Texas wild-rice is only known from the upper two miles of the San Marcos River in Hays County, Texas.
Texas wild-rice is a clumping perennial grass that roots underwater in riverbeds. The 1-2 m long stems bend, flowing parallel to the current, but the upper stem can bend back upward, above the water surface. The linear leaves are narrow (usually 3-25 mm wide), to 200 cm long, and a prominent vein running down the middle of the blade. Male and female flowers occur separately on side branches of a 16-31 cm long flowering stalk. The male flowers dangle off the lower side branches of the flowering stalk, while the female flowers are produced on the stiffly erect upper side branches. As is typical of grasses, flowers are quite small (6.5-12.5 mm long, 1.2-2 mm wide) and inconspicuous. Male flowers bear pollen, are oblong to egg-shaped, and are slightly pointed at both ends. Female flowers produce seed, and the flowers are topped with a very thin, 9-35 mm long bristle. Texas wild-rice seeds are cylindrical, 4.3-7.6 mm long, 1-1.5 mm wide, and either black, brown or greenish.
Stems of giant cutgrass (Zizaniopsis miliacea) usually emerge from the water and grow to 4 m long. The male and female flowers occur on the same branches, with the female flowers closer to the stem’s tip than the male flowers. Eel grass (Vallisneria spiralis) and Illinois pondweed (Potamogeton illinoensis) both occur with Texas wild-rice and appear similar, but neither have the strong vein which runs down the middle of the Texas wild-rice blade.
Texas wild-rice grows in gravelly or coarse sandy soils in clear, cool, fast-flowing waters of spring-fed rivers.
Life Cycle Events
Flowering occurs from spring to summer, but flowering has been observed throughout the year.
Texas wild-rice can be identified year-round.
- Rare Plants of Texas
- U.S. Fish and Wildlife Service
- Center for Plant Conservation
- Grass Manual on the Web
- Poole, J.M. 2002. Map historical distribution of Texas wildrice (Zizania texana) 1989 to 1999. Section 6 final report. Austin: Texas Parks & Wildlife Department.
- Poole, J.M. and D.E. Bowles. 1999. Habitat characterization of Texas wild-rice (Zizania texana Hitchcock), an endangered aquatic macrophyte from the San Marcos River. Aquatic Conservation. 9: 291-302.
- Poole, J.M. and G.K. Janssen. 1997. Managing and monitoring rare and endangered plants on highway right-of-ways in Texas. Section 6 final report. Austin: Texas Parks & Wildlife Department.
- Power, P. 2001. Continued maintenance, reintroduction and research on Texas wildrice (Zizania texana). Section 6 final report. Austin: Texas Parks & Wildlife Department.