Side Oats Grama Grass
This native, warm-season grass is distinct from its grama cousins.
Side Oats Grama is one of four grama grasses found in Illinois, and, by far, the most common. Grama comes from the Latin word grāmen, which means grass. The grama grasses (now that's a bit redundant isn't it?) belong to the genus Bouteloua, which is a fun Latin name to pronounce.
Where Side Oats grows
Side Oats Grama (Bouteloua curtipendula) is a native, warm-season grass that can be found in northern Illinois as well as counties in west-central and southern Illinois. You can find it growing in drier prairies sites, as well as glades and barrens.
What Side Oats looks like
How do you identify Side Oats Grama? And how do you tell it apart from the other three, Buffalo Grass, Blue Grama, and Hairy Grama?
- Side Oats Grama is a short, slim grass, typically 2-3 feet tall.
- A helpful identification characteristic for this grass is the hairs that you can find along the margins, or the edges, of the leaf blades.
- These hairs are held on small glands along the edges of the leaves, and later in the season, you can still see the glands remaining when the hairs have fallen off (below, outlined in white).
The inflorescence of this grass is unique – it will develop a raceme inflorescence with a zig-zag rachis (stem of the inflorescence).
- The spikelets can be found in small clusters held on a stalk.
- The individual spikelets are awned, albeit with very short awns.
- The spikelet clusters resemble short eyelashes.
- The spikelets can be green to red in color, and turn brown in the fall (right).
- If you are lucky enough to catch this grass in flower, it has bright red anthers that you can see exserted (pushed out) from the spikelets (left).
As the season progresses, the inflorescence often nods to side, which leads to the name "Side" Oats Grama; the spikelets will hang off one side of the rachis.
Other grama grasses
The three other grama grasses are all shorter in stature, typically under 1 foot tall. In Illinois, you are most likely to see them in the northern counties.
- Blue Grama (Bouteloua gracilis) is rare in Illinois, found in only a handful of counties
- Hairy Grama (Bouteloua hirsuta), closely resembles Blue Grama and is found in the northwest counties of the state.
- Buffalo Grass (Bouteloua dactyloides) is found in the northeast counties of Illinois.
Besides the size of the grasses, the easiest way to tell them apart is by their inflorescences.
- Blue and Hairy Grama have raceme inflorescences with dense clusters of spikelets about 1-2 inches long (two to three times the size of the clusters of Side Oats Grama) that very much resemble an eyelash.
- Hairy Grama is much hairier than Blue Grama, has shorter racemes, and its clusters of spikelets do not extend across the entire branch, leaving a pointed tip (above, top right).
- In contrast, the spikelets of Blue Grama extend across nearly the entire branch of the cluster (above, top left).
- Buffalo Grass differs because it is dioecious, which means it produces separate male and female flowers (above, bottom), which are found on different plants. The spikelets of the male flowers are held in small clusters on stalk, more closely resembling Side Oats Grama. The female flowers are reduced.
Each of these three grasses is much smaller in size and much less common in Illinois than Side Oats Grama.