A practical course in botany : with especial reference to its bearings on agriculture, economics, and sanitation . ter part oftheir surface is in contact with water and can absorb directlywhat is needed. Land plants will often develop water roots and thrivefor a time if the liquid holds in solution a sufficient quantityof air and mineral nutrients. Place a cutting of wanderingJew in a glass of clear water, and in from four to six days itwill develop beautiful water roots in which both hairs andcap are clearly visible to the naked eye. 85. Haustoria, from a Latin word meaning to drain,or exhaus
A practical course in botany : with especial reference to its bearings on agriculture, economics, and sanitation . ter part oftheir surface is in contact with water and can absorb directlywhat is needed. Land plants will often develop water roots and thrivefor a time if the liquid holds in solution a sufficient quantityof air and mineral nutrients. Place a cutting of wanderingJew in a glass of clear water, and in from four to six days itwill develop beautiful water roots in which both hairs andcap are clearly visible to the naked eye. 85. Haustoria, from a Latin word meaning to drain,or exhaust, is a name given to the roots of parasitic plants,or such as live by attaching themselves to some other livingorganism, from which they draw their nourishment readymade. Their roots are adapted to penetrating the sub-stance of the host, as their victim is called, and absorbingthe sap from it. Dodder and mistletoe are the best-known 76 PRArTTCAL rOTRSE IN BOTANY examples of plant parasites, though the latter is only partiallyparasitic, as it merely takes up the sap from the host and manufactures its own food. U A B Fig. 88.—Beech root: A, grown inunsterilized wood humus: p, strands offungal hypha;, associated at a, withhumus; B, grown in wood humus freedfrom fungus by sterihzation — it is notprovided with fungal hyphse, and hasroot hairs, li. (A and B both severaltimes magnified.) by means of its green Saprophytes. — Akinto parasites are saprophytes,which live on dead and decay-ing vegetable matter. Theyare only partially parasiticand do not bear the haustoriaof true parasites. Many ofthem, of which the Indianpipe (Monotropa) and coralroot are familiar examples,obtain their nourishment inpart, at least, by association with certain saprophytic fungi,which enmesh their roots in a growth of threadlike fibersthat take the place of root hairs and absorb organic foodfrom the rich humus inw^hich these plants growths are calledmycorrJiiza, meaning fungal roo
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