Like _P. resinosa_ and _P. Banksiana_, it has its foliage leaves in twos, with neither of which, however, is it likely to be confounded; aside from the habit, which is quite different, it may be distinguished from the former by the shortness of its leaves, which are less than 2 inches long, while those of _P. resinosa_ are 5 or 6; and from the latter by the position of its cones, which point outward and downward at maturity, while those of _P. Banksiana_ follow the direction of the twig. Picea nigra, Link. _Picea Mariana, B. S. P. (including Picea brevifolia, Peck)._ BLACK SPRUCE. SWAMP SPRUCE. DOUBLE SPRUCE. WATER SPRUCE. =Habitat and Range.=--Swamps, sphagnum bogs, shores of rivers and ponds, wet, rocky hillsides; not uncommon, especially northward, on dry uplands and mountain slopes. Labrador, Newfoundland, and Nova Scotia, westward beyond the Rocky mountains, extending northward along the tributaries of the Yukon in Alaska. Maine,--common throughout, covering extensive areas almost to the exclusion of other trees in the central and northern sections, occasional on the top of Katahdin (5215 feet); New Hampshire and Vermont,--common in sphagnum swamps of low and high altitudes; the dwarf form, var. _semi-prostrata_, occurs on the summit of Mt. Mansfield (_Flora of Vermont_, 1900); Massachusetts,--frequent; Rhode Island,--not reported; Connecticut,--rare; on north shore of Spectacle ponds in Kent (Litchfield county), at an elevation of 1200 feet; Newton (Fairfield county), a few scattered trees in a swamp at an altitude of 400 feet: (New Haven county) a few small trees at Bethany; at Middlebury abundant in a swamp of five acres (E. B. Harger, _Rhodora_, II, 126). South along the mountains to North Carolina and Tennessee; west through the northern tier of states to Minnesota. =Habit.=--In New England, usually a small, slender tree, 10-30 feet high and 5-8 inches in diameter; attaining northward and westward much greater dimensions; reduced at high elevation to a shrub or dwarf tree, 2 or 3 feet high; trunk tapering very slowly, forming a narrow-based, conical, more or less irregular head; branches rather short, scarcely whorled, horizontal or more frequently declining with an upward tendency at the ends, often growing in open swamps almost to the ground, the lowest prostrate, sometimes rooting at their tips and sending up shoots; spray stiff and rather slender; foliage dark bluish-green or glaucous. This tree often begins to blossom after attaining a height of 2-5 feet, the terminal cones each season remaining persistent at the base of the branches, sometimes for many years. =Bark.=--Bark of trunk grayish-brown, separating into rather close, thin scales; branchlets roughened with the footstalks of the fallen leaves; twigs in autumn dull reddish-brown with a minute, erect, pale, rusty pubescence, or nearly smooth.