368 



GENERAL MORPHOLOGY OF PLANTS 



532. Cycas. In cycas the small spore-bearing leaves (micro- 

 sporophylls) are flattened leaves with true sporangia, similar to 

 the spore cases of some of the ferns, scattered over the under 



Fig. 364- 

 Macrosporangiumof Cycas revoluta. 



Fig. 365- 



Roentgen photograph of same, show- 

 ing female prothallium. 





surface of the leaves. These contain the small spores (micro- 

 spores) (fig. 362). The female plants have the large spore- 

 bearing leaves (macrosporophylls, or megasporophylls) . These 



are produced at certain seasons in 

 a rosette near the apex of the stem. 

 Each spore-bearing leaf is shaped 

 like the ordinary leaves, with numer- 

 ous pinnate divisions, but they are 

 much smaller, lack chlorophyll, and 

 Fig. 366. are very hairy or woolly with pale 



sinl^^ie'at^eilUlulLwTnTthe yellowish brown hairs. The large 



spore cases (macrosporangia) , or 



ovules, are borne on either side of the leaf near the base, one each 

 in place of a pinna. When they are ripe they resemble a 

 stone fruit with a fleshy exocarp, a stony endocarp, and the 

 meat or kernel within is the female prothallium or endo- 

 sperm (fig. 365). 



