. The natural history of plants, their forms, growth, reproduction, and distribution;. Botany. 716 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM. By the elongation of this suspensor the embryo proper is brought down into the aforementioned food-reserve, where it continues its development. This process is quite similar to the corresponding stage in Flowering Plants, where the suspensor is almost universally found. LepidodendracecB.—This family, represented only by fossils from the Devonian and Carboniferous formations, consisted of large-growing Lycopod-like forms, with huge stems clad with linear
. The natural history of plants, their forms, growth, reproduction, and distribution;. Botany. 716 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM. By the elongation of this suspensor the embryo proper is brought down into the aforementioned food-reserve, where it continues its development. This process is quite similar to the corresponding stage in Flowering Plants, where the suspensor is almost universally found. LepidodendracecB.—This family, represented only by fossils from the Devonian and Carboniferous formations, consisted of large-growing Lycopod-like forms, with huge stems clad with linear leaves. They exhibit a secondary growth in thickness (wanting in recent Lycopods), and both micro- and macrospores were produced in the cones. Casts of Lepidodendron-stems bear characteristic rhomboidal areas corresponding to the leaf bases, a,nd upon these the actual leaf-scars may be Fig. 405.—Lycopodiales. 1 IsoBtes lacustris. 2 Expanded fcase of leaf showing tlie sporangium immersed in its socket and partly hidden by the velum and the ligule above, s Longitudinal section of base of leaf showing the strands crossing the sporangium and the inser- tion of the ligule. * Leaf from the cone of Lycopodium davatum showing the kidney-shaped sporangium, s A single 3pore of L. davatum. 6 Prothallium of L. annotinum with young plant attached, i natural size; 2, »_ 4^ 6 x 10; s x 100. (After Luerssen.) SigillariacecB.—Another family which flourished in carboniferous times. Like the LepidodendraeesB, their stems are gigantic, thickened and scarred; they were also heterosporous. The marks on the stems are not rhomboidal, but shield-like, and they stand in vertical rows. The curious branching remains named Stigmaria constitute the root (or rhizome) of Sigillaria. Isoetacece.—Is a small family of aquatic mode of life, containing the single genus Isoetes, which is represented by some 50 species in various portions of the globe. Unlike the other members of the alliance Lycopod
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectbotany, bookyear1895
