White Sedge

Carex albida

Description

Liberty Bailey described Carex albida (white sedge) in 1889 from a specimen collected by John Bigelow in 1854 on Santa Rosa Creek, Sonoma County, California. Specimens of the plant collected by John Howell and John Stacey in 1937 were described by Stacey that same year as C. sonomensis, but 20 years later Howell stated that the type specimen of C. albida had been misinterpreted by Stacey and others and that C. sonomensis is actually a synonym of C. albida. Howell's interpretation is still accepted.

Carex albida is a loosely tufted perennial herb in the sedge family (Cyperaceae). The stems are triangular, 1.3-2 ft (39-60 cm), erect, and longer than the leaves. The leaves are flat and 1-2 in (3-5 cm) wide with closed sheaths. The inflorescence consists of four to seven ovoid or obovoid to oblong spikelets 0.3-0.7 in (8-18 mm) long. The achenes (fruits) are three-sided when mature. The sacs (perigynia) surrounding the achenes are light green to yellow-green when mature and 0.1-0.2 in (3-4.5 mm) long. Several traits distinguish C. albida from other closely related sedges. Carex albida has inflorescences with staminate flowers above the pistillate flowers (especially on the terminal inflorescence), lateral spikelets, and leaves that are shorter than the stems and 0.1-0.2 in (3-5 mm) wide. Some individuals of Carex lemmonii resemble C. albida, but differ primarily in perigynia and fruit size.

Habitat

The white sedge grows in coastal marshes and sphagnum bogs.

Distribution

Carex albida was thought to be extinct but is now known from a single population discovered in 1987. This taxon was known historically from four other locations in Sonoma County, including the type locality on Santa Rosa Creek and three additional populations in two marshes. The marsh containing C. albida at the Santa Rosa Creek site was destroyed in the 1960s by channelization and other alterations to Santa Rosa Creek. A second marsh has been used for cannery waste disposal since 1971, causing the probable loss of the population. At the third marsh, one of the two historical populations has not been seen since 1951, while access to the other population, not confirmed since 1976, has been denied by the landowner. This marsh has become drier in recent years because the addition of wells and other construction has altered the marsh hydrology, and it likely no longer supports the species. The only extant population of C. albida is found on private property in Sonoma County in a sphagnum bog that is between 150 and 200 ft (45 and 60 m) in elevation. The population contains about 1,000 plants in an area less than 300 sq m (3,300 sq ft) at a location 150 ft (46 m) from the state highway.

Threats

The single Carex albida population is threatened by potential alteration to site hydrology caused by wetland drainage or fill, invasive plant species that would be competitively favored by drier conditions, potential disturbance from a wastewater treatment plant, changes in land management by the owner, and potential disturbance from repair or alteration of a nearby state highway.

A wastewater treatment plant has been built 330 yards (300 m) from the Carex albida population. This project, as originally proposed, would have exposed the taxon to adverse effects from the application of recycled wastewater and the temporary or permanent removal of wetlands, riparian vegetation, and special status plants and their habitats. The treatment plant is operating, but the use of recycled wastewater has not yet been implemented. If implemented, from 7,680 to 12,936 g (12,000 to 49,000 l) wastewater per year would be applied on approximately 35 to 60 acres (14 to 27 hectares) of land. Although the population of C. albida would not be directly affected, the application of this volume of wastewater could damage the habitat that supports the plant through modification of surface hydrology.

Draining the wetland would directly damage the species and would also encourage the spread of blackberries (Rubus spp.), which have become dominant in other parts of the marsh that have been drained.

Conservation and Recovery

The white sedge is only known to survive in a single population. Its only critical habitat is on private property and is potentially threatened by various human activities. Survival of the white sedge requires that this critical habitat be strictly protected. This could be done by acquiring the habitat and establishing an ecological reserve, or by negotiating a conservation easement with the landowner. The populations of the white sedge should be monitored, and research undertaken into its ecological needs. Searches should be made for additional populations, and new ones should be established in suitable habitat.

Contact

U.S. Fish and Wildlife Service
Sacramento Fish and Wildlife Office
Federal Building
2800 Cottage Way, Room W-2605
Sacramento, California 95825-1846
Telephone: (916) 414-6600
Fax: (916) 460-4619

Reference

U.S. Fish and Wildlife Service. 22 October 1997. "Endangered and Threatened Wildlife and Plants; Determination of Endangered Status for Nine Plants From the Grasslands or Mesic Areas of the Central Coast of California." Federal Register 62 (204): 54791-54808.