. Botany for high schools and colleges. Botany. Pig. 866.—Prothalllum and young plant of Adi- antum CapUlus-Veneris, seen in vertical longitudinal section. ^,^, the prothallium ; a, archegonia : h, root- hair ; E, the young plant; w, its first root; 6, its first leaf. X about 10.—After Sachs. 490.—The Pilicinse may be here arranged iiiider four orders, as follows :* /. IsosporecB.— Spores of one kind. Order 1. rilioes, the true Ferns. Sporangia compos- ed of modified tri- cViomes, each de- veloped from a sin- gle epidermal cell, prodnced in clusters on the surface of or- dinary or slightly mod
. Botany for high schools and colleges. Botany. Pig. 866.—Prothalllum and young plant of Adi- antum CapUlus-Veneris, seen in vertical longitudinal section. ^,^, the prothallium ; a, archegonia : h, root- hair ; E, the young plant; w, its first root; 6, its first leaf. X about 10.—After Sachs. 490.—The Pilicinse may be here arranged iiiider four orders, as follows :* /. IsosporecB.— Spores of one kind. Order 1. rilioes, the true Ferns. Sporangia compos- ed of modified tri- cViomes, each de- veloped from a sin- gle epidermal cell, prodnced in clusters on the surface of or- dinary or slightly modified leaves. Each sporangium with an elastic ring. No stip- ules. Order 2. Marattiaeese, the Eingless Ferns. Sporangia produced from a group of epi- dermal cells; the ring either rudimentary or wanting. The large, much-branched leaves with stipules. Order 3. Ophioglossacese, the Adder-Tongues. Sporan- gia formed by groups of cells in the interior of a modified branch of the sheathing leaf. The ring is absent. //. HeterosporecB. — Spores of two kinds. Order 4. Rhizocarpese, the Pepperworts. Sporangia com- posed of modified trich- omes (?); the microsporangia containing many Fig. 257.—A, a transverse section of the stem (rhizome) of Pteris aquUina, slightly enlarged, r, brown sclerenchy- ma, forming a hard c heath beneath the epidermis ; p, colorless parenchyma of the fundamental system ; ig, inner fibro- vascular bundles; Off, the broad upper band of the outer bundle zone; pr, a band of elongated thick-walled cells, sclerenchyma or fibrous tissue—a second one occurs on the other side of the cen- tral bundles. S, the separated .upper fibro-vnscular bundle of tne stem (rhi- zome), St, and its branches, si', «<"; ft, bundles of the leaf stalk ; «, «, u, out- line of the stem.—After Sachs. * This arrangement is essentially that modification of Saclis' pro- posed by Professor McNab. See his " Outlines of the Classification of Plants,&quo
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbotany, bookyear1885
