Bouteloua gracilis

Blue Grama

Blue Grama has its inflorescences high above its basal leaves. You want your pollen to blow in the wind, not get stuck in the leaves.

Blue Grama has thin stems (culms) and only a couple of eyebrow-like branches.

Blue Grama stems (culms) are thin and usually have only a couple (one to three) eyebrow-like branches above.

Blue Grama can be colorful!

Blue Grama grass in Williams, AZ

Blue Grama has a thick basal leaf patch and a varied leaf width.

The roots of Blue Grama grow outward from its tuft-like bunch.

Bouteloua gracilis roots. The lower leaves are thin here but can be a quarter inch wide.

When dry, the eyebrow-like branches curl up.

Blue Grama in anthesis. The yellowish anthers have protruded from between the lemmas and paleas. They are shedding their pollen to the wind.

A rachis with its spikelets (glumes, lemmas, and paleas) to the left. On the right, tiny hairs run along the rachis.

How to Identify Blue Grama

At first glance, Bouteloua gracilis, a perennial, is another easy one. Many people are familiar with this common grass, which occurs in every Arizona county. However, the eyebrow-like inflorescences can be tricky, as several other regional grasses are similar.

My best way to differentiate from other gramas is that there are usually only one or two eyebrows per stem on B. gracilis. The eyebrow-branches tend to curl upward as they dry, the better to release the seeds. Blue grama grows from ankle high to just above knee high, so it is a rather short grass. At the beginning of August after a week of monsoon rains, Blue Grama at 7,000 feet altitude was abundant and healthy--not yet in anthesis. But by mid-August the grass was in full anthesis, with the anthers all hanging out.

Similar Species

Anywhere in Arizona, you might encounter the scarcer but very similar Bouteloua hirsuta whose common name is Hairy Grama. However, it is easy to tell the difference if you look closely at the "eyebrows." In B. hirsuta the rachis that holds the seeds (spikelets) extends about one-half inch beyond the rest of the eyebrow, as you can see in this picture. (Graph paper is in quarter inches). This rachis (branch) looks like an awn but is actually an extension of the branch. Bouteloua hirsuta, with its Extended Rachises.
Also, in every county, watch out for Bouteloua barbata (Sixweeks Grama) which has similar eyebrows that also curl. The difference is that each Sixweeks stem has about 4 to 9 eyebrows that are usually smaller. Bouteloua barbata, Six-weeks Grama, with its 4 to 9 branches..