192 Postelsia 
or on leading shoots all four ranks simular, 
slightly carinate, with spreading tips. Flowers 
monoecious, minute. Staminate flower consist- 
ing of two or three pairs of decussate stamens 
borne on a short axis; stamens peltate, anther 
sacs two to four, longitudinally dehiscent.  Pis- 
tillate flower of four to six pairs of decussate, 
erect, oblong scales, the central or lower ones 
fertile, each bearing at its base two to four erect 
orthotropous ovules. Fruit ripening the first 
season, woody or leathery; cone-scales oblong, 
with a small boss on the back near the tip, the 
fertile scales largest, each bearing one to four 
seeds. 
Four species, two of North America and two 
of eastern Asia. Only the following occurs in 
western North America. 
Thuja plicata D. Don. “ex Lambeniyekau 
1824. Cedar. 
A large tree with short horizontal branches 
often pendulous at the extremities, distichous 
branchlets and deciduous spray; leaves 2-6 milli- 
meters long, scale-like, usually acute, eglandular 
or conspicuously glandular, dimorphic on all 
