File:The structure and development of mosses and ferns (Archegoniatae) (1918) (14784662052).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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ively large and may be producedin great numbers, this being especially conspicuous in A.fiisiformis, where they may reach a length of six or sevencentimetres, and- stand so close together that a patch of fruit-ing plants looks like a tuft of fine grass. Both of the common Calif ornian species, A. Pearsoni andA. fusiformis are perennial. The growing point of the shoot,with a certain amount of the adjacent tissue, remains alive andpersists through the summer, after the rest of the plant hasdried up. Probably the great amount of mucilage in thethallus helps to check the loss of water, and enables the plantto survive the long summer drought. Growth begins promptly with the first autumn rains, andby mid-winter, or sometimes earlier, the reproductive organsmature. The sporophyte continues to grow in length as longas the thallus receives the necessary moisture. New sporog-enous tissues develops at the base of the sporophyte long afterthe first spores have been shed. With the cessation of its
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IV. THE ANTHOCEROTES 125 water-supply through the drying up of the thallus, the sporo-phyte finahy dies. In order to study the apical growth satisfactorily, youngplants that show no signs of the sporogonia should be selected.In A. fusiformis such a plant will show the margin of thethallus occupied by numerous growing points separated by agreater or smaller numljer of intervening cells. It is some-what difficult to determine positively whether one or moreapical cells are present. In sections parallel to the surface theinitial cells are seen to occupy the bottom of a shallow depres-sion (Fig. 65, C). In the case figured, x probably is the singleapical cell, and it seems likely that this is usually the case, al-though Leitgeb was inclined to think that there were severalmarginal cells of equal rank. The outer wall of the cellsshows a very marked cuticle. A vertical section passingthrough one of the growing points (Fig. 66) shows that theapical cell is much larger than appears from the ho

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