_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.