Mead's Milkweed

Asclepias meadii

Description

Mead's milkweed, Asclepias meadii, is a perennial herb that puts up a single, unbranched stalk, 8-16 in (20-40 cm) tall. The stalk is hairless but has a white sheen caused by a waxy covering. The broad, ovate leaves, up to 3 in (7.5 cm) long, are opposite. Six to 15 cream-colored flowers are grouped into a flat-topped cluster (umbel) at the ends of the stems. Blooming is in late May and early June. Fruit pods appear in June and gradually grow to full maturity in October. Mature pods eventually split and disperse hundreds of hairy seeds that are carried by the wind.

Habitat

Mead's milkweed is found on virgin prairie as a solitary plant or in small colonies. Populations, rarely numbering more than 20 plants, are found on unplowed bluestem prairie in Missouri consisting of deep, silty loams. It is found in similar habitat in the other states of its range.

Distribution

The species was formerly widespread over much of the native tallgrass prairie region of the Midwest, which included portions of Illinois, Indiana, Iowa, Kansas, Missouri, and Wisconsin. Mead's milkweed is thought to have disappeared from Indiana and Wisconsin.

When the species was federally listed, 81 sites were known from 23 counties within Illinois, Iowa, Kansas, and Missouri. Although seemingly widespread, the number of plants at each site are few, and the overall range has shrunk dramatically. The plant's former range of seven Illinois counties has now decreased to three sites in Ford and Saline Counties. Formerly found in 11 Missouri counties, it now occurs in seven, mainly in the southwestern quadrant of the state (Barton, Benton, Dade, Pettis, Polk, St. Clair, and Vernon Counties). Two of the largest populations, numbering more than 800 plants at each site (1988) are near Lawrence, Kansas. Once known from five Iowa counties, only two small populations remain in Adair and Warren Counties. A 1991 theft of an entire population of six individuals in Shawnee National Forest in Illinois offered renewed evidence of the dangers of publicizing, or even acknowledging, the wilderness locations of endangered species. Following the theft, the known populations were reduced to 80.

Fortunately, in the spring of 1996, two new populations of Mead's milkweed were discovered on rhyolite glades in southcentral Missouri. One small population is on Wildcat Mountain in Taum Sauk State Park. A much larger population was found on Profit Mountain within the Missouri Department of Conservation's Ketcherside Mountain Conservation Area.

Threats

The type of virgin prairie preferred by Mead's milkweed and other Midwestern endemics has become increasingly rare in recent years. Most deep-loamed soils have been farmed at one time or another. Hay meadows have gradually been converted to grain crops. Remaining hay meadows are mowed two or three times a year before stray milkweed plants have a chance to set seed.

If there was any question about the dangers of illegal collecting, they were answered, bitterly, in June, 1991, when an entire population of six plants was snatched from a remote location of the Shawnee National Forest in Illinois. Concentrated within a half-acre site, the plants were either carefully dug up or cut off with a razor blade. Monitoring the population weekly, botanists at the National Forest contacted the Fish and Wildlife Service's Division of Law Enforcement in the Twin Cities within two hours of discovering that the plants were gone. The population consisted of both wild specimens and young, introduced stock recently planted in a joint effort to reestablish Mead's milkweed in its historic range. One of only six places where the threatened species was known to exist east of the Mississippi River, Shawnee National Forest was considered the premier site for reintroducing the plant into its native habitat.

Currently, remnants of virgin prairie are succumbing to urban commercial and residential expansion. Several of the largest populations near Lawrence, Kansas are in areas that are virtually certain to be developed for housing within the next few years. None of the known populations are considered secure.

Conservation and Recovery

The key to the survival of the Mead's milkweed is the protection of the remnants of its critical prairie habitat. Some habitats are being conserved, including areas in Taum Sauk State Park and Ketcherside Mountain Conservation Area in Missouri, and in the Shawnee National Forest in Illinois. However, most critical habitats are on private land and are potentially threatened by various human activities, especially agricultural conversion. These habitats should be protected by acquiring the land and designating ecological reserves, or by negotiating conservation easements with the owners. The populations of the Mead's milkweed should be monitored, and research undertaken into its biology, habitat needs, and beneficial management practices. The rare plant should be propagated in captivity to provide stock for out-planting to increase the size of existing populations and to establish new ones in suitable prairie habitat.

Contact

U.S. Fish and Wildlife Service
Division of Endangered Species
Administration Office
Federal Building
1 Federal Drive
Fort Snelling, Minnesota 55111-4056
Telephone: (612) 713-5360
Fax: (612) 713-5292

References

Alverson, W. S. 1981. "Status Report on Asclepias meadii." Wisconsin Department of Natural Resources, Madison.

Bacone, J. A., T. J. Crovello and L. A. Hauser. 1981."Status Report on Asclepias meadii." Indiana Department of Conservation, Indianapolis.

Betz, R. F. and J. E. Hohn. 1978. "Status Report forAsclepias meadii." Contract Report to U.S. Fish and Wildlife Service, Twin Cities, Minnesota.