Blue grama, Bouteloua gracilis, is a native, long-lived perennial, warm season, short grass, monocot, of the grass family, that is abundant on healthy, mixed grass prairie plant communities. Blue grama can grow on sandy, shallow, silty, overflow, clay, and thin claypan ecological sites. It grows better on silty sites. It is drought tolerant, moderately tolerant of alkaline soils, however, its not tolerant of shading or flooding, and intolerant of acidic and saline soils.
Lead tiller early aerial growth arises from carryover tillers and basal leaf growth resumes from the basal tillers on short rhizomes. New leaves are visible during mid April which is a little earlier than other warm season grasses. Leaf growth is slow until early or mid May. Basal leaf growth is at 19% height during late April and at 34% height on mid May. More rapid growth produces 3.5 new leaves at 69% height on mid June. Basal leaf is at 97% height on mid July and at 100% maximum height on late July. Early flower stalk growth reaches the boot stage after mid June. Stalk growth progresses through head emergence and is at 68% height during late June. The observed flowering stage can occur during a long 5 week period from early July through the first week of August. The documented first flowers appear 16 July, with the mean first flowers recorded to occur on 18 July. The flower stalks are at 80% height during mid July and at 100% maximum height during early August. Seeds are developing during late July, they reach maturity during mid August, and start being shed during late August to early September.
Lead tilers contain 15.9% crude protein during early June, it is at 14.8% during mid June when the 3.5 new leaf stage is reached, it is at 13.1% during early July, and drops below the requirements of lactating cows during the fourth week of July. Lead tillers drop below the phosphorus requirements of lactating cows during early August.
Vegetative tillers arise from fall produced crown tiller buds and produce 5 to 7 basal leaves by mid to late July. A few vegetative tillers continue growth and produce leaf 8 or 9 during late July and August. Tillers with 5 to 7 leaves lose leaves 1 and 2 to senescence but maintain all other leaves as photosynthetically active leaves. Tillers with 8 or 9 leaves usually maintain 4 or 5 photosynthetically active leaves. Levels of crude protein in vegetative tillers increases above 9.0% during August to 10% during early September, then decreases during September, and drop below 9.6% during late September. These tillers will survive the winter as carryover tillers becoming reproductive lead tillers during the successive growing season.
Secondary tillers develop during the growing season in May and June from axillary buds on lead tillers. They grow slowly until they produce their fourth leaf and become independent developing as vegetative tillers usually by July or August.
According to OA Stevens (1963), Blue grama is our most valuable native pasture grass for drier soils. Blue grama produces a great quantity of nutritious quality forage. Its short stature belies the importance of its contribution to the mixed grass prairie. The mat forming aboveground parts cover the soil protecting it from heat and erosion holding the prairie plant communities together. The high density of tillers prevents undesirable species from invading. The deep roots descend to 6 feet helping soil formation and the dense shallow roots stabilize the soil from moving and permit rapid plant response to low precipitation events. The huge quantity of nutritious forage produces a large portion of the livestock weight performance.
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