. A practical course in botany, with especial reference to its bearings on agriculture, economics, and sanitation. Botany. 76 PRACTICAL COURSE IN BOTANY. c B Fig. 88. — Beech root: A, grown in unsterilized wood humus: p, strands of fungal hyphse, associated at a, with humus ; B, grown in wood humus freed from fungus by sterilization — it is not provided with fungal hyphae, and has root hairs, h. (A and B both several times magnified.) examples of plant parasites, though the latter is only partially parasitic, as it merely takes up the sap from the host and manufactures its own food by means of
. A practical course in botany, with especial reference to its bearings on agriculture, economics, and sanitation. Botany. 76 PRACTICAL COURSE IN BOTANY. c B Fig. 88. — Beech root: A, grown in unsterilized wood humus: p, strands of fungal hyphse, associated at a, with humus ; B, grown in wood humus freed from fungus by sterilization — it is not provided with fungal hyphae, and has root hairs, h. (A and B both several times magnified.) examples of plant parasites, though the latter is only partially parasitic, as it merely takes up the sap from the host and manufactures its own food by means of its green leaves. 86. Saprophytes. — Akin to parasites are saprophytes, which live on dead and decay- ing vegetable matter. They are only partially parasitic and do not bear the haustoria of true parasites. Many of them, of which the Indian pipe (Monotropa) and coral root are familiar examples, obtain their nourishment in part, at least, by association with certain saprophytic fungi, which enmesh their roots in a growth of threadlike fibers that take the place of root hairs and absorb organic food from the rich humus in which these plants grow. Such growths are called mycorrhiza, meaning "fungal ; Similar associations are formed by some of the higher plants also. The root- lets of the common beech and of certain of the pine family, for instance, are often enveloped in a network of fungus fi- bers, and in this case root hairs are developed very poorly, or not at all. Besides greatly increasing the absorbent surface by their ramification through the soil, the mycorrhizal threads may possibly benefit the plant in other ways also, as,. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Andrews, Eliza Frances, b. 1840; Lloyd, Francis Ernest, 1868-1947. ed. New York, Cincinnati [etc. ] American
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