A strange thing at this time of year for those who have not lived here long is the simultaneous advance of winter and spring. We belong to a climate that is Mediterranean-- it is wet in the winter and very dry in the summer. It is also temperate--that is, there are hot and cold seasons here, even if some people to the east and north of us might argue the point. It is cold enough that many native plants shut down and give up their leaves for the winter. The grasses through, are hard at work. For them, one could say that spring is now arriving.

By Thanksgiving in a normal year, our golden hills have begun to transform into a soft green rolling carpet of young grass, a living color that can take your breath away when sunlight falls on it. I realized recently that I didn't know much about grasses. As usual, a little research turns up some interesting information about the natural world and our own valley.

Similar to sedges and rushes, but more common and more intimately linked to the human world, grasses have been with us since the beginning of agriculture, as long as 7,000 years ago. In the plant world, the Grass family, or Gramineae, is the third most abundant after the Daisy and Orchid families. There are nearly 10,000 known species. Grasses cover nearly a third of the earth, and nearly one half of the United States. They can be found in the Arctic, in salt water, at the equator, and in dry, marginal landscapes around the earth--only algae and lichen are more tolerant of extremes.

Grasses differ from the sedges and rushes. A key grass feature is that a grass leaf encircles a rounded stem to form a "sheath". This sheath is at least partly open. They have hollow stems except at their joints, or "nodes", where the leaf is attached. Their tiny unique flowers are also an important distinguishing feature, and are often used to discern between species. All grasses are pollinated by the wind, so the flowers have not evolved to be showy and attract insects or other pollinators. Instead they produce large quantities of pollen. These prolific pollens are renown, especially to those with hay fever here.

Their tolerance and ability to dominate the plant world come from several special adaptations. Most of a grass plant is underground. Their roots contain as much as ninety percent of their biomass. Because they tend to grow in drier climates, this gives them a strong advantage in saving water--a plant with most if its biomass above the surface soon dries out. Their roots are efficient at branching and take advantage of all available soil space, which benefits the land by anchoring the soil and benefits the plant by blocking plant competitors from finding root space. Many grasses also have creeping stems. At the surface these stems are called rhizomes; just under the surface they're called stolons. These can produce roots and new stems at any node and quickly form a dense mat, further insuring a competitive edge. In addition, a grass leaf grows from a base and has parallel veins. This enables it to be clipped by a grazing animal, or a human mower, and continue to grow.

Most of the grasses we see here now are invasive plants, or "exotics", starting 150 years ago when the mission was founded and livestock and feed were brought in. In a system of interconnected elements-- introduction of exotics, grazing, fire suppression, and fences that lock livestock into a fixed range--each appears to contribute to increased exotic grasses and the loss of native grasses here. Exotics now dominate the landscape and have produced great changes, including increased runoff, less soil stability, and hills that turn brown earlier since most of these exotics are annual grasses with more shallow roots and which die off each summer. Undoubtedly, as they must set much more seed, these exotics also produce more pollen in hay fever season. Native grasses still can be found on the cooler hill slopes and poorer soils, typically as bunch grasses that are "perennial", that is, they live for several years.

Of nearly 10,000 species identified in the Grass family, a mere handful are responsible for most human calories. Grasses are consumed indirectly by the animals that make up meat and dairy products, and their fruit, or "grain", are the major cereal crops: wheat, rice, corn, oats, barley, rye, sorghum and millet. Even the sugar that most of us use to sweeten our cereals and breads comes from grass--the sugarcane.

Lawns are also grass, a strange decorative convention that most of us don't think about. The statistics are staggering: Nationally, we raise 3.2 million acres of lawns, more than any other crop. We spend about 30 billion dollars a year keeping our grass from growing as it would naturally, using enormous amounts of fertilizers, pesticides, and water.

Linked not just to humans, but to many of the animals that share our valley, grasses are key to the abundance and the beauty that frame our lives here. It is worth noting them as they welcome "spring", just as winter arrives.