66 



The Hemlocks 



The wood is soft, brittle, and weak, coarse-grained, not durable, light reddish 

 brown; its specific gravity is about 0.42. It is extensively used in carpentry, 

 especially for frame-work in the regions of its greatest abundance. The bark is 

 largely used in taiming leather, being the most important substance so used in 

 North America. It is also occasionally employed in medicine for its astringent 

 properties. An oleoresin obtained from the wood and bark is called Canada 

 pitch, and the volatile oil distilled from the leaves is used as a curative agent. 



As an ornamental tree the Canadian hemlock has long been a favorite in the 

 northern States and Canada. The principal objection to it is its slow growth. 



2. CAROLE^A HEMLOCK — Tsnga caroliniana Engebnann 



This Hemlock, also called Crag hemlock, Southern hemlock, and Hemlock, 

 is a rather local tree, being found on the rocky slopes and stream banks of the 



Blue Ridge Moimtains of Virginia, the 

 Carolinas, and northeastern Georgia. It 

 is rarely abundant, but grows among the 

 Canadian hemlock. White pine, and vari- 

 ous deciduous trees. It reaches a maxi- 

 mum height of 25 meters, with a trunk 

 diameter of i meter. 



The branches are stout, relatively 

 short, the lower pendulous, forming a 

 compact cone; the bark is 2 to 2.5 cm. 

 thick, fissured into broad, flat, obliquely 

 confluent ridges and broken into thin 

 close scales of a red-brown color; the 

 slender twigs are orange-brown, and 

 covered with short dark hairs, becoming 

 smooth and dull brown with age. The 

 winter buds are blunt, dark red-brown, 

 their scales somewhat hairy. The leaves 

 are linear, 1.5 to 2 cm. long, i mm. wide, 

 rounded or notched at the end, grooved, dark green and shining above, hght 

 green, with numerous stomata, and revolute-margined beneath; they persist for 

 about five years. The staminate flowers are ovoid, 3 mm. long, of a purplish 

 color. The pistillate flowers are also purplish. The cones are oblong, 3 to 3.5 

 cm. long, short-stalked and dull brown when ripe; the scales are oblong, 2 cm. 

 long, half as wide, thin, concave, rounded at the apex, abruptly narrowed at the 

 base, slightly grooved and minutely hairy on the outer surface, finally spreading 

 widely from the axis of the cone; the bracts are small, rounded or truncate at the 

 apex, wedge-shaped at the base; the ovoid seed is 4 nun. long and covered by 

 resin cells; the wing is about four times the length of the seed. 



Fig. 52. — Carolina Hemlock. 



