. Gray's school and field book of botany. Consisting of "Lessons in botany," and "Field, forest, and garden botany," bound in one volume. Botany; Botany. SECTION 5.] ROOTS. 37 upon the tranks or limbs of other plants; by the latter because, having no couuection -with tbe soil, they mast derive their sustenance from the air only. They have aerial roots, which do not reach the ground, but are used to fix the plant to the surface upon which the plant grows: they also take a part in absorbing moisture from the air. 80. Parasitic Plants, of which there are various kinds, strike
. Gray's school and field book of botany. Consisting of "Lessons in botany," and "Field, forest, and garden botany," bound in one volume. Botany; Botany. SECTION 5.] ROOTS. 37 upon the tranks or limbs of other plants; by the latter because, having no couuection -with tbe soil, they mast derive their sustenance from the air only. They have aerial roots, which do not reach the ground, but are used to fix the plant to the surface upon which the plant grows: they also take a part in absorbing moisture from the air. 80. Parasitic Plants, of which there are various kinds, strike their roots, or what answer to roots, into the tissue of foster plants, or form at- tachments with their surface, so as to prey upon their juices. Of this sort is the Mislletoe, the seed of which germinates on the bough where it falls or is left by birds; and the forming root penetrates the bark and en- grafts itself into the wood, to which it becomes united as firnjly as a natural branch to its parent stem ; aud indeed the parasite lives just as if it were a branch of the tree it grows and feeds on. A most common |)arasilic herb is the Dodder; which abounds in low grounds in summer, and coils its long and slender, leafless, yellowish stems — resembling tangled threads of yarn — round and round the stalks of other plants; wherever they touch piercing the bark with minute and very short rootlets in the form of suckers, which draw out the nourishing juices of the plants laid hold of. Other parasitic plants, like the Beech-drops and Pine-sap, fasten their roots under ground upon the roots of neighboring plants, and rob them of their juices. 81. Some plants are partly parasitic; while most of their roots act in the ordinary way, others make suckers at their tips which grow fast to the. roots of other plants and rob them of nourishment. Some of our species of Gerardia do this (Fig. 89). 82. There are phanerogamous plants, like Monotropa or Indian Pipe, the roots of which feed ma
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