XVI GENERA. 



scales, the outer two of which are short and abortive, 

 and the inner two larger and fertile. 



Seeds in twos or threes under each of the fertile 

 scales, almost round and amply three-winged. 



Gen. Biota, Don. Leaves scale-like, very small, in opposite 

 pairs, flattened, and imbricated in four rows. 



Flowers, male and female on the same plant, but 

 separate. 



Cones roundish, squarrose, leathery, and composed of 

 from six to eight valves or scales, in opposite pairs, pel- 

 tated on the top. 



Seeds in twos under each scale, crustaceous and wing- 

 less. 



Gen. Thuiopsis, Siebold. Leaves scale-formed, opposite, regu- 

 larly and closely imbricated in four rows. 



Flowers, male and female on the same plant, but 

 separate. 



Cones somewhat globular, woody, and composed of 

 eight or ten valvated, smooth scales. 



Seeds in fives, at the base of each scale, orbicularly 

 compressed, and furnished with a membranaceous wing 

 on each side. 



Gen. Thuja, Linnceus. Leaves in opposite pairs, compressed, 

 very small, scale-formed, imbricated, and mostly unequal 

 in size. 



Flowers, male and female on the same plant, but 

 separate. 



Cones ovate-oblong, terminal, leathery, with from four 

 to six scales, in opposite pairs, and unequal in size. 



Seeds in twos at the base of each scale, and furnished 

 with transparent wings. 



Gen. Libocedrus, Endlicher. Leaves scale-formed, in opposite 

 pairs, and imbricated, in four rows, the upper and under 

 ones being much the smallest. 



Flowers, male and female on the same plant, but 

 separate. 



