Salix glauca

Salix glaucais a species of flowering plant in thewillow familyknown by the common namesgray willow,grayleaf willow,white willow,andglaucous willow.It is native to North America, where it occurs throughout much ofAlaska,northern and western Canada, and the contiguous United States south through theRocky Mountainsto northernNew Mexico.It can also be found inGreenland,northwestern Europe, and Siberia.

Salix glauca
Conservation status
Least Concern(IUCN 3.1)
Secure(NatureServe)
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Rosids
Order:	Malpighiales
Family:	Salicaceae
Genus:	Salix
Species:	S. glauca
Binomial name
Salix glauca L.
Synonyms
Salix pseudolapponum

Dominating the Greenland tundra

Description

Thiswillowis usually ashrubgrowing up to 1.2 m (3.9 ft) tall, but in appropriate habitat it becomes a tree up to 6 m (20 ft) tall. The smooth gray bark becomes furrowed with age. The species isdioecious,with male and female reproductive parts occurring on separate individuals.This species has secondarysexual dimorphism,with male and female individuals different in function or morphology in aspects other than their reproductive structures. For example, female plants are more sensitive todroughtconditions.The seed stays on the plant until fall, when it isdispersed.The seed is coated in downy fibers that help it disperse on the wind and on water. Unlike the seeds of many other willows, these do notgerminateimmediately on contact with the substrate, but overwinter under the snow and sprout in the spring. This provides coldstratificationto the seeds, and allows them a few weeks more to develop than in summer-dispersing willows.

Distribution and habitat

In the northern part of its range, this plant codominates with other species of willow onfloodplainsand in shrubby riparian andtundrahabitat. It may also grow scattered throughout coniferous forests and woodlands, dominated often byspruces.In the southern part of its range, it grows inalpineandsubalpine climates.Like many other willows, it colonizes freshly cleared habitat, such as floodplains recently scoured by water and forests recently burned.

Taxonomy

The taxonomy ofS. glaucahas been described as "confusing".With considerable geographic variation across its wide circumboreal-polar range,S. glaucamay be considered "a very widespread and polymorphic species or species group", with currently no consensus whether it should be subdivided into races, subspecies or varieties. Formally and informally, there are a number of recognized subspecies (such asglauca,stipulifera,acutifolia,callicarpaea)and varieties (such asacutifolia,glauca,stipulata,villosa),but there are only small morphological differences to tell them apart.Furthermore,S. glaucais known to form hybrids with other willows, resulting in intermediates that are visually difficult to distinguish from one another.Some varieties and subspecies have very specific or limited distribution, though. The hybridS. arctophila × S. glaucasubsp.callicarpaea,for instance, is not found in Canada, and is common in eastern parts ofGreenland,but absent from the west, whereasS. glaucasubsp.glaucais not found on Greenland at all.

Ecology

As with other willows,S. glaucais an important food source for a variety of animals, particularly winteringungulates,providing them with a rich source of calcium and phosphorus. It is considered moderately important as moosebrowse,and during the winter it constitutes much of the diet forsnowshoe hares.

Use

Native Americansused parts of willows, including this species, for medicinal purposes, basket weaving, to make bows and arrows, and for building animal traps.

External links

• The Nature Conservancy
• Flora of North America