92 GYMNOSPERMS 



The vernation, in Cycas, is circinate both in the rachis and the 

 leaflets (fig. 86). In Zantia, Ceratozamia, Boivcnia, and Stangcria the 

 rachis is somewhat circinate (subcircinate) but sometimes looks al- 

 most reflexed. In Dioon, Macrozamia, and Enccphdartos both rachis 

 and leaflets are perfectly straight (fig. 87). In the family, as a whole, 

 there is more of the erect vernation than of the circinate, the pre- 



FiG. 84. — Zamia jloridana: diagram of apex of stem, showing relation of cones, 

 crown, and axis, with the axes much lengthened. — .\fter Dr. F. Grace Smith. '^''s 



vailing type in ferns. It is interesting to note that both Cycadeoidea 

 and Cycadclla have the erect type of vernation. 



The leaves of the various genera are so characteristic that they 

 can be identified by this feature. Sister Mary Alice Lamb"^ con- 

 structed a key based entirely ujion the leaf. Only two genera, Cycas 

 and Stangcria, have a midrib in the leaflet. In Cycas, there is only a 

 midrib without any side veins; while in Stangcria there are side veins 

 from the midrib. Bowcnia has a bipinnate leaf, marking it off easily 

 from all the rest. In Macrozamia there is an obvious gland at the 

 base of the leaflet in most species, and a histological examination 

 might show it in the rest. In Dioon the bases of the leaflets are as 

 wide or even wider than the middle of the leaflet. In Microcycas, the 



