Salix scouleriana

Scouler's willow

Seed from Salix scouleriana

Plant Info

Kingdom:	Plantae
Division:	Magnoliophyta
Class:	Magnoliopsida
Order:	Malpighiales
Family:	Salicaceae
Genus:	Salix
Species:	S. scouleriana

Binomial name

Salix scouleriana
Barratt ex Hook.

Salix scouleriana commonly known as Scouler's Willow is a tree in the Salicaceae family. Synonyms: Salix brachystachys Benth. Salix capreoides Anderss. Salix flavescens Nutt. Salix nuttallii Sarg. Salix stagnalis Nutt.

General Description

Scouler’s willow, also known as fire willow, Nuttall willow, mountain willow, and black willow, is a deciduous shrub or small tree, depending on the environment. It usually has multiple stems that reach 2 to 7 m in height in dry, cold, high elevation, and other difficult environments, and 10 to 20 m in favorable sites. The stems are straight and support few branches generally resulting in narrow crowns. The root system is fibrous, deep, and widespread. The thick sapwood is nearly white, and heartwood is light brown tinged with red. Stem bark is thin, gray or dark brown with broad, flat ridges. Twigs are stout and whitish green. Leaves are oblanceolate to elliptic, 5 to 12.5 cm long, mostly short-pointed at the apex and tapered toward the base with entire to sparsely wavy-toothed margins. The leaves are dark-green and nearly hairless above and white- or grayish-hairy below. Scouler’s willow is dioecious, having male and female flowers on different trees. Tiny flowers are grouped in “pussy willow”-like catkins. The anthers, two per flower, are yellow, sometimes tipped with red; pistols are red. Fruits are light reddish-brown, long-pointed capsules about 0.75 cm long. At maturity, they open to release a white fluff with imbedded tiny seeds. The species has 2n = 76 or 114 chromosomes (Anonymous 2003, Department of Ecology 2003, Harrington 1964, Peattie 1953, Sargent 1923, Viereck and Little 1972).

Range

Scouler’s willow occurs from south central Alaska to central Manitoba, in the Black Hills of South Dakota, in the Rocky Mountains south to New Mexico and Arizona, and along the coast through British Colombia, Washington, Oregon, and California (Natural Resources Conservation Service 2003, Peattie 1953, Treeguide.com 2003).

Ecology

Scouler’s willow is the most common upland willow through most of its range. It invades quickly and abundantly after fires and logging (Viereck and Little 1972). Mineral soil seedbeds are required for seedling establishment (Forest Practices Branch 1997). In northern areas, Scouler’s willow occurs in muskegs, willow thickets, disturbed areas, and forests (Welsh 1974). At lower latitudes, the species grows in former clearcuts, burned areas, thinned forests, and areas of natural disturbance such as avalanche areas and river flood zones. These are all moist, well-drained to poorly drained sites. Although this willow tolerates drier conditions than most other willows, it does not tolerate xeric conditions. Scouler’s willow is a component in a large number of vegetation types throughout its range (Anderson 2001). With few exceptions, it is the only willow found growing with other trees in upland Western forests (Johnson 1995). Soils of all textures, including skeletal soils and soils derived from most parent materials are colonized. Sites may vary from near sea level to about 3,000 m in elevation (Peattie 1953). Scouler’s willow is top-killed by all but gentle fires, but usually greater than 65 percent of the plants sprout quickly afterwards (Anderson 2001). The species is intolerant of shade, and when overtopped by conifers and other hardwoods, it begins to decline.

Reproduction

Scouler’s willow flowers from April through June, flowers appearing before leaves, often while snow is still on the ground, and fruiting occurs from May through July, depending on area. The flowers are insect pollinated. There are about 14,300 cleaned seeds/g. Germination, which is epigeal, begins to occur in 12 to 24 hours after seeds alight on wet ground. Germination usually reaches 95 percent in 1 or 2 days (Brinkman 1974). The seeds are dispersed by the wind. Plants sprout from the root collar when cut or top-killed. Pieces of stem and root will root and grow if partially buried in moist soil (Forest Practices Branch 1997).

Growth and Management

Annual height growth of sprouts from cut stems varies from 1 to 3 m/year. Up to 60 sprouts are produced per stem (Forest Practices Branch 1997). Maximum height at 20 years is about 9 m. At higher elevations, shrubs reach 4 to 5 m in 15 years after which growth slows until a maximum height of 10 m is reached (Natural Resources Conservation Service 2003). Fruits should be collected by hand or with pruning poles as soon as they turn from green to yellow. The capsules are air-dried until opening. Generally, the seeds should be sown as soon as possible because they remain viable for only a few days. Seed can be stored in sealed containers under refrigeration for 4 to 6 weeks, but germination begins to drop rapidly after 10 days. Seeds are broadcast on well-prepared beds that are kept continually moist until germination and seedling emergence. Light is required for successful germination (Brinkman 1974). Recommended spacing using rooted cuttings for erosion control is 1.8 m by 1.8 m; for unrooted whips or shorter cuttings, 0.6 m. Rooted cuttings can be grown to 3 m tall in containers. Cuttings should be 45 to 60 cm long, and whips (not recommended) should be 1.2 m long (Department of Ecology 2003).

Benefits

Scouler’s willow protects the soil and helps return sites to forest cover following disturbance. When growing along streams, it helps protect the stream banks from erosion and shade the watercourse, thus maintaining cooler water temperatures. It is an important browse species for domestic livestock and wild animals. Cattle, sheep, and goats all like it as browse. It is sometimes the most preferred food species for white tailed, black tailed and mule deer, elk, moose, and bighorn sheep. Small mammals, bears, upland game birds, and waterfowl feed to a lesser extent on leaves, buds, and seeds. Fresh browse (twigs and leaves) contain 41 percent dry matter, 4 percent protein, 2 percent fat, 20.8 percent nitrogen-free extract, 11.2 percent crude fiber, and good quantities of mineral nutrients (Anderson 2001). The cover provided by Scouler’s willow is important for mammals and birds. The flowers provide pollen and nectar to honey bees in early spring (Anderson 2001). The wood, which is soft and close-grained, is not sawn into lumber but is used to a limited extent for firewood and wood carving (Viereck and Little 1972). The Secwepemc people of British Colombia used Scouler’s willow wood for smoking fish, drying meat, and constructing fishing weirs, the inner bark for lashing, sowing, cordage, and headbands, and decoctions of twigs for treating pimples, body odor, and diaper rash (Secwepemc Cultural and Education Society 2003).

References

Anderson, M.D. 2001. Salix scouleriana. In: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, Missoula, MT. http://www.fs.fed.us/database/feis/plants/tree/salsco/all.html 57 p.
Anonymous. 2003. Treatment from the Jepson manual: Salicaceae. University of California, Berkeley, CA. http://ucjeps.berkeley.edu/chibin/get_JM_treatment.pl?7043,7050,7079
Brinkman, K.A. 1974. Salix L., willow. In: C.S. Schopmeyer, tech. coord. Seeds of woody plants in the United States. Agriculture Handbook 450. </p
U.S. Department of Agriculture, Forest Service, Washington, DC. p. 746-750.
Department of Ecology. 2003. Plant selection guide. State of Washington, Department of Ecology, Olympia, WA. http://www.ecy.wa.gov/programs/sea/pubs/93-30/table3.html 6 p.
Forest Practices Branch. 1997. Operational summary for vegetation management: willow complex. ISBN 0-7726-3166-2. Forest Practices Branch, Ministry of Forests, Victoria, British Colombia, Canada. 11 p.
Harrington, H.D. 1964. Manual of the plants of Colorado. Sage Books, Denver, CO. 666 p.
Johnson, F.D. 1995. Wild trees of Idaho. University of Idaho Press, Moscow, ID. 212 p.
Natural Resources Conservation Service. 2003. Plants profile: Salix scouleriana Barratt ex Hook. http://plants.usda.gov/chi_bin/plant_search.cgi?mode=Scientific+Name&keywordquery=Salix+scouleriana&earl=plant_search 4 p.
Peattie, D.C. 1953. A natural history of western trees. Houghton Mifflin Company, Boston, MA. 751 p.
Sargent, C.S. 1923. Manual of the trees of North America (exclusive of Mexico). Houghton Mifflin, Boston, MA. 910 p.
Secwepemc Cultural and Education Society. 2003. Flood plain garden. Secwepemc Nation, Kamloops, BC, Canada. http://www.secwepemc.org/SECethnogardens2/flood_plain_garden.htm 4 p.
Treeguide.com. 2003. Scouler willow, Salix scouleriana Barratt ex Hook. http://www.treeguide.com/Species.asp?Region=NorthAmerican&SpeciesID=996 2 p.
Viereck, L.A. and E.L. Little, Jr. 1972. Alaska trees and shrubs. Agriculture Handbook 410. Forest Service, U.S. Department of Agriculture, Washington, DC. 265 p.
Welsh, S.L. 1974. Anderson’s flora of Alaska and adjacent parts of Canada. Brigham Young University Press, Provo, UT. 724 p.
John K. Francis, Research Forester, U.S. Department of Agriculture, Forest Service, International Institute of Tropical Forestry, Jardín Botánico, 1201 Calle Ceiba, San Juan, PR 009261119. in cooperation with the University of Puerto Rico, Río Piedras, PR 00936-4984