. The elements of botany for beginners and for schools. Botany. SECTION 17.] PTERIDOPHYTES. 161 like cavities, and fertilize the cell. This thereupon sets up a growth, forms a vegetable bud, and so develops the new plant. 491. An essentially similar process of fertilization has been discovered in the preceding and the foUovcing families of Pteridophytes; but it is mostly subterranean and very difficult to observe. 493. Club-Mosses or Lycopodiums. Some of the common kinds, called Ground Pine, are familiar, being largely used for Christmas wreaths and other decoration. They are low evergreens, s
. The elements of botany for beginners and for schools. Botany. SECTION 17.] PTERIDOPHYTES. 161 like cavities, and fertilize the cell. This thereupon sets up a growth, forms a vegetable bud, and so develops the new plant. 491. An essentially similar process of fertilization has been discovered in the preceding and the foUovcing families of Pteridophytes; but it is mostly subterranean and very difficult to observe. 493. Club-Mosses or Lycopodiums. Some of the common kinds, called Ground Pine, are familiar, being largely used for Christmas wreaths and other decoration. They are low evergreens, some creeping, all with considerable wood in their stems: this thickly beset witti small leaves. In the axils of sokc of these leaves, or more commonly, in the axils of pecu- liar leaves changed into bracts (as in Fig. 511, 512) spore-cases appear, as roundish or kidney-shaped bodies, of firm texture, opening round the top into two valves, and discharging a great quantity of a very fine yellow powder, the spores. 493. The Selaginellas have been separated from Lycopodium, which they much resemble, because they produce two kinds of spores, in sepa- rate spore-cases. One kind (Microspores) is just that of Lycopodium; the other consists of only four large spores (Macro- spores), in a spore-case which usually breaks in pieces at maturity (Eig. 513-515). 494. The Quillworts, Isoetes (Fig. 516-519), are very unlike Club Mos- ses in aspect, but have been associated with them. They look more like Rushes, and live in water, or partly out of it. A very short stem, like a corm, bears a cluster of roots underneath; above it is covered by the broad bases of a cluster of awl- shaped or thread-shaped leaves. The spore-cases are immersed in the bases of the leaves. The outer leaf-bases contain numerous macrospores; the inner are filled with innu- merable microspores. 495. The Pillworts {Maisilia and Pilidana) are low aquatics, wliich. Fig. 520. Plant of Marsilia quadrifoliata, reduced in size; a
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Keywords: ., bookpublishernewyorkamericanboo, booksubjectbotany, bookyear1887
