. Botany; principles and problems. Botany. Fig. 200.—Transverse section (diagrammatic) of the stem of a fern {Adian- tum). The fibrovascular system is here arranged in a hollow tube, the wood surrounded by bast both within and without. At the right, a segment of the cylinder is passing off to a leaf as a leaf-trace, causing a temporary break, or leaf- gap, in the cylinder. Wood black, bast dotted. summit. The fern stem lacks a cambium, and the secondary wood and bast so common in the seed plants are consequently absent. The fibro-vascular system may occasionally be a solid. Fig. 201.—Fern spor
. Botany; principles and problems. Botany. Fig. 200.—Transverse section (diagrammatic) of the stem of a fern {Adian- tum). The fibrovascular system is here arranged in a hollow tube, the wood surrounded by bast both within and without. At the right, a segment of the cylinder is passing off to a leaf as a leaf-trace, causing a temporary break, or leaf- gap, in the cylinder. Wood black, bast dotted. summit. The fern stem lacks a cambium, and the secondary wood and bast so common in the seed plants are consequently absent. The fibro-vascular system may occasionally be a solid. Fig. 201.—Fern sporangia of various types. The ring of heavy-walled cells is the annulus, by the contraction of which the wall of the sporangium is ruptured at maturity and its spores scattered. {From Strasburgcr). axis, but is connnonly a i-ing or tube surrountling a central pith (Fig. 200) and is often broken up by gaps into a series of sei)arate bundles. The bast here occurs not only on 1h(> outside of 1h(>. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Sinnott, Edmund Ware, 1888-. New York, McGraw-Hill
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectbotany, bookyear1923
