CHAPTER XIV. THE SPERM APHYTA. 



367 



being borne on different individuals. Both kinds are borne at 

 the apex of the stem, the staminate ones consisting of leaves 

 modified into shield-shaped scales compactly arranged on a 

 short axis, in much the same way as in the spike-like fructifica- 

 tion of Equisetum. Each scale bears on its under surface 

 numerous pollen sacs or microsporangia, which are usually col- 

 lected into groups of from two to five each. See Fig. 569, B. 

 The staminal leaves differ from those of most other flowering- 

 plants, in becoming hard and woody, and persisting for a long 

 time. 



Fig. 569. — A, carpellary leaf of Cycas revoluta, about one-fourth natural size, a, one 

 of the pinna; of the leaf; o, o, ovules developed in the place of pinnae. B, one of the anther- 

 bearing scales from a staminate cone of Zamia, oce of the Cycads; fi, pollen-sacs. C, one 

 of the carpellary scales from the fertile cone of Zamia, showing two ovules, oz>, ov, pendent 

 from the under surface. 



The female flower is also, except in the genus Cycas, spike- 

 like or cone-like in appearance, the cones often being of large 

 size and made up of peltate scales, on the under surface of each 

 of which two ovules or macrosporangia are borne. See Fig. 

 569, C. The ovules are orthotropous, and each consists of a 

 nucellus enclosed in a single thick coat which, at maturity, 

 becomes succulent. They are of large size, the largest in the 

 vegetable kingdom, attaining, in some species, the size of a 



