6o4 



STRUCTURE AND LIFE HISTORIES 



structural characters of Cycadeoidea are shown in Figs. 

 421-427. 



In Cycadeoidea dacotensis the ''flower," which in some 

 specimens was 5 inches long, was a strobilus, consisting of 

 a thick axis on the lower part of which were numerous 

 bracts arranged in spirals. The bracts surrounded a 



P'v 



m^^mmmm: 



Fig. 425. — Cycadeoidea Wielandi. Longitudinal section through the 

 axis of a female inflorescence, or cone. Z, old leaf-base; d, insertion of 

 disc; s, erect seed, borne at summit of seed-pedicle inserted on convex 

 receptacle; b, hair-covered bract. (After Wieland.) 



campanula of about 20 stamens. Each stamen was, in 

 reality, a pinnately compound sporophyll, about 4 inches 

 long, rolled in toward the center of the flower, and 

 bearing two rows of compound microsporangia (pollen- 

 sacs) on each leaflet. They thus closely resembled the 

 sporophyll of a fern. 



