reproduces sexually by producing seed. A reduction in genetic diversity is a threat to the species, because human activity and other processes have favored vegetative reproduction, a cloning of the plants that does not remix genes. Mowing chops off the flowers or immature fruits, preventing seed production. Fragmentation of the habitat reduces the number of nearby plants that can trade pollen and the likelihood of visits from common pollinating insects.
The plant is adapted to occasional prairie fire, and the suppression of such fires is detrimental.  Fire may have a number of beneficial fire ecology effects on the plant, including increases in leaf and flower production and in genetic diversity. 
Insect pests that eat the plant include the milkweed beetles Tetraopes femoratus and Tetraopes tetraophthalamus and the milkweed weevils Rhyssematus annectans and Rhyssematus lineaticollis. This plant, like many other milkweeds, hosts the Monarch butterfly (Danaus plexippus).
- The Nature Conservancy
- Center for Plant Conservation
- Betz, R. F. (1989). Ecology of Mead's milkweed (Asclepias meadii) Torrey. in Proceedings of the 11th North American Prairie Conference; 1989; University of Nebraska, Lincoln. p 187-191.
- Grman, E. L. and H. M. Alexander. (2005). Factors limiting fruit production in Asclepias meadii in northeastern Kansas. American Midland Naturalist 153:2 245.
- USFWS. Determination of threatened status for Asclepias meadii (Mead's milkweed). Federal Register September 1, 1988.
- Assessment of the reintroduction potential of five federally threatened and endangered plant species at Midewin National Tallgrass Prairie, Table 3-2. USFS 1998.
Names and Taxonomy
Comments: A distinct species.