. Botany for agricultural students . Botany. COLEOCHAETE 313 tion the oospore forms four zoospores, each of which develops a new filament. In some forms of Oedogonium there are both male and female filaments. In some species the male plants are miniature filaments and attach themselves to the female plants, where they produce sperms in their terminal cells. Coleochaete. — This form {Fig. 269), found growing attached to water plants, has a disk-shaped plant body and also presents some new features in connection with its reproduction. Like Oedogonium it reproduces by zoospores and sexually by oo
. Botany for agricultural students . Botany. COLEOCHAETE 313 tion the oospore forms four zoospores, each of which develops a new filament. In some forms of Oedogonium there are both male and female filaments. In some species the male plants are miniature filaments and attach themselves to the female plants, where they produce sperms in their terminal cells. Coleochaete. — This form {Fig. 269), found growing attached to water plants, has a disk-shaped plant body and also presents some new features in connection with its reproduction. Like Oedogonium it reproduces by zoospores and sexually by oospores. One of the new features is the development of a case around the oospore by the adjacent cells. This fea- ture suggests a close rela- tionship of this form to the higher Algae, where the formation of a case around the immediate product of the oospore is a prevalent feature. The second new feature is that the oospore upon germination develops neither a plant nor zo- ospores, but a structure consisting of several cells each of which develops a zoospore from which a new plant arises. Thus between fertihzation and the de-. FiG. 269. — Coleochaete scutala. A, the plate-like plant body with two oogonia developed (X 25); B, thick-walled oospore surrounded by vegetative cells (much en- larged) ; C, a much enlarged section through the oospore and its jacket of sterile cells, showing the multicellular body produced by the oospore, each cell of which pro- duces a zoospore. Redrawn from WoUe, Atkinson, and Altmanns. velopment of new plants, there is introduced a new structural stage and one that is char- acteristic of higher plants. These new features with others have led to the theory that the higher plants have evolved from Algae of the type of Coleochaete. In having multicellular plant bodies and more advanced methods of reproduction, the Confervales, as a group, show advancement over the-preceding groups. The plant body is a simple filament, branched filament, or a disk-shap
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1919
