Zizania texana - A.S. Hitchc.
Texas Wild Rice
Other Common Names: Texas wildrice
Taxonomic Status: Accepted
Related ITIS Name(s): Zizania texana Hitchc. (TSN 41321)
Unique Identifier: ELEMENT_GLOBAL.2.155192
Element Code: PMPOA6J020
Informal Taxonomy: Plants, Vascular - Flowering Plants - Grass Family
Image 12045

Public Domain

 
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Monocotyledoneae Cyperales Poaceae Zizania
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Concept Reference
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Concept Reference: Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Concept Reference Code: B94KAR01HQUS
Name Used in Concept Reference: Zizania texana
Taxonomic Comments: A generally accepted species in a genus of about four species (two others widespread in North America, and another in Asia). Accepted by U.S. Fish and Wildlife Service (federal listing as endangered, 1978), Kartesz (1994 checklist and 1999 floristic synthesis), and Judziewicz et al. (checklist New World grasses, 2000). Described and named by Hitchcock in 1933. LEM 2Feb00.
Conservation Status
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NatureServe Status

Global Status: G1
Global Status Last Reviewed: 16Jan2002
Global Status Last Changed: 21Sep1989
Rounded Global Status: G1 - Critically Imperiled
Reasons: Endemic to the upper few km of the San Marcos River in south-central Texas, where it was locally abundant as recently as the the 1950s. It is now reduced to a precariously small population covering about 1200 square meters on an urbanized segment of the river. This remnant population rarely flowers or produces seed in the wild. The decline of this grass, which is narrowly adapted to high quality, aquifer-fed waters, is the result of drastic draw-downs in the aquifer level to support human population growth in the area, combined with past dredging and vegetation removal, damming, increased siltation and sewage loads, trampling and removal by recreationists, and herbivory by native and introduced waterfowl and by the non-native nutria. Efforts to establish new populations off the San Marcos River using cultivated plants have not been successful.
Nation: United States
National Status: N1

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Texas (S1)

Other Statuses

U.S. Endangered Species Act (USESA): LE: Listed endangered (26Apr1978)
U.S. Fish & Wildlife Service Lead Region: R2 - Southwest

NatureServe Global Conservation Status Factors

Range Extent Comments: Known only from one area in Texas in the headwaters of the San Marcos River; these plants were variously identified as Zizania aquatica or Z. palustris before being recognized as a distinct species by W. A. Silveus in 1932 (cf. Terrell et al., 1978) and subsequently described and named by Hitchcock in 1933.

Area of Occupancy: 1-5 4-km2 grid cells
Area of Occupancy Comments: Extant in only a small area of one river, about 1.5 miles (2.4 km) in length and 5-15 m wide, with actual area of occupancy estimated at 240 square meters by one technique in 1975 and 1131 square meters by another technique in 1976 (Terrell et al., 1978).

Number of Occurrences: 1 - 5
Number of Occurrences Comments: Known only from the one site in the headwaters of the San Marcos River at San Marcos, Texas.

Population Size Comments: Less than 500 individuals.

Number of Occurrences with Good Viability/Integrity: Very few (1-3)
Viability/Integrity Comments: The one known occurrence remain capable of persisting with continued management and threat abatement.

Overall Threat Impact Comments: Extremely limited distribution; one catastrophic event could eliminate entire species. While some historical threats are no longer significant, the species is in an urban area heavily used recreationally, and depends on continued flow of clean, cool spring water from the Edwards Aquifer.

Long-term Trend: Decline of >90%
Long-term Trend Comments: By 1967, this species had greatly declined in numbers and distribution extent along the upper San Marcos river since the 1930's (Emery, 1967), and continued to decline to a lesser degree, despite reduction in some threats, in the following decade (Emery, 1977; Terrell et al., 1978).

Intrinsic Vulnerability Comments: Persists vegetatively but rarely produces seed under current conditions.

Environmental Specificity: Very narrow. Specialist or community with key requirements scarce.
Environmental Specificity Comments: Restricted to clear, cool, fast-flowing spring water (unusual in south-central Texas).

Other NatureServe Conservation Status Information

Distribution
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Global Range: Known only from one area in Texas in the headwaters of the San Marcos River; these plants were variously identified as Zizania aquatica or Z. palustris before being recognized as a distinct species by W. A. Silveus in 1932 (cf. Terrell et al., 1978) and subsequently described and named by Hitchcock in 1933.

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map

U.S. & Canada State/Province Distribution
United States TX

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
TX Hays (48209)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
12 San Marcos (12100203)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: An aquatic perennial grass with only a few leaves and the flowering stalk extending above the water surface, sometimes to a height of 1 m. Including the below-surface portion, the plants are often more than 2 m long, and the bright green leaves are typically seen trailed out to their full length by river currents. This species is a close relative of cultivated wild rice, which grows only in much cooler regions, far to the north.
Riverine Habitat(s): SPRING/SPRING BROOK
Habitat Comments: A clear, flowing waters of spring origin with a relatively constant year-round temperature of 21-25 degress C. The plants grow in gravelly, sandy to silty clays in relatively shallow water (<2 m deep).
Economic Attributes Not yet assessed
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Management Summary Not yet assessed
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Population/Occurrence Delineation Not yet assessed
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Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 12Mar1985
NatureServe Conservation Status Factors Author: Brown, B.A., rev. Poole/Maybury (1996), rev. L. Morse (2001, 2004)

Botanical data developed by NatureServe and its network of natural heritage programs (see Local Programs), The North Carolina Botanical Garden, and other contributors and cooperators (see Sources).

References
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  • Emery, W.H.P. 1967. The decline and threatened extinction of Texas wild rice (Zizania texana Hitchc.). Southwestern Naturalist 12(2): 189-205.

  • Emery, W.H.P. 1977. Current status of Texas wild rice (Zizania texana Hitchc.). Southwestern Naturalist 22(3): 389-406.

  • Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.

  • Lowe, D.W., J.R. Matthews, and C.J. Moseley, eds. 1990. The official World Wildlife Fund guide to endangered species of North America. Beacham Publishing, Washington, D.C. 1180 pp.

  • Poole, Jackie M., W. R. Carr, D. M. Price, and J. R. Singhurst. 2007. Rare plants of Texas. Texas A&M University Press, College Station. 640 pp.

  • Terrell, E.E., W.H.P. Emery, and H.E. Beaty. 1978. Observations on Zizania texana (Texas wildrice), an endangered species. Bull. Torrey Botanical Club 105(1) 50-57.

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