. 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. 34 BOOTS. [section 5. 68. Contrast between Stem and Root. Stems are ascending axes; roots are descending axes. Stems grow by the successive development of interjiodes (13), one after another, each leaf-bearing at its summit (or node); so that it is of the essen- tial natiire of a stem to bear leaves. Roots bear no leaves, are not distinguishable into nodes and inter- nodes, but grow on continuously from the lower end. They
. 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. 34 BOOTS. [section 5. 68. Contrast between Stem and Root. Stems are ascending axes; roots are descending axes. Stems grow by the successive development of interjiodes (13), one after another, each leaf-bearing at its summit (or node); so that it is of the essen- tial natiire of a stem to bear leaves. Roots bear no leaves, are not distinguishable into nodes and inter- nodes, but grow on continuously from the lower end. They commonly branch freely, but not from any fixed points nor iii definite order. 69. Although roots generally do not give rise to stems, and there- fore do not propagate the plant, exceptions are not uncommon. For as stems may produce ad- ventitious buds, so also may roots. The roots of the Sweet Potato among herbs, and of the Osage Orange among trees freely produce adventi- tious buds, developing into leafy sliouts; and so these plants are propagated by root-cut- tings. But most growths of subterranean origin which pass for roots are forms of stems, the common Potato for example. 70. Roots of ordinary kinds and uses may be roughly classed \xAo fibrous sxAfieshy. 71. Fibrous Roots, such as those of Indian Corn (Pig. 70), of most annuals, and of many perennials, serve only for absorption -. these are slender or thread-like. Pine roots of this kind, and the flue branches which most roots send out are called Rooilets. 72. The whole surface of a root absorbs moisture from the soil while fresh and new; and the newer roots and rootlets are, the more freely do they im- bibe. Accordingly, as long as the plant grows above ground, and expands fresh fohage, from which moisture largely escapes into the air, so long it continues to extend and multiply its roots in the soil beneath, renewing and increasing the fresh surface for absorbing moisture, in proportion to the demand from above. And wh
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