. The elements of botany for beginners and for schools. Botany. oECTION 3.] SEEDLINGS. 17 iiiiiiatioii. The larger the supply to draw upon, the stronger the growth, and the quicker the formation of root below and of stem and leaves above. This deposit of food thickens the cotyledons, and renders them less and less leaf-like in proportion to its amount. 2-i. Examples of Embryos •with thickened Cotyledons. Ill the Pumpkin and Squash (Fig. 2G, 27), the cotyledons are well supplied with nourishing matter, as their sweet taste demonstrates. Still, they are flat and not very thick. In germination th
. The elements of botany for beginners and for schools. Botany. oECTION 3.] SEEDLINGS. 17 iiiiiiatioii. The larger the supply to draw upon, the stronger the growth, and the quicker the formation of root below and of stem and leaves above. This deposit of food thickens the cotyledons, and renders them less and less leaf-like in proportion to its amount. 2-i. Examples of Embryos •with thickened Cotyledons. Ill the Pumpkin and Squash (Fig. 2G, 27), the cotyledons are well supplied with nourishing matter, as their sweet taste demonstrates. Still, they are flat and not very thick. In germination this store is promptly utilized in the devel- opment of the caulicle to twenty or thirty times its length in the seed, and to corresponding thickness, in the formation of a cluster of roots at its lower end, and the early pro- duction of the incipient plumule; also in their own growth into effi- cient green leaves. The case of our common Bern (Pliaseolus vul- garis. Fig. 28-30) is nearly the same, except that the cotyledons are much more gorged; so that, although carried up into the air and light upon the lengthening caulicle, and there acquiring a green color, they never expand into useful leaves. Instead of this, they nourish into rapid growth the plumule, which is plainly visible in the seed, as a pair of incipient leaves; and these form the first actual foliage. 25. Very similar is the germination of the Beech (Fig. 31-33), except that the cauhcle lengthens less, hardly raising the cotyledons out of the ground. Nothing would be gained by elevating them, as they never grow out into efficient leaves; but the joint of stem belonging to the plumule lengthens well, carrying up its pair of real foliage-leaves. 26. It is nearly the same in the Bean of the Old World (Vicia Faba, here called Horse Bean and Windsor Bean) : the caulicle lengthens very little, does not undertake to elevate the heavy seed, which is left below or. Fig. 21. Fruit (one key) of Silver Jlaple, Acer dasycarpu
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Keywords: ., bookpublishernewyorkamericanboo, booksubjectbotany, bookyear1887
