Wavy-leaved or Sitka Alder Birch Betulaceae Alnus sinuata (Regel) Rydb.
These are sweet-scented shrubs mostly 2-4 meters tall. Young bark is reddish brown, glandular dotted, but glabrous. The older bark is grayish-black. The alternately arranged, ovate leaves vary from 3 to 10 cm long. The base is rounded or cordate, but the apex is acute to slightly acuminate. The margins vary from serrate-denticulate to strongly sinuate. The upper surface is glabrous, but the lower surface varies from hairy overall to hairy on only the veins. Both male and female catkins originate on the current year's growth. The pistillate catkins are 3-6 per branch. The staminate catkins may grow as long as 10 cm. The fruits have thin, broad, membranous wings which are usually more than twice as wide as the nutlet.

Alnus sinuata (Regel) Rydb. Sitka Alder, Wavy-leaved Alder Betulaceae Birch Family

CHARACTERISTICS
shrubs commonly 4-5 , sometimes up to 8 meters tall
bark reddish brown, then becoming gray-black
young growth covered by non-stipitate glands
Unisexual flowers always in unisexual catkins which develop with the leaves on growth of current year
new twigs generally glabrous
pollen flowers always in pendant catkins
the main bracts subtend 2 smaller bracts which subtend 3-6 flowers
each flower contains 3-4 stamens surrounded by a 4-parted perianth
pistillate flowers are in cone-like catkins because the scales are hardened and persistent
each hardened scale subtends 2 naked flowers which are subtended by 2 or 3 small bracts


LEAVES
ovate, 3-10 cm long, acute to sub-cordate at base, acute apex; margins finely once or twice serrulate, usually sinuate; only slightly paler beneath, hairy on veins or over entire surface, upper surface usually glabrous.

FLOWERS
develop on current years growth. Staminate catkins up to 10 cm long
the pistillate flowers 3-6 on the same branch in catkins up to 1.5 cm long and less than 1 cm in diameter, each catkin borne on a stalk 2-3 times as long as the catkin.

FRUIT
with a thin membranous wing at least ½ as broad as the nutlet


HABITAT
moist woods, streambanks, margins of ponds, open montane slopes up to timberline

DISTRIBUTION
Alaska south to the Cascades and Washington Olympic Mountains, through western Oregon to mountains of northern California, north central and eastern Washington, Montana and Idaho in the Rocky mountains of Colorado.
OTHER
too small to of much economic use except for firewood. Dried leaves and bark were sometimes used to make a decoction for a simple tea and for external washes. It is astringent, mildly heating and could also be used to “tone” the small intestinal lining for better food absorption and to aid in fat metabolism.
Even small alders are being utilized in Canada. They are making shavings of the trunks of both alder and quaking aspen. These are glued together into sheets called Oriented Strand Board (OSB) which are used for sub-flooring, sub-roofing, sheeting on houses and for making I beams that are used for rafters, non-squeaking floor joists and many other uses. The American lumbering industry has not yet begun manufacturing OSB.

Images:
1, 2, 3, 4
Photos and content written by Karl Holte, 2002