. The elements of botany for beginners and for schools. Botany. SECTION 17.] BRYOPHYTES. 1G5 and very lijgrometric threads (called Elaters) which are thought to aid ia the dispersiou of the spores. (Eig. 542-54:1.) 502. Marchautia, the commonest and largest of the true Liverworts, forms large green plates or fronds on damp and shady ground, and sends up from some part of the upper face a stout stalk, ending in a several-lobed umbrella-shaped body, under the lobes of which hang several thin-walled spore-cases, wliicb burst open and discharge spores and elaters. Riccia natans (Fig. 545) consists
. The elements of botany for beginners and for schools. Botany. SECTION 17.] BRYOPHYTES. 1G5 and very lijgrometric threads (called Elaters) which are thought to aid ia the dispersiou of the spores. (Eig. 542-54:1.) 502. Marchautia, the commonest and largest of the true Liverworts, forms large green plates or fronds on damp and shady ground, and sends up from some part of the upper face a stout stalk, ending in a several-lobed umbrella-shaped body, under the lobes of which hang several thin-walled spore-cases, wliicb burst open and discharge spores and elaters. Riccia natans (Fig. 545) consists of wedge-shaped or heart-shaped fronds, which float free in pools of still water. The under face bears copious rootlets; iu the substance of the upper face are the spore-cases, their pointed tips. merely projecting: there they burst open, and discharge their spores. These are comparatively few and large, and are in fours; so they are very like the macrospores of Pillworts or Quillworts. 503. Thallophyta, or Thallophytes in Euglisii form. This is the name for the lower class of Cellular Cryptogams, — plants in which there is no marked distinction into root, stem, and leaves. Roots in any proper sense they never have, as organs for absorbing, although some of the larger Seaweeds (such as the Sea Colander, Fig. 553) have tliem as holdfasts, Instead of axis and foliage, there is a stratum of frond, in such plants commonly called a Thallus (by a strained use of a Greek and Latin word which means a green shoot or bough), which may have any kind of form, leaf-like, stem-like, branchy, extended to a flat plate, or gathered into a sphere, or drawn out into threads, or reduced to a single row of cells, or even reduced to single cells. Indeed, Thallophytes are so multifarious, so numerous in kinds, so protean in their stages and transformations, so re- condite in their fructification, and many so microscopic in size, either of Fig. 542. Fructification of a Jungermannia, magnified; its
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Keywords: ., bookpublishernewyorkamericanboo, booksubjectbotany, bookyear1887
