CHAPTER XXIV 



PHENOGAMS AND CRYPTOGAMS 



316. The plants thus far studied produce flowers; and 

 the flowers produce seeds by means of which the plant 

 is propagated. There are other plants, however, which 

 produce no seeds, and these plants are more numerous 

 than the seed -bearing plants. These plants propagate by 

 means of spores, which are generative cells, usually simple, 

 containing no emhryo. These spores are very small, and 

 sometimes are not visible to the naked eye. 



317. Prominent amongst the spore -propagated plants 

 are ferns. The common Christmas fern (so-called be- 

 cause it remains green during winter) is shown in Fig. 

 304. The plant has no trunk. The leaves spring di- 

 rectly from the ground. The leaves of ferns are called 



fronds. They vary in shape, as 



'V %. ftlh other leaves do. Compare Fig. 



. v^"^ «h- ^ Jfflll "'■^^ ^^^ ^^® pictures in this chap- 



•'v^^^^^^^^^m}. ter. Some of the fronds are seen 



' *■ to be narrower at the top. If 



these are examined more closely 



(Fig. 305) it will be seen that the 



leaflets are contracted and are 



densely covered beneath with 



■^ciA rv, • ♦^.o f^ T^^ t.^ brown bodies. These bodies are 



304. Christmas fern.— Dryoptens 

 acrostichoides ; known also as COllcctioUS of Sporangia Or SpOrC^ 



^''"^'^'^- cases. 



318. The sporangia are collected into little groups, 

 known as sori (singular, sorus) or fruit -dots. Each 

 sorus is covered with a thin scale or shield, known as an 



(172) 



