Leaf blades are broadly lance-shaped to oval, to 8 cm (3.1 in) long, the margins finely toothed and lined with tiny round glands.

[5][6] Salix tweedyi is native to western North America, from British Columbia south and east through parts of Washington, Idaho and Montana to Wyoming.

[7][6] It grows in subalpine and alpine zones along streams and lakes; in marshes and bogs; on talus slopes, tundra, quartzite, granite and sometimes limestone; at 1,400–4,000 m (4,600–13,100 ft) elevation.

As Rose noted, "His collecting was merely incidental to his other work, and was done chiefly while reaching some mountain peak or returning from it to camp.

[1] In his 1905 "Notes on American Willows", Carleton Roy Ball reported that Tweedy's type specimen was not the first collection of Salix tweedyi.

In the US National Herbarium, Ball discovered a specimen of S. tweedyi collected by John Merle Coulter, expedition botanist on the Hayden Survey of 1872—two decades before Tweedy found it in the Bighorn Mountains.

][3] Thomas Conrad Porter, also a botanist on Hayden's 1872 expedition, identified Coulter's collection as Salix barrattiana.