DEVELOPMENT OF PLANTS 329 



up numerous, erect branches and giving off roots that branch 

 with great regularity. Various species of Lycopodium are ex- 

 tensively gathered for decorations since the aerial portions of 

 the stems are thickly clothed with small moss-like leaves. The 

 second genus of the family {Phylloglossum) contains but one 

 species, which is found in New Zealand and Australia. It is of 

 interest because it is the most simple fern known (Fig. 238), 

 consisting of a few narrow leaves, rudimentary strobilus and 

 poorly developed tissues. 



The sporangia of the Lycopodiaceae are large considering the 

 size of the leaf, and usually appear on specialized leaves that are 

 arranged in strobili on the ends of erect branches (Fig. 239). 

 The sporangia open by a longitudinal cleft and the spores are 

 produced in such quantities in some of the forms that they are 

 of commercial importance, being used for flashlight effects and 

 sold as lycopodium powder. 



{a) The Gametophyte of the Lycopodiaceae. — The most in- 

 teresting feature about the club moss ferns is the sexual genera- 

 tion, because it indicates that these ferns may have been derived 

 from the same ancestry as the mosses or at least from a very 

 primitive stock. In certain species the spores produce a rather 

 cylindrical erect gametophyte which terminates in a number of 

 radially-arranged green leaf-like lobes, among which the arche- 

 gonia and antheridia are produced (Fig. 240). This structure 

 has been compared to a miniature leafy moss plant. This sug- 

 gestion of relationship is strengthened by the resemblance of the 

 male gametes to those of the mosses, the sperms, so far as they 

 have been observed, being small, almost straight bodies, and pro- 

 vided with two cilia (Fig. 240). The archegonia may also be 

 more primitive than those of the ferns in possessing several neck 

 canal cells and five instead of four rows of neck cells. The gameto- 

 phyte appears in all species examined to be associated with 

 symbiotic fungi, as in Ophioglossales, and this has led in many 

 forms to its subterranean and chlorophylless development. 



(b) The Germination of the Gametospore. — The germination of 

 the gametospore is characterized by new departures that will 

 continue on through the seed plants. The gametospore enlarges 



