The Vascular Structure of the Sporophylls 
of the Cycadaceae 1 . 
BY 
W. C. WORSDELL, F.L.S. 
With Plates XVII and XVIII. 
NE of the most marked characters of the plants com- 
prising the order Cycadaceae is the sympodial nature 
of the development of the stem, whereby the main axis 
usually terminates in a peduncle bearing a cone with sporo- 
phylls, while the vegetative axis is continued as a lateral 
branch. An exception, however, is found in the female 
plant of Cycas, where sympodial branching does not obtain, 
the vegetative axis growing continuously through ; here the 
sporophylls, instead of being borne on differentiated portions 
of the axis known as cones, occur in whorls intercalated 
amongst the ordinary foliage-leaves of the stem. 
The structure of the peduncle in this order has recently 
been described 2 , and has been found to possess certain 
structures not known in the vegetative axis, such as the 
primary concentric strands in the cortex and in the central 
1 From the Jodrell Laboratory, Royal Gardens, Kew. 
2 Scott, Ann. Bot., Vol. xi, 1897. 
[Annals of Botany, Vol. XII. No. XL VI. June, 1898. 1 
