BEBB WILLOW (_Salix bebbiana_) is nearly always shrubby, but occasionally reaches a trunk diameter of six or eight inches and a height of twenty feet. Its northern limit lies within the Arctic circle, its southern in Pennsylvania, Nebraska, and Arizona. West of Hudson bay it forms almost impenetrable thickets, and in Colorado it ascends mountains to elevations of 10,000 feet. GLAUCOUS WILLOW (_Salix discolor_), commonly known as silver or pussy willow, ranges from Nova Scotia to Manitoba, and southward to Delaware, West Virginia, Indiana, Illinois, and Missouri. It is one of the best known willows within its range, on account of its flowers which are among the earliest of the season, and very showy. The largest specimens are scarcely twenty-five feet high and twelve inches in diameter. MACKENZIE WILLOW (_Salix cordata mackenzieana_) is not abundant, and is one of the smallest of the tree willows. It is nearly always a shrub. Its range extends from California nearly to the Arctic circle, where it occurs in gravelly soil on the borders of mountain streams. MISSOURI WILLOW (_Salix missouriensis_) is so named because it occurs principally in Missouri, but its range extends into Kansas and Iowa. It is occasionally forty feet high and a foot in diameter. It is used for fence posts. BIGELOW WILLOW (_Salix lasiolepis_) is generally called white willow on account of its gray bark. It occurs in California and Arizona, and at its best it is twenty-five feet high and ten inches in diameter. Some use is made of it as fuel, where other wood is scarce. NUTTALL WILLOW (_Salix nuttallii_), called also mountain willow in Montana, ranges from British America, east of the Rocky Mountains, to southern California. Its usual height is twenty or twenty-five feet, and its diameter six or eight inches. In southern California it grows 10,000 feet above sea level. HOOKER WILLOW (_Salix hookeriana_) occurs in the coast region from Vancouver island to southern Oregon, and varies in height from a sprawling shrub to a height of thirty feet and a diameter of one. Little use is made of it. SILKY WILLOW (_Salix sitchensis_), known also as Sitka willow, ranges from Alaska to southern California. The largest specimens are twenty-five feet high and ten inches in diameter. Trunks are largely sapwood and are of little commercial importance. BROADLEAF WILLOW (_Salix amplifolia_), known also as feltleaf willow, was discovered in Alaska in 1899. The leaves are woolly. The largest trees rarely exceed a height of thirty feet and a diameter of six inches. Its range extends to the valley of the Mackenzie river.