THE GYMNOSPERMAE : CYCADALES, ETC. 



721 



helps to link Marattiaceae, Cycadales, Bennettitales and Medullosae together 

 into one related plexus. The resemblance to Marattia is increased by 



Fig. 725. — Macrozamia miquelii. Part of 

 a male cone opened to show the 

 microsporangia on the under surface 

 of the sporophylls. 



0>>v 



^6' 



o 



Fig. jzb.—Encephalartos sp. Transverse section of a 

 microsporophyll showing mucilage ducts and micro- 

 sporangia scattered on the lower surface. 



the presence of a zone of indusial hairs arising from the papilla below 



each sorus. , n 1 1 



There may be several hundred sporangia on each sporophyll and several 

 thousand spores in each sporangium, so that the spore output is very large. 

 24 



