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PDF of the report page
Texas Wild Rice
(Zizania texana)
Status:
Endangered since 1978
Range:
A two-mile segment
of the upper San Marcos River
in central Texas
Population:
A two-mile segment
of the upper San Marcos River
in central Texas
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The San Marcos River’s headwaters are the San Marcos Springs, which rise from the Edwards Aquifer in central Texas. The San Marcos spring field is one of the largest in the United States, and water has traditionally been so plentiful that the river has never run dry in recorded history. It is cool, clear, and swift-flowing, running through the City of San Marcos and then joining the Blanco River about four miles below the springs.
Texas wild rice is an aquatic herbaceous perennial grass found only in the San Marcos River. The plants root firmly in the gravelly bottom, and have bright green, linear leaves up to six feet long that live completely immersed and undulating in the swiftly flowing water. It produces narrow flower stalks that emerge above the water.
Flowering typically occurs in the spring and fall, although it may occur throughout the year in warm weather. This wild rice is well adapted to high quality water at a near-constant temperature. Once abundant, the species is now so rare that it is found only in a short stretch of the upper San Marcos River.
Water in the Balance
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What You Can Do
The Center for Plant Conservation has helped save Texas wild rice through funding, research, and collaboration with U.S. Department of Agriculture to establish a seed bank. In addition, the US Fish and Wildlife Service, the Texas Parks and Wildlife Department, the City of San Marcos, Texas State University, The Edwards Aquifer Authority, the San Antonio Water System, various municipalities, agricultural interests, and other waterinterested stakeholders have implemented different tactics to protect the plant, such as maintaining plants at fish hatcheries, conducting monitoring, research, and restoration projects, educating the public, keeping the river clean, and developing plans and methods to reduce water use during times of drought. Individuals should use the river responsibly by refraining from dumping automotive fluids, solvents, and aquarium fish and plants, and by supporting efforts to protect the water supply, to prevent urban runoff, and to implement reasonable recreation management plans.
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The plant’s deep, clear-water habitat has been in decline due to increasing agricultural, industrial, and residential demands. The Edwards Aquifer is the primary pumping source for millions of people and countless economic enterprises. Lowering the aquifer directly affects the spring flow, and consequently lowers the San Marcos River. Over most of Texas, landowners and companies can pump out massive amounts of water, even drying up wells under Texas’ “rule of capture.” However, the State has established the Edwards Aquifer Authority and a Barton Springs/Edwards Aquifer Conservation District to ensure that the aquifer can provide sufficient water for the river’s seven threatened and endangered species. Meanwhile, urbanization is leading to water pollution and an over-abundance of sedimentation due to urban and construction run-off. Other threats include invasive species, including non-native aquarium plants, and damage from recreational activities.
The San Marcos River system has recently been included in a federal Habitat Conservation Plan, and the State of Texas has declared the upper two miles of the river a State Scientific Area, which affords a degree of habitat protection. Ensuring optimum conditions for Texas wild rice benefits biodiversity and people, as businesses and municipalities are dependent on spring flows for recreational tourism dollars.
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