Wild rice, Texas

Zizania texana

division: Magnoliophyta

class: Liliopsida

order: Cyperales

family: Gramineae

status: Endangered, ESA

range: USA (Texas)

Description and biology

Texas wild rice is a coarse, aquatic grass with long, under-water stems. It is classified as a perennial (plant that lives, grows, flowers, and produces seeds for three or more consecutive years). Its leaves are green, thin, flat, and very long. They measure up to 45 inches (114 centimeters) long and 0.25 to 1 inch (0.64 to 2.54 centimeters) wide. The lower part of the grass, with leaves, often floats on the water. This part of the plant can measure 3.5 feet (1.1 meter) long.

Flower stalks, when present, extend 12 to 35 inches (30.5 to 89 centimeters) above the surface of the water. The plant flowers and produces grainlike seeds at various times from April to November. Texas wild rice is related to the wild rice plants that people eat, but it is not used for food.

Habitat and current distribution

This grass species is found only in a 1.5-mile (2.4-kilometer) length of the headwaters of the San Marcos River in south-central Texas.

Texas wild rice forms large clumps that are firmly rooted in the gravel bottom near the middle of the river. It prefers clear, cool, fast-flowing spring water. An increase of silt (mineral particles) in the water, the disturbance of the river's bottom, and stagnant water all will kill the plant.

History and conservation measures

Texas wild rice was first identified in 1933. At the time, it was abundant in the headwaters of the San Marcos River, in nearby irrigation ditches, and for about 1,000 feet (305 meters) behind Spring Lake Dam. Within 30 years of its discovery, the plant had almost completely disappeared from Spring Lake. Its numbers were drastically reduced in other areas throughout its range. Today, Texas wild rice plants that flower are rarely seen.

The primary cause for the decline of this species has been the destruction of its habitat. The damming and dredging of the San Marcos River, an increase of sewage and chemical pollutants in the water, and human recreational activities, such as boating and swimming, have all played a role in damaging the plants' habitat.

Because of human population growth in the area, the flow of water from the San Marcos Springs has been reduced. Some experts predict that the flow will cease shortly after the year 2000. Efforts have been made to transplant Texas wild rice, but these efforts have been unsuccessful.

In order to save Texas wild rice, the U.S. Fish and Wildlife Service recommends that a public education program focusing on the plight of the plant be established. In addition, all remaining Texas wild rice habitat must be protected.