GENERA. Xvii 



Cones oval, more or less obtuse, leathery, and com- 

 posed of from four to six scales, which are but slightly 

 concave on the inner face, and with the lower ones 

 much the smallest. 



Seeds singly or in twos under each scale, and unequally 

 two- winged. 



Gen. Callitris, Ventenat. Leaves very small, scale-formed, in 

 alternate opposite pairs, close at the base of the joints, 

 and with a gland on the back. 



Flowers, male and female on the same plant, but 

 separate. 



Cones globular, or somewhat four-sided, and composed 

 of four valved woody scales truncated at the top, and 

 with the alternate pair smallest. 



Seeds, one or two at the base of each scale, slightly 

 compressed, or three-edged, and winged on each side. 



Gen. Frenela, Mirbel. Leaves mostly ternate, scale-formed, and 

 decurrent. 



Flowers, male and female on the same plant, but 

 separate. 



Cones globular or conical, and formed of six valvated 

 scales, the alternate ones being much the smallest. 



Seeds numerous under each scale, more or less angular, 

 and laterally winged. 



Gen. Widdringtonia, Endliclier. Leaves alternate, or in whorls, 

 linear or needle-shaped, and spreading on the branches, 

 but very small, scale-formed, and somewhat imbricated, 

 with a gland on the back, in the adult branchlets. 



Flowers, male and female on the same plant. 



Cones globular, and composed of four valves or scales, 

 somewhat in a whorl, round a depressed axis, and con- 

 verging at the sides. 



Seeds few, from abortion, and mostly in twos ; but 

 with from five to ten ovules at the base of each scale, in 

 one or two series, with a crustaceous covering, spreading 

 on each side into membranaceous wings. 



