by Bala Chaudhary,
Native Plants Class 2003
Common names: Indian ricegrass, sand grass, Indian millet
Family: Poaceae
Synonymy: Eriocoma cupidata Nutt., Oryzopsis
hymenoides (Roemer & J.A. Schultes) Ricker ex Piper, and Stipa
hymenoides Roemer & J.A. Schultes.
Etymology: The previous genus name, Oryzopsis comes from
Greek, meaning “rice like”. Hymenoides means membranous. (1)
Identification
Growth form:
Dense bunchgrass reaching 30-70 cm in height. (2, 4).
Roots:
Sheath: Leaf sheaths can be hairless or covered with
scales and rough to the touch. They are round, split, prominently veined,
usually with a fringe of hairs at throat. The base of leaf sheaths is
often purple (2, 4).
Leaves: Leaf blades are firm, narrow (5mm), and nearly
as long as the stems; margins are typically involute, or rolled inward
(2, 4).
Ligules: Ligules have tufts of hair on either side and
are 3-8 mm long on the main stem leaves. (2)
Inflorescence: Inflorescence is a diffuse panicle, 5-15
cm long and nearly as broad. It branches dichotomously and the branchlets
and pedicels spread divaricately. The pedicels, diagnostically thin and
kinked, are 1-2 cm long. Spikelets are 6 to 10 mm long and contain a single
flower (2,4).
Glumes: The glumes are acuminate (form a tip at the end)
or short-aristate (have short bristles) and are 5-8 mm long. They can
be hairless, scaly, or finely pubescent. They also have three deep nerves
running lengthwise (2, 4).
Lemma: The lemma is 3 to 5 mm long and covered with soft
shaggy unmatted hairs 2-4 mm long (X). It appears dark brown to black
at maturity (2, 4).
Awn: The awn is 3-6mm long, stout, and can be slightly
twisted (2, 4).
Caryopsis: The seed is plump, dark-colored, rice-like,
and can be up to 2mm (4).
Similar species: Thirteen other species of Achnatherum
can be found in Arizona. Achnatherum hymenoides can be distinguished
from the others by its long spikelet (6-10 mm), presence of hairs on the
lemma, and large diffuse panicle. (5)
Ecology
Life history: Perennial grass
Native/introduced: Native (6).
Photosynthetic pathway: C3 (6)
Phenology: Indian ricegrass flowers from May to August
(2, 4).
Distribution: Indian ricegrass grows in dry, open, sandy
soils of desert scrub, sagebrush shrubland, and pinyon-juniper woodland.
It grows at elevations between 3500 and 6500ft and is found in Arizona
in Apache, Navajo, Coconino, Mohave, Yavapai, and Pima Counties. It is
a widely distributed grass in western North America and can be found from
Manitoba to British Columbia, south to Texas, California and northern
Mexico (2, 4).
Uses
Native Americans used Indian ricegrass as a food grain. It was also cut
for hay and can be a good forage grass.
References
1. Gledhill, D. 1989. The Names of Plants. Cambridge University Press.
New York, NY.
2. Gould, F. 1988. Grasses of the Southwestern United States. University
of Arizona Press. Tucson, AZ.
3. Hickman, J.C. 1993. The Jepson Manual: Higher Plants of California.
University of California Press. Berkeley, CA.
4. Hitchcock, A.S. 1971. Manual of the Grasses of the United States. Dover
Publishing. New York, NY.
5. Kearney T.H. and Peebles R.H. 1960. Arizona Flora. University of California
Press. Berkeley, CA.
6. USDA, NRCS. 2002. The PLANTS Database, Version 3.5 (http://plants.usda.gov).
National Plant Data Center, Baton Rouge, LA 70874-4490 USA.
