. Introduction to structural and systematic botany, and vegetable physiology. Botany. THE BOOT. 79 has only one cotyledon or true seed-leaf (Fig. 128, &c.); the other leaves, if any are appai-ent, are enclosed by the cotyledon and be- long to the plumule; and the embryo with one cotyledon is ac- cordingly termed Monocotyledonous. The difference in tliis respect coincides with striking differences in the structure of the stems, leaves, and blossoms, and lays a foundation for the division of Flowering or Phasnogamous plants (114) into two great Classes. 129. In a few plants, such as Pines, t
. Introduction to structural and systematic botany, and vegetable physiology. Botany. THE BOOT. 79 has only one cotyledon or true seed-leaf (Fig. 128, &c.); the other leaves, if any are appai-ent, are enclosed by the cotyledon and be- long to the plumule; and the embryo with one cotyledon is ac- cordingly termed Monocotyledonous. The difference in tliis respect coincides with striking differences in the structure of the stems, leaves, and blossoms, and lays a foundation for the division of Flowering or Phasnogamous plants (114) into two great Classes. 129. In a few plants, such as Pines, the embryo is provided with from three to ten cotyledons, which expand into a circle of as many green leaves in gei-mination (Fig. 133, 134) : such an embryo is said to be Polycotyledonous, i. e. of many cotyledons. 130. Having talcen this general survey of the development of PhiEnogamous plants from the seed, and of their common plan of growth, their further development and their morphology may best be studied by examining in succession the three universal organs of vegetation (116) of which they all consist, viz. the Root, Stem, and CHAPTER III. OP THE ROOT, OB DESCENDING AXIS. 131. The Root is the descending axis (120), or that portion of the body of the plant which grows downwards, ordinarily fixing the vegetable to the soil and absorbing nourishment from it. As already mentioned (121), the root grows in length by continual additions of new fabric to its lower extremity, elongating from that part only or chiefly; so that the tip of a growing root always consists of the most newly formed and active tissue. It begins, in germination, at the root-end of the radicle. That only this extremity of the radicle is root is evident from the mode in which the radicle grows, namely. FIG 133. Section of a seed of a Pine, with its embryo of several cotyledons. 134. Early seedling Fine, with Us stemlet, displaying its six Please note that these images are extracted fr
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