|Listed||October 12, 1984|
|Description||Shrub or small tree with round leaves and clusters of showy white flowers.|
|Habitat||Crevices in limestone cliffs beside streams.|
|Threats||Livestock grazing, erosion.|
Texas snowbells, Styrax texanus, are a smooth-barked shrub or small tree ranging in height from 5-13 ft (1.5-4 m). Leaves are nearly round, up to 3 in (8 cm) in diameter, with untoothed margins. Smooth and shiny green above, the leaves are silvery beneath from a dense covering of short, silky hairs. Showy white flowers appear in late April and early May in clusters of three to five.
Texas snowbells grow in crevices of streamside limestone cliffs on the Edwards Plateau and in the eastern Trans-Pecos Basin. Cliff-side sites are not necessarily the plant's preferred habitat but may represent a refuge from livestock that graze the canyon floors. Surrounding vegetation consists of juniper-oak savannah or creosote-bush scrub. Associated plants are Texas oak, juniper, ash, barberry, creosote, and woolly bumelia.
This plant is endemic to Edwards, Real, and Val Verde counties in south-central Texas, but researchers have discovered few Texas snowbells seedlings or saplings in the wild, indicating almost complete reproductive failure. About 40 shrubs were known to exist at six localities in the wild in 1987. This figure included plants reported from along Polecat, Cedar, and Little Hackberry creeks (Edwards County), and from the East Prong of the Neuces River (Real County). Plants also were reported, but not confirmed, on the Horace Faucett Ranch in Val Verde County. A population was recently transplanted at a site in Hill County from cultivated stock.
Low numbers and a near-failure of natural reproduction make known populations particularly vulnerable to extinction. The absence of seedlings and young plants is almost certainly due to browsing cattle, deer, and imported sheep that are pervasive in the region. Stream bank erosion, worsened by flash-flooding and livestock grazing, also poses a significant threat to surviving wild plants.
Conservation and Recovery
In 1985, the Fish and Wildlife Service (FWS) entered into agreements with two landowners, who have offered to manage their properties to conserve Texas snowbells. Also in 1985, the staff of the San Antonio Botanical Garden began collecting seed from wild plants in order to cultivate the species as part of the garden's National Collection. After experimenting with various techniques of seed germination, staff botanists achieved an 85 percent germination rate. This success at once improved Texas snowbells' chances for survival.
In spring 1987, greenhouse-raised seedlings were transplanted to a site in Hill County west of San Antonio. The goal of this joint venture of the FWS, the San Antonio Botanical Gardens, Southwest Texas Junior College, and the Texas Natural Heritage Program is to triple the number of wild plants. The transplanted population is on private land, but the project enjoys the enthusiastic cooperation of the landowner.
Mahler, W. F. 1981. "Status Report: Styrax texana."Office of Endangered Species, Albuquerque.
U.S. Fish and Wildlife Service. 1984. "Determination of Texas snowbells, Styrax texana, to Be an Endangered Species." Federal Register 49: 40038.
U.S. Fish and Wildlife Service. 1987. "Texas Snow-bells (Styrax texana ) Recovery Plan." U.S. Fish and Wildlife Service, Albuquerque.