. Botany for high schools and colleges. Botany. 112 BOTANY. the bundles are curiously isolated from the surrounding ground tissues of the stem. 141.—The bundle of the nearly related Lycopodium com- planatum is much more complex in its structure (Fig. 101). Here there are four parallel plates of tracheary tissue, each having a structure like the single plate of the bundle of Selaginella incequifolia. Between the tracheary plates there is in each case a row of sieve tubes imbedded in a lignified tissue composed of elongated cells (sclerenchyma, or fibrous. Fig. 101.—Crose-eection of the stem of
. Botany for high schools and colleges. Botany. 112 BOTANY. the bundles are curiously isolated from the surrounding ground tissues of the stem. 141.—The bundle of the nearly related Lycopodium com- planatum is much more complex in its structure (Fig. 101). Here there are four parallel plates of tracheary tissue, each having a structure like the single plate of the bundle of Selaginella incequifolia. Between the tracheary plates there is in each case a row of sieve tubes imbedded in a lignified tissue composed of elongated cells (sclerenchyma, or fibrous. Fig. 101.—Crose-eection of the stem of Lycopodivm comj^anntnm. The flbro-vaa- cular bundle is composed of four plates or trachf ary ti-ene (darlcer in the figure), between which of lignified tissue composed of elongated cells ; each of these latter masses encltjses a row of sieve tubes (larger and thicker walled in the figure); the bundle sheath is seen to bound on its iunersideathickniassof very thick walled fibrous tissue; exterior to this (toward B) is a layer of chlorophyll-bearing parenchyma, bounded by a well-devfloped epidermis. The small vessels at the ex- treme edges of the plates of tracheaiy titjsue are narrow and spirally marked ; the remainder of each plate is composed of scalariform vessels. X 100.—After Sachs. tissue?). Around this central fibro-vascular portion there is a layer of parenchyma, and outside of this a bundle sheath, which is commonly regarded as marking the boundary of the bundle ; it is doubtful, however, whether it should be so considered, as exterior to it lies a thick mass of fibrous tissue which completely envelops all the previously described tissues.* * Sachs ("Text-Book," p. 418) rejrards the stem of Lycopodium as composed of four united bundles and compares them to the separate bundles of Selaginella. Do Bary (" Anatomie," etc., p. 363), on the. Please note that these images are extracted from scanned page images that may have been digitally
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbotany, bookyear1885
