The spruces are pyramidal-shaped trees, with tall and tapering trunks, thickly covered with branches, forming a compact crown. They are widely distributed throughout the cold and temperate regions of the northern hemisphere, where they often form thick forests over extended areas. There are eighteen recognized species of spruce. The Norway spruce has been chosen as a type for this group because it is so commonly planted in the northeastern part of the United States. The hemlock is represented by seven species, confined to temperate North America, Japan, and Central and Western China. [Illustration: FIG. 7.--The Norway Spruce.] How to tell them from each other: The needles and branches of the spruce are _coarse_; those of the hemlock are _flat and graceful_. The individual leaves of the spruce, Fig. 9, are four-sided and green or blue on the under side, while those of the hemlock, Fig. 10, are flat and are _marked by two white lines_ on the under side. THE NORWAY SPRUCE (_Picea excelsa_) Distinguishing characters: The characteristic appearance of the full-grown tree is due to the *drooping branchlets* carried on *main branches which bend upward* (Fig. 7). Leaf: The leaves are dark green in color and are _arranged spirally_, thus making the twigs coarser to the touch than the twigs of the hemlock or fir. In cross-section, the individual leaflet is quadrilateral, while that of the pine is triangular. Form and size: A large tree with a straight, undivided trunk and a well-shaped, conical crown (Fig. 7). Range: Northern Europe, Asia, northern North America. Soil and location: Grows in cool, moist situations. Enemies: The foliage of the spruce is sometimes affected by _red spider_, but is apt to be more seriously injured by drought, wind, and late frosts. Value for planting: Commonly planted as an ornamental tree and for hedges. It does well for this purpose in a cool northern climate, but in the vicinity of New York City and further south it does not do as well, losing its lower branches at an early age, and becoming generally scraggly in appearance. [Illustration: FIG. 8.--A Group of Hemlock.] Commercial value: The wood is light and soft and is used for construction timber, paper pulp, and fuel. Other characters: The _fruit_ is a large slender cone, four to seven inches long. Comparisons: The _white spruce_ (_Picea canadensis_) may be told from the Norway spruce by the whitish color on the under side of its leaves and the unpleasant, pungent odor emitted from the needles when bruised. The cones of the white spruce, about two inches long, are shorter than these of the Norway spruce, but are longer than those of the black spruce.