In the desert grasslands of the Chihuahuan Desert, the bunch grass known as Black Grama is common and has been important to the cattle industry because of its high nutritional value. However, episodes of drought combined with over-grazing have badly degraded the range. Like many arid-land plants, Black Grama seems to human eyes to lead a rather precarious life. In one study that monitored regeneration by seed, only 7 of the 53 years of the study produced seedlings. Good summer precipitation is a must, but good-enough is rare. How, then, do they manage to hang on?
Like any good gambler, Black Grama hedges its bets, reproducing
asexually as well as by seed. Runners, called stolons, slowly spread out from parent
plants, and if stems come into contact with the soil, rooting may occur, eventually
leading to a daughter plant. Shallow root systems spread out into barren spaces between
plants, there to gather precious water during infrequent showers. Living on the edge,
this plant has managed to survive all that nature and man has thrown at it.
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.