. A Manual of botany : being an introduction to the study of the structure, physiology, and classification of plants . Botany. FOSSIL PLANTS OF THE CAEBONIFEKOUS SYSTEM. 735 Stigmaria {eTiyfi^a, a mark or impression) is a fossil genus, the species of which abound in the Coal-measures. They occur generally in the bed called the Underclay. Stigmaria ficoides (fig. 914) is the common species. It sends forth grooved and pitted branches, which divide dichotomously, and extend 20 to 30 feet. Slender processes are given off, which appear to have been hollow (fig. 914). These processes (called fistula
. A Manual of botany : being an introduction to the study of the structure, physiology, and classification of plants . Botany. FOSSIL PLANTS OF THE CAEBONIFEKOUS SYSTEM. 735 Stigmaria {eTiyfi^a, a mark or impression) is a fossil genus, the species of which abound in the Coal-measures. They occur generally in the bed called the Underclay. Stigmaria ficoides (fig. 914) is the common species. It sends forth grooved and pitted branches, which divide dichotomously, and extend 20 to 30 feet. Slender processes are given off, which appear to have been hollow (fig. 914). These processes (called fistular roots) form an entangled mass traversing the. Fig. 915. argillaceous lower bed in every direction. In Stigmarias three tissues are met with,—vascular tissue forming the inner part of the cylinder, ligneous forming the wood, and cellular tissue forming a broad cortical zone, as well as the central portion or pith. Stigmaria is apj)arently a thick rhizome, having a large medulla, surrounded by a cylinder of scalariform vessels, and with a mass of cortical parenchyma sur- rounding the whole. Kootlets proceed from the pits on the sides of the rhizome, each containing a small bundle of scalariform vessels having its origin in the vascular cylinder. In the structure of its stem it agrees, according to some, with Oycads, and with certain fleshy Euphorbiacese and Oactacese. According to Williamson, Stig- maria has a pith surrounded by a thick woody zone, containing two distinct sets of primary and secondary medullary rays, the former going direct to the bark. In what are called decorticated stems of the Lepidodendroid plants, the more central axial portion (medulla, wood, and thin layers of inner bark) have disappeared through decay; the bast Fig. 914. Stigmaria flooides; a branch giving off fistular leaves, wliioh traverse the underclay in all directions. Fig. 915. SigiUaria pachyderma; showing fluting of the stem, and the soars of the Please note that these images are ex
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectbotany, bookyear1875
