348 



GENERAL MORPHOLOGY OF PLANTS 



appressed into a tuft so that they protect the egg cases and young 

 fruit body. At the base of the stem are numerous thread-like 

 rhizoids usually brownish in color. In the moss Mnium, the 

 male plants are also shorter than the female ones, and the leaves 

 at the apex of the stem form a rosette. There are 

 also prostrate stems with two rows of lateral prom- 

 inent leaves, the third row on the underside 

 being rudimentary.* 



500. The sexual organs. The 

 sperm cases (antheridia) are crowded 

 at the apex of the male plant, and 

 intermingled with peculiar club- 

 shaped bodies (paraphyses) which 

 contain chlorophyll. The sperm case 

 is more broadly clavate, and consists 

 of a wall of a single layer of cells 

 containing the sperm cells. When 

 the sperms are mature the sperm 

 case is ruptured at the apex by the 

 pressure resulting from the absorp- 



Fig. 308, 

 Female plant 

 (gametophyte) of 

 a moss (Mnium), 

 showing rhizoids 

 below, and the 

 tuft of leaves 

 above which pro- 

 tect the arche- 

 gonia. 



Fig. 309. 

 Male plant 

 (gametophyte) of 

 a moss (Mnium), 

 showing rhizoids 

 below and the 



antheridia at the tion of water, and the mass of sperm 



center above sur- 

 rounded by the cells escapes. 



rosette of leaves. 



The sperms uncoil and 

 swim about until some finally reach 

 the egg case. They are long and slender with two long cilia at 

 the smaller end. The egg cases (archegonla) are borne in 

 groups on the end of the female plant. An egg case is flask- 

 shaped, with a short stalk which lifts the base a little distance 

 from the end of the shoot. The base is called the venter, 

 and the slender portion the neck. A canal is formed in the 

 neck at maturity by the dissolving of the central row of cells, 

 which leads into the venter. In the venter is the egg. 



501. The moss fruit (sporogonium) . The moss fruit con- 

 sists of a capsule supported on a slender stalk. In the hairy-cap 

 moss this capsule is a short, four-angled structure, at first covered 



* Such a stem is dorsiventral, and resembles the stems of the foliose liverworts 

 which are also dorsiventral. In the moss Fissidens all the stems are dorsiventral. 



