Pictured from left to right: Bouteloua curtipendula (2 photos) and Bouteloua gracilis
This genus is characterized by basal leaves and ligules consisting of a ring of hairs. Inflorescences are the most distinctive feature. They consist of 1 or more spike-like and 1-sided branches bearing numerous sessile spikelets in 2 rows along a flattened or angular main axis. All spikelets have 1 fertile floret and 1 to 3 sterile or rudimentary florets. Lemmas are 3-nerved with the main (central) nerve becoming the awn; the lateral nerves may also extend as short awns. Paleas have 2 nerves.
There are 3 species in MN; 3 native.
Bouteloua curtipendula (boo teh loo' ah kur tih pen' dew lah)
- Synonyms: None
- Common names: side-oats gramma; Lakota: wapaha kamnimnila peji
- Origin and habitat: Native; open habitats; also planted as a roadside soil binder
- Identifying characters: Inflorescences consist of a long central axis, up to 1.5 dm long, with short, widely spaced branches turned to one side and generally at right angles to the main stem. Leaf blades are flat with marginal hairs.
- Comments: When the stamens are releasing their pollen they are a lovely cinnabar-red, contrasting beautifully with the bluish green of the inflorescence. This species is occasionally used as a specimen plant in the garden. It is very drought tolerant. It is also a choice food plant for grazing animals.
Bouteloua gracilis (boo teh loo' ah cur tih pen' dew lah)
- Synonyms: None
- Common names: blue gramma, buffalo grass, mosquito grass; Lakota: peji okijata
- Origin and habitat: Native; dry open prairies
- Identifying characters: This species is easily recognized by its often-circular mats of very short, tufted, and curled leaves. Leaf blades are minutely pubescent on the upper surface but occasionally have scattered long hairs. The ligule is a typical fringe of hairs but with longer hairs at the margins. Inflorescences look like dark, dense, miniature combs; 1-4.5 cm long. Spikelets are 2-5 mm.
- Comments: At first the inflorescence is oriented so the spikelets hang downward (looking like a row of mosquitoes feeding and hence the common name). As the flower and fruit mature, the axis of the inflorescence curves backward bringing the spikelets to an upright position where the fruits can easily be dislodged and dispersed.
Bouteloua hirsuta (boo teh loo' ah her sue' tah)
- Synonyms: None
- Common names: black gramma, buffalo grass, hairy gramma
- Origin and habitat: Native; dry open prairies, usually on more sandy soils.
- Identifying characters: Very similar to blue gramma (B. gracilis), differing primarily in having the inflorescence axis extend beyond the uppermost spikelets as a stiff bristle, often longer than the adjacent spikelets. Leaf hairs are much longer and more obvious.
- Comments: (See additional comments under B. gracilis). This species and the previous are sometimes referred to as buffalo grass. They should not, however, be confused with another buffalo grass, Buchloe dactyloides, which is on the state Special Concern list of rare plants. This latter buffalo grass is smaller in stature and the inflorescences are unisexual. Its staminate inflorescence looks like Bouteloua but its carpellate inflorescence consists of only a few florets produced in a bur-like structure found hidden near the soil surface. It is the Buchloe that is sold as a salt-tolerant substitute for curbside lawns.
Additional Species in Minnesota:
Copyright 2002, A.F. Cholewa, J.F. Bell Museum of Natural History, University of Minnesota / No portion of this guide may be duplicated without written permission of author.