ENUMERATION OF CONIFERS 265 



P. japonica, Beiss. (Tsuga japonica, Shiras.). Tree to 100 feet tall; branch- 

 lets glabrous, pale yellowish-gray: leaves more or less directed forward, often 

 slightly curved, emarginate, |-1 inch long, lustrous bright green above: 

 cone ovoid, 1^4-2 inches long; bracts exserted and reflexed. Japan. — Intro- 

 duced in 1898 to Europe and a year later to this country, but at the Arnold 

 Arboretum the species did not prove hardy. 



P. sinensis, Dode. Related to P. japonica: tall tree; branclilets brown, 

 pubescent: leaves to 13^^ inches long, emarginate, more or less pectinately 

 arranged: cones to 2)^ inches long, with puberulous scales and upright or 

 reflexed bracts. Western China. — Introduced to France in 1912 and in 

 1914 to the Arnold Arboretum where it did not prove hardy. Pseudotsuga 

 Wilsoniana, Hayata, from Formosa, and P. Forrestii, Craib, from Yunnan, 

 are probably not different from P. sinensis. 



23. TSUGA, Carr. HEMLOCK 



Evergreen trees with slender horizontal branches and cinnamon-red 

 furrowed bark; winter-buds minute, not resinous: leaves usually 2-ranked, 

 short-petioled, linear, flat or angular, falling away in drying: staminate 

 flowers axillary, subglobose; ovule-bearing flowers termmal, the scales about 

 as long as the bracts, each with 2 ovules at the base: cones small, ovate, or 

 oblong with thin flexible persistent scales, much longer than the bracts; 

 seeds winged; cotyledons 3-6. (Tsuga is the Japanese name of the genus.) — 

 Nine species in temperate North America, Japan, western China, and on 

 the eastern Himalayas. The genus is closely allied to Abies and Picea and 

 differs little in the structure of the flowers; the cones are very similar to those 

 of the larch, but the leaves, which are much like those of Abies in their 

 outward appearance, though smaller, are very different in their internal 

 structure from all allied genera, having a solitary resin-duct situated in the 

 middle of the leaf below the fibro-vascular bundle. 



Tsuga should be called "hemlock spruce," but in common speech it is 

 usually alluded to as "hemlock." The "hemlock" of the ancients is a poison- 

 ous umbelliferous herb {Conium maculatum). 



A. Leaves with 2 white lines beneath, grooved above, much flattened, 

 distinctly 2-ranked: cones }^-l3^ inches long. (Eutsuga, 

 Engelm.). 

 B. Margin of leaves entire; apex of leaves usually emarginate, 

 sometimes obtuse. 



c. Branchlets glabrous, grayish- or yellowish-browTi 1. T. Sieboldii 



cc. Branchlets pubescent. 



D. Length of leaves J 3- J 2 inch, emarginate at apex: branch- 

 lets pubescent throughout, reddish-brown 2. T. divcrsifolia 



DD, Length of leaves J^^-1 inch: branchlets yellowish-brown 

 or gray, pubescent chiefly in the grooves. 



