The following Participating Institutions are custodians for this species in the CPC National Collection:
The Lady Bird Johnson Wildflower Center
San Antonio Botanical Garden
The conservation of Zizania texana is fully sponsored.
Cindy Barrett contributed to this Plant Profile.
Texas wild rice is an aquatic herbaceous perennial which can be found growing only in the cool, clear waters of the San Marcos River in Texas. This species was so abundant in the 1930's that the local irrigation company considered it difficult to keep this plant from clogging its ditches. In striking contrast, this species is now listed as federally endangered (USFWS 1978), with only a few populations known in the wild. A main cause of this decline is the fact that water has been pumped out of the Edwards Aquifer to supply water for agriculture, industry, and human use. This directly effects the spring flow of the San Marcos River, which this wild rice depends upon. Lowering of the river water levels is a major threat to the survival of this species.
Texas wild rice is related to commercially grown wild-rice, and therefore a potentially invaluable resource of hardy genetic stock.
Distribution & Occurrence
This aquatic grass is found in the San Marcos River, forming large clones or masses of clones firmly rooted in shallow gravel beds near the middle of the river. This plant is adapted to and requires fast-flowing, high quality water at a constant year-round temperature. Critical habitat was designated in 1980. (WWF 1990; USFWS 1980)
| 140 clumps in one unprotected population
100 plants introduced at Spring Lake, 90 surviving and doing well, starting inflorescence development
population maintained on the Southwest Texas State University campus in an outdoor cement raceway
Current distribution of wild rice extends from the uppermost part of the San Marcos River just below Spring Lake dam and throughout the critical habitat down to an area slightly below the wastewater treatment plant, except for the river portion between the Rio Vista railroad bridge and the dam above Cheatham Street.
Conservation, Ecology & Research
Pollution from vegetation management
Stream modification by damming
Recreation--including swimming and boating in and around the populations
Nutria (aquatic rodents) eating stalks
Seed dispersal and seedling recruitment
Public education campaign
Restore/maintain the historic flow of the San Marcos River
Gould, F.W. 1975. The grasses of Texas. College Station: Texas A & M Univ. Press. 653p.
Silveus, W.A. 1933. Texas grasses. San Antonio, TX: Privately published. 782p.