Polypogon monspeliensis

Rabbitsfoot Grass

This is what you usually see, a field view of Polypogon monspeliensis, common name Rabbitsfoot (or Annual Beardgrass).

Showing the basal leaves.

Fresh Rabbitsfoot looks green under its white "fur."

Showing most of the plant.

Here is one of the characteristic closed panicles of Polypogon monspeliensis.

When Polypogon monspeliensis gets older and the leaves turn brown, the panicles start to shed their spikelets, leaving a bare upper rachis.

Here the plant is artificially tinted, making it look greenish as in life.

The shadows surrounding these inflorescences betray the almost-invisible thin white awns that protrude from the panicle.

Some muddy roots of Annual Rabbitsfoot Grass.

How to Identify Rabbitsfoot

  As the photos show, the usually 2-4 inch Rabbitsfoot inflorescence (seedhead) looks white and furry because of the awns on its glumes, but underneath it is light green until it dries. It actually feels soft and furry. The grass is annual. The seedhead is neither branched nor deeply lobed. I call it a "puff" and there are quite a few puffy grasses in Arizona. This one's puff is bigger and wider than most. For this reason, you must differentiate from seedheads that look puffy from a distance, like Bothriochloa barbinodis (Cane Bluestem), which has "fingers" (narrow, clustered branches) rather than "puffs." Differentiate also from the many narrow puffs that are more like short one to four-inch soda straw with rounded ends, or tiny like a Q-Tip.
  Polypogon monspeliensis grows low, usually from ankle-high to around knee-high but can be hip -high. If you can see one of its tiny spikelets with your hand lens, it is V-shaped and the awns protruding from the glumes are much longer than the thick, lower part of the body of each glume.

Similar Species

  There are five puffy Polypogon species in Arizona. Two of them, P. monspeliensis and P. viridis (Water Beardgrass), occur in every county. The key difference is that Water Beardgrass lacks glume awns. To be certain you must check the glumes for awns, plucking out a few tiny "seeds" and using your hand lens. Another difference is that the panicles of Water Beardgrass have visible lobe-like branches (unlike most Rabbitsfoot panicles). The other three species are rare and of restricted provenance, so you are unlikely to encounter them:
  Polypogon interruptus (Ditch Beardgrass) occurs in all counties except GRA, GRE, MOH and PIN. The seedhead of Ditch Beardgrass is obviously branched (lobed), or "interrupted." The glume awns are much shorter (about 1/8 inch) than in Rabbitsfoot (about 3/8 inches).
  Polypogon elongatus (Southern Beardgrass) occurs only in PIM. Its seedheads are much longer than the others, up to a foot!
  Polypogon australis (Chilean Beardgrass) occurs only in COCO. The glume awns are longer than those of the similar P. interruptus but much shorter than those of Rabbitsfoot.