Sunday, May 30, 2010

Rice Grass

What’s blooming in the area: Tamarix, Austrian copper and double pink shrub roses, Apache plume, snowball, silver lace vine, skunkbush, yucca, red hot poker, peony, tumble mustard, western stickseed, cryptantha, fern-leaf globemallow, oxalis, alfilerillo, white evening primrose, bindweed, alfalfa, Dutch and yellow sweet clovers, white and purple locos, sweet pea, purple salvia, native dandelion, goat’s beard; June, brome, needle, rice, and three-awn grasses; buds on milkweed; buffalo gourd up; cheat grass turning red.

In my yard: Spirea, raspberry, beauty bush, iris, winecup, oriental poppy, Jupiter’s beard, snow-in-summer, Bath’s pink, sea pink, baptista, catmint, pink salvia, blue flax, vinca, pink evening primrose, golden spur columbine, chocolate flower, blanket flower, perky Sue and Mount Atlas daisy; buds on Persian yellow and Dr. Huey roses, daylily, hollyhock, coral bells, snapdragon, anthemis and coreopsis; buddleia has new growth from root; last year’s morning glories up.

Bedding plants: Zonal geraniums, nicotiana.

Inside: Aptenia.

Animal sightings: Rabbit, hummingbird, gecko, ladybug, cricket, baby grass hopper on first blanket flower, large black harvester and small red ants.

Weather: Ice in hose Tuesday morning, near 80 when I got home at night; a little rain Friday; winds began almost every day by late morning; 14:22 hours of daylight today.

Weekly update: This is the time when needle grass is at its peak. Foot long strands of fine hair and unreleased seed ripple in streams of white light that follow ridge lines across the river and reveal the underlying shape of dissected foothills.

Here and there along the edges, an occasional clump of rice grass grows, shorter and squatter. The narrow green leaves look the same, but needle grass blades tend to open flatter. The stalks end in crisscrossing U-shaped branches with globular cases at the tips, each holding a single rounded dark seed.

I always let Achnatherum hymenoides grow from a superstitious respect for things I suspect have survived from the distant past. Today it’s found from the Nebraska sand hills to the Cascades, from lower Canada to northern México. There is a general belief that it was once grew in pure stands in areas like Utah, but that it was decimated by overgrazing beginning in the 1870's

Archaeologists think it was widely eaten in the distant past. However, when corn was adopted by the Anasazi, it became less important. Michael Brand found it reported in most of the Basketmaker and Pueblo sites he reviewed, but there appeared to be a slight decline in use through time. It appeared more often in charred remains and pollen studies, then in fossilized feces.

Anthropologists recorded its use in the recent past among the Hopi, Zuñi, White Mountain Apache and Navajo, including those near Chaco Canyon. The Hopi, however, considered it a famine food that had been eaten in the past.

I noticed that for something that was supposed to be native, it didn’t increase when left alone. Instead of producing new seedlings, the clumps grew by adding segments to the outer perimeter, and dying in the middle, creating a fire hazard. People trying to restore lost grasslands or reclaiming disturbed sites have reported it doesn’t germinate reliably, and when it does emerge, it begins to die out after five years.

Oryzopsis hymenoides, as it once was known, is so well adapted to the lands west of the Continental Divide that it doesn’t respond to modern cultivation. The dormant embryos are protected by a hard shell that doesn’t begin to disintegrate for several years so there’s seed available in those rare wet years when it can emerge.

Even though the plants are wind pollinated, the perennial bunch grass compensates for its sparse distribution by fertilizing itself. Many of the seeds are sterile and remain on the plant, while the heavier, viable seed is quickly prepared for release. During this time, the seed stalks become unpalatable to discourage grazing by rabbits and other predators.

Researchers led by Kent McAdoo discovered that rodents in the pocket mice and kangaroo rat family removed the outer shell before storing seeds for future use and that those cached seeds were the primary source for stand renewal in the area they observed. The local harvester ants and deer mice also bury the seeds, but they don’t aid germination, only themselves.

Almost as soon as the seedlings emerge, sand grains collect around the fibrous roots. Leroy Wullstein found the rhizosheaths aided nitrogen fixation and helped prevent water from escaping.

The life cycle, however, is more dependent on heat than water: it does well facing south, and doesn’t tolerate shade. In my yard, it grows in the drive and on the windy, eastern side of the house. In the area, I don’t see it in the established needle grass prairie, but along the roads near the arroyos.

Established clumps begin growing, when the soil temperature at the tips of the roots reaches 39F degrees for three or four days. Although water helps, the plant height, usually about a foot in my yard, is related to soil temperature.

Come summer, the leaves and stalks dry light brown, creating cured winter forage. During this annual drought, carbohydrates concentrate in the plant’s crown, not the roots. When the monsoons arrive, when they come, the bases green slightly for the winter and the carbohydrates decrease.

When water fails, plants may die and seeds stay buried until the weather improves. In the rio arriba, one can only be sure the current year won’t repeat the past, but not even nature can predict if it will be better.

Notes:Brand, Michael James Brand. Prehistoric Anasazi Diet: A Synthesis of Archaeological Evidence, 1994.

Bristow, Caryn E., G. S. Campbell, L. H. Wullstein and R. Neilson. "Water Uptake and Storage by Rhizosheaths of Oryzopsis hymenoides: a Numerical Simulation," Physiologia Plantarum 65:228 - 232:1985.

Jones, T. A. "A Viewpoint on Indian Ricegrass Research: Its Present Status and Future Prospects," Journal of Range Management 43:416-420:1990; summarizes research of others.

McAdoo, J. Kent, Carol C. Evans, Bruce A. Roundy, James A. Young and Raymond A. Evans. "Influence of Heteromyid Rodents on Oryzopsis hymenoides Germination," Journal of Range Management 36:61-64:1983.

Moerman, Dan. Native American Ethnobotany, 1998; summarizes data from a number of ethnographies.

Tirmenstein, D. "Achnatherum hymenoides," 1999, United States Forest Service, Fire Effects Information System, available on-line.

Wullstein, L. H. "Nitrogen Fixation Associated with Rhizosheaths of Indian Ricegrass Used in Stabilization of the Slick Rock, Colorado, Tailings Pile," Journal of Range Management 37:19-21:1980.

Photograph: Rice grass growing next to the back porch, 27 May2010.

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