Grasses, family Poaceae, are among the most recently evolved plant categories. They are generally inedible to humans, but the seeds of some are the staples of life for us - rice, wheat, barley, corn and other grains. Grasses are also indigestible to cows, sheep, goats and horses, but they chew them up so bacteria can digest them easily, then absorb nutrients produced by the bacteria. Pandas and some lemurs can eat grass directly, bamboo anyway, but they had to develop an inexplicably high tolerance for toxic cyanide to do so.
Grasses are descended from that same primitive magnolia all flowering
plants are descended from, but are on the Lily side of the great Liliopsida
/ Magnoliopsida divergence. Like the lilies they descend from, grasses are
monocots (the seed sprouts just one first leaf, not two) and their leaves
are long and narrow with parallel veins.
General & History
Grasses are a recently evolved family of flowering plants. There were no grasses in the days of the dinosaurs, only herbs, ferns, cycads, rushes and conifers - and the ever increasing offspring of a primitive magnolia, ancestor of all flowering plants. Grass-like plants first appeared about 65 million years ago, right at the extinction of the dinosaurs.
Grasses now cover vast areas of the world. In some areas not because they drive out other plants but because they are beneficial to man. The Great Plains of the U.S., were artifically created by the Native Americans by burning forests so the buffalo whould have plenty grass for forage. The burning is no longer done except in parts of Canada, so where the plains are not farmed they are slowly reverting to forest.
Grasses range in size from far smaller than lawn grass to giant timber bamboo which can grow to around 100 feet tall. A few grasses developed concentrated seed heads with a heavy yield of medium to large seeds. This made them efficiently harvestable for human and animal food. Humans further developed these by selective breeding to create modern grains. The most important characteristic developed is that the seed heads do not "shatter", but stay together until all seeds are fully mature so they can be efficiently harvested. The largest seed heads belong to a grass called "corn" in the U.S. and "maize" most other places.
All grasses are built much the same, They belong to the Lily (Liliopsida) branch of the Magnoliophyta which means they are monocots. Their seeds sprout only one first leaf and their adult leaves are long and slender with parallel veins. Specific to grasses are hollow stems plugged at intervals called "nodes" (think "bamboo") and dense clusters of flowers that form seed heads. Grasses propagate not only from seed but from runners, sometimes very aggressive runners, that sprout new plants around the parent.
Other than their seeds, few grasses are used for human consumption because the foliage is generally tough, fiberous, not particularly flavorful and often highly toxic. Cows, sheep and goats live happily on grasses by chewing them up and running them through multiple stomachs where bacteria digest the grasses and the animal absorbs nutrients manufactured by the bacteria. Horses, having a more omniverous digestive system, are not so good at surviving on just grasses. In the wild they will happily kill and eat any animal they can catch (and have killed and eaten people).
Certain grains can be sprouted from seed, then eaten or squeezed into juice before they become too tough and toxic. Some health enthusiasts ascribe miraculous properties to these sprouts. Of course sprouts do have miraculous properties - sprouts of wheat and barley are critical to the making of beer, one of the earliest of man's community endevours and possibly the original purpose for farming.Health & Nutrition
Disclaimer: The information here is from publically available material and is not to be considered medical advice. For medical advice consult degreed physicians and other duly authorized authorities. Unfortunately they often don't seem to know much more than the rest of us, but at least it's "official".
General Nutrition: Grains are high in proteins, but these proteins are never a complete set, though rice comes fairly close. Corn is particularly deficient in both proteins and the vitamin niacin. This has caused severe health problems in many parts of the world. This is explained in detail in the corn pages.
In any case, a diet heavy in grains must be supplemented with either beans or meat. The cost of sufficient meat is too high for most of the world's population, but beans are cheap and come in many varieties.
Celiac Disease: Grains of the wheat family contain a protein called "gluten". Something like 1% of the population of North America has a genetically caused problem with this. The protein causes an auto-immune reaction that is very painful and will eventually destroy the intestinal lining. There is no cure, so persons with this problem must avoid foods with even a tiny bit of gluten.
Not all grains contain gluten, only wheat and grains closely related to wheat. Unfortunately, wheat and its relatives are used in a tremendous number of food products which must be avoided. This known problem with gluten has spawned an avoidance of gluten even by many health concious people who do not have the celiac problem and this has spawned a growing "gluten free" segment of the food processing industry.
Alergies Wheat in particular is implicated in quite a lot of alergies that are not associated with celiac disease. Other grains may cause alergic reactions in some people.
Toxins in Whole Grains: Like other plants, grains have strategies to discourage predition. In whole grains you will find phytic acid (inhibits mineral absorbtion), lectins (mimic insulin, hormones, cause alergy problems and excess fat storage), protease inhibitors (liver and lung problems) and goitrogens (interfere with thyroid function).
These toxins and other grain problems ave caused a number of health advocates to be very anti-grain. They point out that people have only been eating grains for 10,000 years and have not evolved the ability to handle them safely. Of course, these same toxins are also found in beans and many other plant foods.
Toxins can be reduced by milling, soaking, sprouting and cooking. One very prominent anti-grain advocate found he needed some carbs to be healthy, but the only grain he'll eat is cooked milled white rice - in which these toxins are minimized.
Fiber in Whole Grains: You've been thoroughly propegandized that "fiber is good", right? Well, unfortunately, that is not entirely so when it comes to grains. The fiber in whole grains is tough and abrasive, made mostly of celulose (wood).
Unlike the "fiber" in many other vegetable foods it is not softened easily and ends up abrading the lining of the digestive tract. This is particularly a problem in "high bran" bread and cerial products. The bran in these products is usually not from grinding whole wheat to fine flour, but is added from stocks produced by the milling insustry.