PLANT WORLD CONTINUED 



Fig. 121. 



A., a leaflet of the frond viewed from be- 

 low to show the position of the sori. B., de- 

 tails of the sori and veining on a portion of a 

 leaflet. C., section of a sorus ; t., indusium ; 

 a., sporangia. D., a spore case or sporangium, 

 snowing the opening from which the spores 

 (sp.) have been discharged; r., ring. (From 

 Bergen & Davis' "Principles of Botany," by 

 permission of Ginn and Co., Publishers.) 



and this is the beginning of the root-like bodies, the rhizoids, which are 

 to hold the plant in place and absorb moisture and food material from 

 the ground. 



This minute plant developing 

 from the spore is called the prothal- 

 lium ( ). It is 



often heart-shaped with a portion 

 just posterior to the notch called 

 the cushion, several cells thick, and 

 the outer part called the wings 

 which are only one cell in thickness. 

 Near the notch of the heart, 

 close to the cushion, several flask- 

 shaped bodies, the archegonia are 

 formed. Each archegonium contains 

 an egg cell. Among the rhizoids 

 are the sperm gonads called anthe- 

 ridia ( ). Many tiny motile 



cells are found in the antheridia at 

 maturity, but as these are dis- 

 charged and find a small amount of 

 moisture they reach the egg and 

 fertilize it. 



It will thus be seen that here, too, as in the mosses, there is an alter- 

 nation of generations, the ordinary Fern being the asexual plant and 

 the prothallus the sexual. 



SPERMATOPHYTES 



This group includes the plants which bear flowers like the rose and 

 lily, as well as such flowerless groups as the pines which have their re- 

 productive organs in cones or clusters, and are by no means so conspicu- 

 ous as are those contained in a real flower. 



Two older groupings of these higher plants are : 

 Phanerogams ( ). (The flowering plants.) 



Cryptogams ( ). (The non-flowering plants.) 



This grouping is one that came into existence before the sexual 

 processes of plants had been studied to any extent, and so is not accu- 

 rate, because the so-called hidden processes of the Cryptogams is in 

 reality more evident than those of the complicated Phanerogams. As 

 the seed is the all-important part of a plant from the reproductive point 

 of view, the name spermatophyte has become popular. Seed plants, like 

 Ferns, are sporophytes, though there is a gametophyte generation in 

 their life-history, but it is so reduced in structure that it is quite difficult 

 to see. The seed must, therefore, be studied. 



It can readily be understood that the seed having a hard covering, 

 which is wonderfully adapted for a protective purpose, lends itself well 



