9 o GYMNOSPERMAE 



One oi the chief distinctions of this division from the 

 two previous ones, the brvophvtes and pteridophytes, is 

 the absence of an independent sexual generation, the latter 

 being produced directly by the sporophyte as a tissue 

 within the ovule, without the intermediary stage of an 

 independent spore, and remaining in organic connection 

 with it during the sexual process. Both generations, the 

 sexual and asexual, are consequently condensed into one, 

 the nucellar tissue only being the equivalent of the 

 prothallium of the ferns. The new type of plant, which 

 is by analogy a sporophyte but by function a gametophyte, 

 has taken over the production of the sexual cells. 



The pollen is transported by the wind, but in the 

 highest order, Gnetaceae, insect agency has been observed, 

 viz. in JVelwitschia by Pearson and in Ephedra (Mediter- 

 ranean) by Porsch. With regard to Eucep/ialai'tos see 

 that genus. 



All gymnosperms are woody plants. 



THE GENERA OK CYC AD ACE AE. 



(Krom page 96.) 



A. Cones always solitary. Pinnae of leaves with a strong midrib, 



feather-veined. (Plate 14.) 



Endemic. 1. Stangeria Moore 



B. Cones mostly in a whorl. Pinnae of leaves without a midrib, with 



longitudinal parallel veins. (Plate 15.) 

 8 species in S. A., 5 in Trop. Aft. 



2. Encephalartos Lchm. 



