Juncus mexicanus is a species of rush known by the common name Mexican rush. It is native to the southwestern quadrant of the United States and parts of Mexico and Central and South America. It is a plant of moist areas in a great number of habitats, from coast to desert to mountain and low to high elevation.
This is a rhizomatous perennial herb which varies in appearance. The thin erect stems reach a maximum height anywhere from 10 to 80 centimeters. The leaves grow from the base of the stem and can exceed 20 centimeters in length. The inflorescence usually sprouts from the side of the stem rather than the tip.
The flowers grow on long peduncles. Each individual flower has thick tepals with longitudinal stripes which vary in color from bright to dark. It has six stamens with very large anthers, and long stigmas. This species is sometimes treated as a variant of Juncus arcticus or Juncus balticus.