The trend toward using natural foods, to living off the land to eating wild plants may lead people to try strange plants as foods. Don't do it, says Dr. Richard A. Howard, director of the Arnold Arboretum of Harvard University.

Although adults obviously are vulnerable, he says, our primary concern is with the inquisitive child. Relatively small amounts of potentially toxic material are all that's necessary to cause severe or even fatal consequences in a small body, whereas the same volume might have little or no effect on a teen-ager or adults.

Howard has prepared some safety rules:

Avoid eating plants that have milky or colored juices, including members of the millweed poison ivy, spurge and poppy families.

Exceptions: The young shoots of the millweed plants are edible, and even lettuce has a milky juice.

Avoid all unknown white or red fruits. Poison ivy, poison sumac and some species rasberry have white fruits and are poisonous. The majority of unrecognized red fruits are potentially toxic.

Avoid eating wild seeds, for the seed of the plant usually has the greatest accumulation of chemical that may be toxic. In general the toxicity of plants is greatest in the storage organs of seeds, fruits, nuts and tubers.

Young plants of young fruits may be less toxic than the same parts in mature condition. However, some plant poisons are breakdown products, and wilted leaves may often be more dangerous than fresh material.

Avoid all fruits that are three-angled or three-lobed involving the spurge, soapberry, [WORD ILLEGIBLE] amaryllis and lily families.

Avoid all bulbs that lack the smell of onions or garlic. Some members of the lily and amaryllis and related families with basal bulbs can cause death.

If it is absolutely necessary to eat unknown plant materials, cook the plant parts in two changes of water. Then sample a small portion. If the cooked material tastes unpleasant, don't eat it.

Many plant poisons are water-soluble or destroyed by heat. Cooking and discarding two changes of water can lessen the amount of poisonous material or remove it completely.

If poisoning is suspected, act immediately. Some plant poisons cause an immediate reaction, others a delayed one.

Residents of cities that have poison centers or large botanical gardens can get information from either source.Look under "Poison" in the emergency pages of the telephone book.

Before you call, have a piece of the plant available so you can give a description.