Little Aguja Creek Pondweed

Potamogeton clystocarpus

Description

Potamogeton clystocarpus (Little Aguja Creek pondweed) is a slender, aquatic plant. Its branched stem usually has two small translucent glands at the stem nodes. The submerged, translucent light green leaves are linear, about 2-4.5 in (5-12 cm) long. The flower spikes, which have two or three whorls of flowers, emerge from the water, but submerge when fruiting. The fruits, which have distinctive warty protuberances at the base, develop from early May to October.

Habitat

This species is limited to a few scattered pools of an intermittent stream that flows through Little Aguja Canyon in the Davis Mountains (Jeff Davis County) of west Texas. The stream flows mostly underground through gravel bars. Plants root in the pools in igneous derived alluvium. Although there are many pools in the canyon streambed, this pondweed species is found in only two.

Distribution

This pondweed was first collected in 1931. Thorough surveys of the area, conducted during the 1980s, failed to discover other populations. Today, Little Aguja Creek pondweed is found only in two quiet pools of the Little Aguja Canyon streambed. The entire known species population occurs on a ranch owned by the Boy Scouts of America.

Threats

The main threat to this rare pondweed is the low number of known plants. During alternating periods of drought and flooding, plants are reduced to stem pieces and seeds, and the entire population must regenerate itself. Severe natural events may cause the population to fall below the level at which it can sustain itself. In addition, such low numbers make the species vulnerable to trampling by horses and wildlife and to any decline in water availability or quality. The landowner has been notified by the U.S. Fish and Wildlife Service (FWS) of the pondweed's presence and rarity.

Conservation and Recovery

The FWS published a Recovery Plan for the Little Aguja Creek pondweed in 1994. This rare plant is only known from a stretch of several miles of a single stream in Texas, and has not been seen there since severe flooding in 1991 and 1992. The intent of the recovery plan is to search for surviving populations of the Little Aguja Creek pondweed. If any are found, their habitat is to be protected and other necessary conservation actions designed and implemented.

Contact

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
P.O. Box 1306
Albuquerque, New Mexico 87103
Telephone: (505) 248-6911
Fax: (505) 248-6915
http://southwest.fws.gov/

References

Gould, F. W. 1975. "Texas Plants: A Checklist and Ecological Summary." Texas Agricultural Experiment Station, Texas A&M University, College Station, Texas.

Haynes, R. R. 1974. "A Revision of North AmericanPotamogeton Subsection Pusilli (Potamogetonaceae)" Rhodora. 76:624-626.

Rowell, C. M., Jr. 1983. "Status Report, Potamogeton clystocarpus Fern." U.S. Fish and Wildlife Service, Albuquerque.

U.S. Fish and Wildlife Service. 1994. "Little Aguja Pondweed (Potamogeton clystocarpus ) Recovery Plan." U.S. Fish and Wildlife Service, Albuquerque, New Mexico.