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 usually simple generative cells 

 containing no embryo. 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 

 other leaves do. Compare Fig. 

 125 and the pictures in this chap- 

 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 



304. Christmas fern.-Dryopteris bl>OWn b dieS ' TheS6 b dieS ar6 

 acrostichoides; known also as collections of Sporangia Or Spore- 



Aspldium ' 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) 



