. Nature and development of plants. Botany. DEVELOPMENT OF PLANTS 375 The root is pushed out through the micropyle and bends down into the soil, the hard integument often being cracked open by the swelling of the cells. The cotyledons remain within the seed until they have absorbed all the food from the gametophyte, when they are withdrawn and become erect (Fig. 259).. Fig. 259. Renewal of growth of the embryo. At the left a seed has been cut across to show the relation of parts during the early growth The in- tegument has been ruptured by the swelling of the seed and the protrusion of the roo
. Nature and development of plants. Botany. DEVELOPMENT OF PLANTS 375 The root is pushed out through the micropyle and bends down into the soil, the hard integument often being cracked open by the swelling of the cells. The cotyledons remain within the seed until they have absorbed all the food from the gametophyte, when they are withdrawn and become erect (Fig. 259).. Fig. 259. Renewal of growth of the embryo. At the left a seed has been cut across to show the relation of parts during the early growth The in- tegument has been ruptured by the swelling of the seed and the protrusion of the root which is curving down into the soil. The cotyledons, c, remain in the seed absorbing the food from the gametophyte or endosperm, g. At the right a later growth with the cotyledons partially withdrawn from the seed after the absorption of its food. (e) The Principal Genera of Finales.—The more important genera of Finales may be distinguished as follows: Pinus or pine, leaves long and needle-like, borne in fascicles on short stems that are quite concealed by papery sheathing scales (Fig. 251, i). Larix or larch, short needle-like leaves clustered in tufts on short lateral branches. This is the only northern member of the order with deciduous leaves. Picea or spruce, leaves angled or four- sided, radiating from all sides of stem, petioles remaining on branchlet after leaves fall, thus causing the rough appearance of the branchlets (Fig. 260, 9). Tsuga or hemlock, leaves fiat in two rows, the petiole remaining on the stem after fall of leaf;. 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 Curtis, Carlton Clarence, 1864-1945. New York, H. Holt
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