|Listed||January 13, 1981|
|Description||Erect, basally branched perennial herb with rough-haired stems and leaves; purple cup-like flowers.|
|Habitat||Alluvial sand deposits.|
|Threats||Sand mining, habitat disturbance, wind erosion.|
Texas poppy-mallow, Callirhoe scabriuscula, is an erect perennial herb, growing from a long, fleshy taproot. Stems typically branch at the base and average 36 in (90 cm) in height. Leaves and stems are covered with rough, star-shaped hairs. The flower, about 1.5 in (4 cm) across, is formed from five wine-purple petals held erect in a partially open cup with a dark maroon center ring. In the fall, the stalk dies off and the plant overwinters as a low rosette of three to eight leaves.
Flowers bloom from late April through late June, opening after sunrise and closing before sunset. Pollinated flowers close permanently, while unpollinated flowers continue to open for about a week. Pollinators include insects such as bees and moths that shelter inside flowers during the night.
Six of seven species of Callirhoe are found in Texas. Texas poppy-mallow is differentiated from its relatives by its larger leaves and by the color of the flowers. Flowers are white in most other species.
Texas poppy-mallow grows in deep, alluvial sands within the Rolling Plains vegetation zone of south central Texas along the banks of the Colorado River. These fine sands have a high water intake rate with little runoff, and dune formation is common. This type of habitat is unusual for the region and was created when sands were deposited along the river and then blown into dunes above the floodplain.
Associated plant species are mostly sand-adapted, and many are not found in adjacent habitats. These include bull nettle, Indian blanket, yellow woolly-white, eastern sensitive briar, trailing wild-bean, and prairie spiderwort.
The Texas poppy-mallow is endemic to a narrow strip of habitat along the Colorado River from Mitchell County downstream to south-central Runnels County (the area is generally situated halfway between Abilene and San Angelo, Texas). Similar habitat occurs elsewhere along the Colorado River and also along the Red River, and these sites are being surveyed for possible plant populations.
A site several miles southwest of Ballinger in Runnels County, is apparently the population center for the species. This population is scattered across 395 acres (160 hectares), distributed in localized clusters. Other populations occur upstream in Coke and Mitchell counties. A few plants spill over onto state-owned land along major roads, but the bulk of the population grows on private property. In 1979 the total number of plants in 16 small populations was estimated at 48,000, but a survey in 1983 revealed that sand mining had destroyed much of the habitat and eliminated a large number of plants. All known populations have declined in numbers.
The restricted habitat of the Texas poppy-mallow has been further reduced by commercial sand mining and by livestock grazing. The dunes are susceptible to wind erosion once the fragile ground cover has been graded, browsed or trampled.
There are numerous other threats as well, including agricultural chemicals, residential development, and maintenance of a major highway, frontage roads, railroad, and transmission lines. Herbicides are commonly used by private landowners and the railroad maintenance crew. Insecticides are used by private landowners, and crop dusters regularly fly over the habitat. The highway department mows the roadside, and collectors take plants for their gardens.
Conservation and Recovery
Between 1979 and 1983, populations of Texas poppy-mallow declined dramatically in size and vigor due to habitat destruction. In 1987 the Texas Nature Conservancy entered into an agreement with the U.S. Fish and Wildlife Service to cooperate in the recovery of the Texas poppy-mallow by maintaining, then expanding, existing populations. An initial goal of the agreement was to make landowners aware of the significance of the plant and to seek their cooperation in preserving populations found on private property.
The Recovery Plan calls for an annual inspection of the populations, and regularly monitoring them. It recommends controlling sand mining activities and development, and erecting fences around populations for protection against collectors.
The plan also calls for monitoring population size, conducting ecological and life studies, studying seed viability and seed germination, and conducting searches for additional populations and potential habitat sites.
Amos, B. B. 1979. "Determination of Callirhoe scabriuscula Robins. as an Endangered Species." U.S. Fish and Wildlife Service, Albuquerque.
Gould, F. S. 1975. "Texas Plants, a Checklist and Ecological Summary." Texas Agricultural Experiment Station, College Station, Texas.
U.S. Fish and Wildlife Service. 1985. "Texas Poppy-mallow (Callirhoe scabriuscula ) Recovery Plan." U.S. Fish and Wildlife Service, Albuquerque.
U.S. Fish and Wildlife Service. 1987. "Endangered and Threatened Species of Texas and Oklahoma (with 1988 Addendum)." U.S. Fish and Wildlife Service, Albuquerque.