[Illustration: FIG. 131.--A MUSHROOM, example of a saprophytic plant. This is the edible cultivated mushroom.] _All plants with naturally white or blanched parts are dependent._ Their leaves do not develop. They live on organic matter--that which has been made by a plant or elaborated by an animal. The dodder, Indian pipe, beech drop, coral root among flower-bearing plants, also mushrooms and other fungi (Figs. 131, 132) are examples. The dodder is common in swales, being conspicuous late in the season from its thread-like yellow or orange stems spreading over the herbage of other plants. One kind attacks alfalfa and is a bad pest. The seeds germinate in the spring, but as soon as the twining stem attaches itself to another plant, the dodder dies away at the base and becomes wholly dependent. It produces flowers in clusters and seeds itself freely (Fig. 133). [Illustration: FIG. 132.--A PARASITIC FUNGUS, magnified. The mycelium, or vegetative part, is shown by the dotted-shaded parts ramifying in the leaf tissue. The rounded haustoria projecting into the cells are also shown. The long fruiting parts of the fungus hang from the under surface of the leaf.] =Parasites and Saprophytes.=--A plant that is dependent on a living plant or animal is a =parasite=, and the plant or animal on which it lives is the =host=. The dodder is a true parasite; so are the rusts, mildews, and other fungi that attack leaves and shoots and injure them. The threads of a parasitic fungus usually creep through the intercellular spaces in the leaf or stem and send suckers (or haustoria) into the cells (Fig. 132). The threads (or the hyphæ) clog the air-spaces of the leaf and often plug the stomates, and they also appropriate and disorganize the cell fluids; _thus they injure or kill their host_. The mass of hyphæ of a fungus is called =mycelium=. Some of the hyphæ finally grow out of the leaf and produce spores or reproductive cells that answer the purpose of seeds in distributing the plant (_b_, Fig. 132). [Illustration: FIG. 133.--DODDER IN FRUIT.] A plant that lives on dead or decaying matter is a =saprophyte=. Mushrooms (Fig. 131) are examples; they live on the decaying matter in the soil. Mold on bread and cheese is an example. Lay a piece of moist bread on a plate and invert a tumbler over it. In a few days it will be moldy. The spores were in the air, or perhaps they had already fallen on the bread but had not had opportunity to grow. Most green plants are unable to make any direct use of the humus or vegetable mold in the soil, for they are not saprophytic. The shelf-fungi (Fig. 134) are saprophytes. They are common on logs and trees. Some of them are perhaps partially parasitic, extending the mycelium into the wood of the living tree and causing it to become black-hearted (Fig. 134). [Illustration: FIG. 134.--TINDER FUNGUS (_Polyporus igniarius_) on beech log. The external part of the fungus is shown below; the heart-rot injury above.]