Grass is prissy. The temperature has to be just right or it refuses to grow. Too much or too little water makes it wither. Tread on it too often and it dies.

Weeds are rugged. They thrive on adversity, just waiting for grass to die so they can take over its spot in the sun (or lack thereof).

Weeds have been given a bad rap, mostly by obsessive-compulsive gardeners wearing polka-dot gloves who talk to their pansies. And don't forget golfers in their special shoes designed not to kill the precious grass, who blame weeds for every missed putt.

Horses are more astute than people. They know a good weed when they see one.

Of course, there is no substitute for a healthy pasture planted in grass and carefully maintained to meet the horses' nutritional needs. But the horses know that when the going gets tough-such as in a drought-and there is not enough grass to eat, certain weeds can give them vitamins, minerals, and protein.

Take dandelions, for example, a bane for anyone who wants a lawn to look like AstroTurf. The brave yellow flowers that pop up as the first sign of spring are greeted with a welcome smile as they herald an end of winter. But just let those flowers turn into fuzzy little tufts all over the lawn and out comes the weed killer.

Dandelion's nutrients

Dandelions contain a respectable amount of antioxidants and nutrition. Similar to carrots, they contain carotene and lutein. Dandelions also contain fatty acids, flavonoids, minerals (including potassium up to 4.5%); plant sterols, sugars, vitamins (vitamin A up to 14,000 international units per 100 grams); and inulin, the same potent ingredient that gives echinacea its healing properties.

A panel of herbal researchers called the Complete German Commission E found that juice from dandelion leaves produced diuretic effects comparable to furosemide, plus the high potassium content of the leaves replaces potassium loss caused by the diuretic effect.

Plantain, called "pig ears" by Northerners, contains allantoin, the same ingredient contained in aloe. Allantoin is related to allicin, the active ingredient in garlic that helps maintain intestinal flora, the beneficial bacteria in the gut that aid digestion.

Psyllium is derived from the crushed hulls of seeds extracted from a variety of plantains. It is the primary ingredient in many natural laxatives and in cereals high in fiber. Psyllium acts as a reservoir for moisture in the gut and provides crude fiber to help with elimination. Plantain also contains gums and mucilages that keep mucous membranes moist. Some herbalists even believe plantain has the ability to reduce fever.

Chickweed, golden rod, and yucca contain saponins. Saponins are used by the body to build up chemicals similar to cortisones. They act as an ammonia scavenger in the large intestine, binding it so it is less harmful to the horse and the environment. Chickweed also contains vitamin C and copper.

Yucca cuts odors

Yucca binds to sulfur in manure, the substance that causes its offensive odor. Yucca schidigera extract has been used extensively as a feed additive, especially for control of ammonia problems in commercial livestock facilities. Although research is still being conducted on the beneficial effects of yucca, it is believed to improve digestion, suppress protozoa in the large intestine, and help alleviate symptoms of arthritis.

Chicory was sold during the Great Depression as poor man's coffee. In pastures, your horse may have to scare off deer and other wildlife for the privilege of dining on this wonderful weed. Developed as a forage nearly 300 years ago in Europe, chicory has a higher mineral and protein content than alfalfa. Its deep taproot enables it to resist drought even in the hottest summer months, remaining leafy and green. Chicory also contains phosphorus, calcium, and vitamins A and C.

Lambsquarters, a low-growing plant with little triangular leaves, has a higher ascorbic-acid value than oranges and more carotene than spinach. Native Americans used

lambsquarters as a staple of their diet, especially in the spring when the vegetative state of the plant was particularly luscious.

Wild asparagus is also found in abundance in some pastures. A highly palatable source of nutrients that promote vascular health, asparagus is rich in folates, a B vitamin that helps cells grow and repair. Folates stimulate the production of blood cells in bone marrow. Rutin, another nutrient found in abundance in asparagus, strengthens blood vessels. Asparagus also contains calcium, iron, and vitamins A and C.

Crabgrass and other nuisances

Crabgrass, nimblewill, and quackgrass are perennial grasses that are considered weed problems in lawns and golf courses. There is nothing wrong with these grasses except they are rugged individualists. These nonconformists may be of a different shade of green, or have broader leaves, or even grow in luscious clumps instead of a uniform carpet like the surrounding bluegrass. Luckily for them, there is little anyone can do to completely rid turf of these undesirables except pull them out by hand, and that typically requires more effort than even the most dedicated gardener wants to devote.

In pastures, these grasses are a good source of forage. Like most weeds, they are at their highest nutritional value when they are green and leafy. Crude protein levels may reach as high as 17% with 79% digestibility. Additionally, these grasses contain calcium, potassium, magnesium, and phosphorus.

Keep them mowed

It is possible to have weeds that are too tough, of course. The more prominent the weeds become, the harder they are to swallow (and digest). This does not mean they turn into bad weeds, but they begin to channel all their energy into standing taller.

Stems become more rigid to support the taller plant, just like scaffolding. At the same time, the plants use nutrients in the soil to grow stronger stems rather than succulent leaves. Nutritional values decline, and they begin to crowd out more productive forage. It is essential to keep weeds in check, so mow often to keep them in a more nutritional, digestible, vegetative state.

Nutrition and digestibility are only a part of the story, however. Some good weeds are almost as high in nutritional value as alfalfa, but they taste terrible. Ragweed, golden rod, and goosegrass are not very palatable, and thistles are like little porcupines in a horse's mouth.

Given no other alternative in nearly barren pastures, horses may consume them anyway, so be sure to provide hay or some other forage to horses that have nothing to eat but weeds. Studies have shown that in a pinch, weeds will suffice, but horses need the nutrition and fatty acids supplied by good forage to maintain health and good body weight.