. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. VIII MARATTIALES 291 ever, bath of Marattia and Angiopteris, there is but a single axial bundle, as in the petiole of the cotyledon. Fig. 167, B shows a cross-section of a pinnule from a large leaf of A. evecta, which has much the same structure as that of Marattia. The central vascular bundle is horse-shoe shaped in section, and shows a central mass of large tracheids with retic- ulate or scalariform markings, surrounded by the phloem made up of very large sieve-tubes much like those of Botry
. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. VIII MARATTIALES 291 ever, bath of Marattia and Angiopteris, there is but a single axial bundle, as in the petiole of the cotyledon. Fig. 167, B shows a cross-section of a pinnule from a large leaf of A. evecta, which has much the same structure as that of Marattia. The central vascular bundle is horse-shoe shaped in section, and shows a central mass of large tracheids with retic- ulate or scalariform markings, surrounded by the phloem made up of very large sieve-tubes much like those of Botrychium, and with these are the ordinary protophloem cells and bast parenchyma. A distinct bundle-sheath is absent, as, according to Holle, it is from all the bundles in both Marattia and An- giopteris, except those of the larger roots. The bulk of the. Fig. i63.^A, Section of a large root of Angiopteris evecta, X14; m, mucilage duct; B, part of the central cylinder, X about 70; en, endodermis. ground tissue is composed of large parenchyma cells, but on both sides just below the epidermis is a band of colourless cells which resemble exactly the collenchyma of Phanerogams. In the base of the petiole this becomes harder and forms a colour- less sclerenchyma, which in Dancea is replaced by brown scleren- chyma like that of the true Ferns. In the lamina of the leaf in Angiopteris too, the arrangement of the tissues is strikingly like that of the typical Angiosperms. A highly-developed palisade parenchyma occupies the upper part of the leaf beneath the epi- dermis, which bears stomata only on the lower side of the leaf. The rest of the mesophyll is composed of the spongy green parenchyma found in the other Ferns. The smaller veins both here and in Marattia have collateral 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 o
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Keywords: ., bookauthorcampbelldouglashought, bookcentury1900, bookdecade1910
