TYPES OF CRYPTOGAMS; PTERIDOPHYTES 291 



356. Reproduction in Ferns. The reproduction of ferns 

 is a more interesting illustration of alternation of gen- 

 erations than is afforded by mosses. The sexual plant, 

 gametophyte, is the minute prothallium, and the non- 

 sexual plant, sporophyte, which we commonly call the 

 fern, is merely an outgrowth from the fertilized egg-cell, 

 and physiologically no more important than the sporophyte 

 of a moss, except that it supplies its own food instead of 

 living parasitically. Like this sporophyte, the fern is an 

 organism for the production of vegetative spores, from 

 which new plants endowed with reproductive apparatus 

 may grow. 



THE STUDY OF A CLUB-MOSS (LYCOPODIUM} 



357. Occurrence. Several species of Lycopodium are common in 

 rich woods in the northern and mountainous portions of the eastern 

 United States. Any species may be studied. 



358. Examination. Note whether the plant is chiefly erect or 

 prostrate and vine-like. Describe the mode of branching. Are the 

 leaves arranged flat-wise or equally on all sides of the stem ? Describe 

 the leaves briefly. Are they all of one kind or do some portions of 

 the plant evidently have smaller leaves? 



Select fruiting specimens and determine the position of the spo- 

 rangia. Is the leaf, near whose base each sporangium is situated, like 

 the ordinary foliage leaves of the plant ? Are the fruiting portions 

 of the plant similar in general aspect or different from the rest of 

 the plant and raised above it on stalks ? Examine the spores. Are 

 they all of one kind ? 



If Selaginella is used in place of Lycopodium or for comparison, 

 two kinds of sporangia are to be sought, differing chiefly in shape. 

 Describe each briefly. Compare the number of spores in each. The 

 larger spores (macrospores) germinate and at length produce pro- 

 thallia bearing archegonia, while the smaller produce prothallia 

 bearing antheridia. The archegonia, after fertilization, develop each 



