The structure & development of the mosses and ferns (Archegoniatae) . the lamina isstill very small. The youngspike now forms a beak-shapedbody curving inward and up-ward, and sections of slightlyolder stages than the onefigured show the first indicationsof the developing still the base of the leafbecomes narrowed into the petiole, and the spike also becomes divided into the uppersporiferous portion and the short slender pedicel. The anatomical structure of the leaf is extremely epidermis is composed of rather thick-walled cells, irregularlypolygonal in outline, with
The structure & development of the mosses and ferns (Archegoniatae) . the lamina isstill very small. The youngspike now forms a beak-shapedbody curving inward and up-ward, and sections of slightlyolder stages than the onefigured show the first indicationsof the developing still the base of the leafbecomes narrowed into the petiole, and the spike also becomes divided into the uppersporiferous portion and the short slender pedicel. The anatomical structure of the leaf is extremely epidermis is composed of rather thick-walled cells, irregularlypolygonal in outline, with large stomata at intervals, about whichthe cells are arranged concentrically, and frequently with a gooddeal of regularity. The stomata themselves (Fig. 116), seenfrom above, have an angular outline, but from below are perfectlyoval, and cross-sections show that this appearance is due to apartial overarching of the guard cells of the stoma by thesurrounding epidermal cells. The upper walls of the guardcells are thickened irregularly, giving them the appearance of. Fig. 116.—Stoma from the leaf of Ophioglossuinpendtibim, x 260. 234 MOSSES AND FERNS CHAP. being folded longitudinally. There is no distinct hypodermaformed, and the bulk of the leaf is made up of a uniform meso-phyll composed of nearly globular cells with much chlorophyll,and separated by numerous intercellular spaces. In the petiolethe tissues are similar, but more compact, and the walls of theground tissue are all deeply pitted. The vascular bundles arenearly circular in section and show a compact mass of trachearytissue (Fig. i 17, /), surrounded by nearly uniform cells with
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Keywords: ., bookcentury1800, bookdecade1890, bookidstructuredev, bookyear1895
