Canby's Dropwort

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Canby's Dropwort

Oxypolis canbyi

Status	Endangered
Listed	February 25, 1986
Family	Umbelliferae (Apiaceae)
Description	Perennial plant with quill-like leaves and white flowers.
Habitat	Coastal plain wetlands.
Threats	Loss of wetlands.
Range	Delaware, Georgia, Maryland, North Carolina, South Carolina

Description

Canby's dropwort, Oxypolis canbyi, is a perennial plant with a faint dill fragrance. Stems grow up to 3.9 ft (1.2 m) tall and bear slender quill-like leaves. Flowers are displayed in compound flat-topped clusters (umbels) from May through early August. The small, white five-petaled flowers have pale green sepals that are sometimes tinged with red. Canby's dropwort has a strong colonizing habit and spreads vigorously by a pale, fleshy rhizome.

Habitat

Canby's dropwort inhabits a variety of moist habitats, such as swamps, shallow pineland ponds, and wet pine savannahs. Many of the freshwater wetlands once inhabited by Canby's dropwort have been drained and converted to lowland pastures, pine plantations, and soybean fields.

Distribution

This species was once relatively common throughout much of the coastal plain wetlands of the mid-Atlantic region. It was found as far north as Delaware and as far south as Georgia during the 1890s.

Canby's dropwort is found at ten sites in Georgia, North Carolina, South Carolina, and Maryland.

When listed in 1986, three populations were known from Burke, Lee, and Sumter counties of Georgia; the majority of plants were located on private lands. A single population was discovered in Scotland County, North Carolina, a site that is owned in part by The Nature Conservancy. There are no current population estimates for these sites.

Five known populations occur in South Carolina: a vigorous colony of about 500 stems in Colleton County; a second population of 600 stems on private land in Bamberg County; and three smaller populations in Richland and Barnwell counties that were discovered in 1984. The Colleton County site is owned by the Nature Conservancy, and efforts to acquire land at the Bamberg site are underway.

In 1982, a single population of stems was discovered near the site of a proposed water project in the Chester River watershed (Queen Annes County), Maryland. Previously, the species had not been found in the state. This site was acquired by the Maryland Chapter of The Nature Conservancy in early 1984. Still, the state's sole population declined from more than 200 plants in the mid-1980s to only three plants in 1989, likely because of the record droughts in 1987 and 1988. In an attempt to save the Maryland genotypes, two of the three remaining Endangered plants were removed from the wild in October 1989 and transferred to the North Carolina Botanical Gardens. In 1990, both plants flowered and set seed in late summer. Federal and State personnel have joined in a cooperative effort to minimize any adverse impacts to the plants concerning the Upper Chester River Watershed Channelization Project.

Threats

Canby's dropwort habitat along the East Coast has steadily disappeared. Suburban development has caused groundwater tables to fall in many areas, and lower water tables allow other plants to become established, crowding out the dropwort. Road construction has filled or drained many lower-lying, swampy areas. Habitat loss continues and poses a threat to all populations. Even protected sites can be eliminated when drainage of adjacent land lowers the water table. Several populations were lost as shallow ponds and wetlands were drained for conversion to lowland pastures, pine plantations, soybean fields, and other agricultural uses. Another, less aggressive threat to the species is the black swallowtail butterfly; the dropwort seems to be a favorite food for the butterfly's larvae, and several sites have been subject to predation.

Conservation and Recovery

The Recovery Plan for this species will examine options to preserve remaining habitat and to reintroduce the plant into suitable tracts of habitat within its former range. The Nature Conservancy continues to play a leading role in conserving this plant. The only known Federal action that might affect the O. canbyi or its habitat is a planned Soil Conservation Service (SCS) channelization project for the Upper Chester River watershed. Maryland's only known population of this species is within the project area.