332 



THE PTERIDOPHYTES 



bodies (Fig. 288) generally subterranean and practically desti- 

 tute of chlorophyll, like those of 

 the moonwort and adder' s-tongue. 

 They are therefore saprophytic,and 

 associated with them are fungal 

 filaments to form a mycorrhizal 

 relation (Sec. 278). The sexual 

 organs are sunken structures. 

 The sperms are two-ciliate. A 



The embryo sporophyte remains 

 attached to the gametophyte by a 

 large foot (Fig. 288) for a long 

 time after the stem and root are 

 developed, and must obtain much 

 nourishment from the gameto- 

 phyte, as in the case of the ferns. 



323. Selaginella. Selaginclla 

 is readily distinguished from Lyco- 

 podium. The leaves in most 

 species are arranged in four rows, 

 two rows of smaller leaves on the 

 upper surface and two rows of 

 larger leaves somewhat at the sides 

 (Fig. 289, A). The cones also have 

 four rows of spore leaves (sporo- 

 phylls) and are consequently four- 



FIG. 288. Gametophytes and ang i ec i. The spores are of two 

 young sporophytes of a club moss . , . 



(Lycopodium complanatum) sizes > and the tyP 6 1S P^hapS the 



A, gametophyte with young sporo- best ^lustration of heterospory in 



phyte: /, tissue filled with the fiia- the pteridophytes. Forms of Scl- 



ments of a fungus situated iust 77 ,-> n^j 



outside a layer of palisade cells. W 1 "* are frequently Called 



B, the fungus-infected tissue, c, Httle club mosses," for many of 



a young club moss still attached ., i T j-i 



to the subterranean gametophyte. them are much more delicate than 



-A, B, from material of Bruch- the lycopods. *But Some tropical 

 mann prepared by Miss Lyon ; ,,. j 



C, after Bruchmann species, frequently cultivated in 



