File:The structure and development of mosses and ferns (Archegoniatae) (1918) (14804975393).jpg

Identifier: structuredevelop00camp3 (find matches)
Title: The structure and development of mosses and ferns (Archegoniatae)
Year: 1918 (1910s)
Authors: Campbell, Douglas Houghton, 1859-1953
Subjects:
Publisher: New York, Macmillan
Contributing Library: The LuEsther T Mertz Library, the New York Botanical Garden
Digitizing Sponsor: The LuEsther T Mertz Library, the New York Botanical Garden

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s of the leaf are bestfollowed in the smallerspecies. Prantl ((7), p.155) describes it as fol-lows for O. Liisitanicum,and states that it is essen-tially the same in otherspecies. The primarybundle given off from thestem branches just after itenters the petiole. Themain bundle gives off twosmaller lateral branchesright and left. The latterbranch again near the baseof the sporangiophore,andthe upper branches fromeach unite to form the sin-gle bundle that enters thelatter. The sporangia aresunk in the tissue of thesporophyll, and scarcelyproject at all above thesurface, where the positionof each one is indicatedby a faint transverse fur-row which marks theplace where it opens.Seen in sections parallel tothe flat surface these ap-pear perfectly round, but .^in transverse section are^kidney-shaped (Fig.140, C). The apex of the stem forms a blunt cone, which, however, isnot visible from the outside. A longitudinal section throughthe end of the stem shows that it is covered by a sheath com-
Text Appearing After Image:
FiG. 1^2.^0phioglossum vulgaUim, X i. 24« MOSSES AND FERNS CHAP. posed of several layers of cells, and this encloses a cavity inwhich are the growing point of the stem and the youngest leaf.The leaves here form much more rapidly than in the species ofthe temperate regions, as the growth continues uninterruptedlythroughout the year. The real apex of the stem forms an in-clined nearly plane surface, slightly raised in the centre, wherethe single apical cell is placed (Fig.i34,A,B). This cell is by nomeans conspicuous, and not always readily found, but probably is always present. It hasthe form of an invertedthree-sided pyramid, but thelateral faces are more or lessstrongly convex, and theapex may be truncate. Fromthe few cases observed it isnot possible to say whetherin addition to the three setsof lateral segments basal seg-ments are also formed, but itis by no means impossiblethat such is the case. Ac-cording to investigations ofRostowzew ((i), p. 451),the apical cell of the stemof O

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