234 



PLANT LIFE. 



always occurs when they are unequal. A corresponding dif- 

 ference in size is often found between the sporangia con- 

 taining small spores (inicrosporangia) and those containing 

 large spores (megasporangia} (figs. 241, 242). 



The sex terms, male and female, applicable primarily to 

 the sex cells, are applied also to the organs and to the plants 



FIG. 240. 



FIG. 241. 



FIG. 240. Sporophyte of a club-moss {Lycopodiitm clavatum). The horizontal stem 

 is densely covered with leaves ; those on the erect branch become small and few for a 

 space ; these are succeeded by broader leaves, the sporophylls, crowded in a dense 

 spike, j. Half natural size. After Prantl. 



FIG. 241. Section through three sori of an aquatic fernwort (Salvinia. natans). 

 Each is covered by a double indusium. /, /', two sori consisting of sporangia con- 

 taining microspores isee fig. 242); , a sorus consisting of sporangia, each containing 

 one megaspore. Magnified 10 diam. After Sachs. 



which bear them, so that the microspores are said to produce 

 male plants, and the megaspores female plants. For a fur- 

 ther account of the gametophyte, see *\\ 386, 394, 393. 



328. Seed plants. In the seed plants this differentiation 

 of the spores is always found. The microspores are called 



