The willows which are very largely represented throughout the region, in the low or moist ground and banks of streams, as shrubs or small trees; or on the drier slopes, and in alpine meadows and summits, frequently as very diminutive shrubs with stems less than an inch high, have been omitted entirely, owing to the extreme difficulty of distinguishing between them in a work of this kind. BETULACEÆ _Birch Family_ Trees or shrubs with alternate simple leaves; staminate and pistillate flowers borne in separate catkins on the same plant; the staminate usually long, slender, and drooping; the pistillate short and erect; fruit cone-like. [Sidenote: =Betula papyrifera= Marsh. _Paper Birch, Canoe Birch._] Becoming a large forest tree; bark chalky white, peeling in thin layers. Leaves ovate, acute, or acuminate, dentate and denticulate, smooth above, glandular and hairy on the veins beneath, slender-petioled 1½—4 inches long. Staminate catkins 2—4 inches long; pistillate catkins ¾ of an inch or more long. Sparingly on the slopes in the vicinity of Field, British Columbia; not a common tree. [Sidenote: =Betula occidentalis= Hook. _Western Red Birch._] A tree sometimes 100 feet high but much smaller in our region; the bark smooth dark bronze; twigs gray-brown, warty. Leaves broadly ovate or nearly orbicular, sharply serrate, short-petioled, smooth on both sides or sparingly hairy beneath ¾—2 inches long. On river shores throughout the region, sparingly from Field west. [Sidenote: =Betula glandulosa= Michx. _Glandular Birch, Scrub Birch._] A shrub 1—8 feet with brown, glandular, warty twigs. Leaves orbicular, oval or ovate, smooth, rounded at the apex, crenate-dentate, bright green above, pale and sticky, glandular-dotted beneath, short petioled, ¼—1 inch long. Staminate catkins, commonly solitary, about ½ an inch long; cones when ripe ½—1 inch long. In moist ground and thickets in the lower valleys through the Rockies, frequent. [Sidenote: =Alnus tenuifolia= Nutt. _Slender-leaved Alder._] A shrub 4—20 feet high with brown bark. Leaves more or less broadly ovate, 2—3 inches long, acute, rounded or slightly heart-shaped at the base, acutely doubly toothed, light green and smooth on both sides or slightly hairy. Staminate catkins slender, drooping, 1—2 inches long; fruiting cones erect, ½ an inch or less long. In moist places and thickets and stream banks at the higher elevations throughout the region, very abundant in the Selkirks. LORANTHACEÆ _Mistletoe Family_ Parasitic herbs growing on woody plants and absorbing their food from the host plant through specialised roots; leaves opposite, frequently reduced to scales; flowers diœcious or monœcious, regular; in terminal or axillary clusters. [Sidenote: =Razoumofskya americana= (Nutt.) Kuntze. _Dwarf Mistletoe._]