It covers large areas in various parts of northern North America and grows to its largest size in Manitoba. The black spruce has little value as an ornamental tree.
The Colorado blue spruce (Picea parryana or Picea pungens) which is commonly used as an ornamental tree on lawns and in parks, can be told from the other spruces by its pale-blue or sage-green color and its sharp-pointed, coarse-feeling twigs. Its small size and sharp-pointed conical form are also characteristic.
It grows to a large size in Colorado and the Middle West. In the Eastern States and in northern Europe where it is planted as an ornamental tree, it is usually much smaller.
Fig. 9.—Twig of the Norway Spruce.
Hemlock (Tsuga canadensis)
Distinguishing characters: Its leaves are arranged in flat layers, giving a flat, horizontal and graceful appearance to the whole branch ([Fig. 8]). The individual leaves are dark green above, lighter colored below, and are marked by two white lines on the under side ([Fig. 10]).
The leaves are arranged on little stalks, a characteristic that does not appear in the other evergreen trees.
Form and size: A large tree with a broad-based pyramidal head, and a trunk conspicuously tapering toward the apex. The branches extend almost to the ground.