Blue grama — October 2009

blue gramma backlit

     Our native plant for this month may not be the most eye-catching or conspicuous plant of Deer Canyon Preserve, but if we were to rate all our native plants according to the number of individuals growing on the Preserve, blue grama grass would clearly be at the top of the list. It is the dominant grass in the rangelands of our region and it grows profusely in virtually all open areas of the Preserve. The scientific name of blue grama is Bouteloua gracilis. Bouteloua honors the brothers Claudio and Esteban Boutelou, Spanish gardeners who lived in the late 18th and early 19th centuries. The Boutelou brothers planted and maintained the living collections brought back to Spain from the New World by the Spanish botanists Sesse and Mocino who headed the Royal Botanical Expedition to New Spain from 1787–1803. The species name, gracilis, is a Latin word meaning slender and graceful which aptly describes the leaves of blue grama. Bouteloua gracilis is also known by the common names graceful grama grass, signal-arm grass, eyelash grass, and mosquito grass.

blue grama spikelets

     Blue grama is a warm season perennial grass that tolerates drought, salinity, and modest alkalinity. It does not grow in dense shade, flooded areas, or acid soils. The highly branched, shallow root system of blue grama is able to quickly absorb any available moisture. Its bluish green leaves are relatively short (3–6”), flat, narrow, and taper to a point.

blue grama anthers

     In the late summer blue grama sends up 7-18 inch tall flowering stems that bear 1 to 3 branches which stick out at a right angle from the stem (hence the name signal-arm). Each of these side branches is adorned with 20-90 tiny flowers called spikelets. The flowers of grass plants are specialized for wind pollination and produce anthers (pollen-bearing structures) that dangle from each flower which appear light green in the photo above. After pollination, a small seed develops in each flower and when mature, the branch bends forming an arc that helps to separate and disperse the seeds (hence the name eyelash – see the photo below). Like many bunchgrasses, blue grama also reproduces asexually by a process called tillering which involves sending out stems from the base of the plant that may establish new clumps of leaves.

blue grama eyelashes

     In 1973, Bouteloua gracilis was designated as the official state grass of New Mexico. A most appropriate choice, blue grama has long been recognized as an excellent livestock food with a high protein content. In addition, it tolerates close grazing and is palatable all year. Blue grama also provided nourishment for some Native Americans when the seeds were ground with corn meal and water to produce mush. Other records indicate that its stems were tied together to make a fine brush used to clean metates. Local lore has it that blue grama is useful in forecasting the severity of the upcoming winter. When most of the flowering stems bear one spike, a mild winter is anticipated, but when two or more spikes appear on most of the flowering stems, prepare for the worst. According to my brief and completely unscientific recent survey, I have no plans to invest in snowshoes for this winter.

A Botanical View – The Grasses: A Particularly Important Family of Plants.

     The grass family, Poaceae (formerly Gramineae), while often overlooked, is a widespread and extremely useful group of plants. In New Mexico the Poaceae, with 118 genera and 424 species, is second only to the Asteraceae (see last month’s essay) with respect to statewide diversity. The genus Bouteloua, by the way, has 16 native species in New Mexico. On a global scale, grasses are the fourth most diverse family based on number of species (approximately 9,700), but they are unsurpassed among the world’s flowering plants in terms of the amount of land surface area dominated. And some species of grass even thrive in aquatic habitats.

     The extensive ecological success of grasses is perhaps exceeded by their economic significance. More than any other plant family, grasses feed the human population. Humans have cultivated cereals for over 10,000 years and the advent of agriculture is widely regarded as the key to the development of civilization. Today, the majority of the calories consumed by the human population come from members of the Poaceae. The four most important crops in terms of worldwide production are all grasses (wheat, rice, maize, and sugarcane). Beyond feeding humanity, grasses are used for food and habitat by countless animals, both wild and domesticated. Bamboo is becoming increasingly important as a construction material as well as providing fiber for paper and pulp for rayon. Grasses are particularly useful in erosion control efforts, preventing the loss of valuable topsoil. We play most of our games, both professionally and recreationally, on grass and the presence of natural expanses of meadows and other grasslands significantly enhances our enjoyment and appreciation of many natural habitats. So many aspects of our way of life, perhaps our very existence, rely directly on this unassuming, often inconspicuous group of plants. I wonder when the last time was that any of us thanked a grass?

© 2009 Jerry Melaragno

Downloadable essay here.

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