Big Galeta
Pleuraphis rigida
(Hilaria rigida)
Sketched from live specimen in Butler Valley, La Paz County, AZ. 06 April 1993.
PERENNIAL GRASS: This long-lived grass takes on a shrub-like morphology with multiple above ground branches and woody (lignized) lower stems and reaching a height of 1 m.
FLOWERS: A narrow spike on a twisty stem
consisting of closely appressed spiklets appearing three per node. A series of
short awns on each spikelet.
LEAVES: Leaf-blades are cauline, i.e. dispersed along stems as opposed
to not restricted to base as in many grasses.
RANGE: Fairly common in the Sonoran Desert of Arizona on plains, sand
dune areas, and adjacent to washes. Also ranges into Mojave and Chihuahuan
Deserts.
FRUIT: A grain.
UNARMED.
Family: Poaceae
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In Rainbow Valley, Maricopa Co., Arizona, Sept. 2009, I found many P. rigida blooming and setting seed. About every fifth plant had seed heads infected with and swollen-black by infection of smut, Ustilago sp. fungus. Another smut fungus occurs on Bermuda Grass (Cynodon dactylon).
Smut fungus (Ustilago) in a grain of P. rigida. The mature spores fill the seed hull which ends up growing several times larger than usual. The spores are black, appearing like soot. Photographed in s.w. Maricopa Co., Arizona, USA. Sept. 2009.