Mountain Alder is a common name for two different alders; Alnus
viridis subsp. crispa, also called Green Alder and Alnus incana
subsp. tenuifolia, also called Grey Alder or Thinleaf Alder.
The Mountain Alder, our common one locally, is a large shrub or
small tree 3-12 m tall with smooth grey bark even in old age. The
leaves are shiny green, ovoid, 3-8 cm long and 2-6 cm broad. The
flowers are catkins, appearing late in spring after the leaves
emerge (unlike other alders which flower before leafing out); the
male catkins are pendulous, 4-8 cm long, the female catkins 1 cm
long and 0.7 cm broad when mature in late autumn, in clusters of
3-10 on a branched stem.
The seeds are small, 1-2 mm long, light brown with a narrow
encircling wing.
It is a light-demanding, fast-growing shrub that grows well on
poorer soils. In many areas, it is a highly characteristic colonist
of avalanche chutes in mountains, where potentially competing
larger trees are killed by regular avalanche damage.
The Mountain Alder survives the avalanches through its ability
to re-grow from the roots and broken stumps. Unlike some other
alders, it does not require moist soil, and is a colonist of screes
and shallow stony slopes. It also commonly grows on subarctic river
gravels, particularly in northern Siberia, Alaska and Canada,
occupying areas similarly disrupted by ice floes during spring
river ice breakup; in this habitat it commonly occurs mixed with
shrubby willows.
It is sometimes used for afforestation on infertile soils which
it enriches by means of its nitrogen-fixing nodules, while not
growing large enough to compete with the intended timber crop.
Goose hunting in Schefferville this alder used to give my partner,
Gary Peckham, nightmares as getting to a few good spots required a
bushwack through several hundred meters of them