Pacific Willow

Pacific Willow
Salix lasiandra Benth.
A short lived, non colonial, fast growing,
native, pioneer willow is often mistaken for
peach leaf willow or resembling cottonwood
suckers (5, 10, 15). Pacific willow is used for
windbreaks, inexpensive erosion control and
energy plantations in other countries (12, 15,
16). Many willow species, especially pacific
willow, are self-infertile and freely hybridizes
with other willow species. Willow bark has
aspirin like properties used by Native
Americans to cure many common illnesses.
Two varieties occur commonly in the Pacific
Northwest, lasiandra and caudata (9). Also
referred to as Shinning or whiplash willow
and rarely red or yellow willow.
SYN: S. lucida var. lasiandra and S. lucida
ssp. lasiandra.
Plant Characteristics
glaucous, lanceolate shaped, finely toothed, 5-10 cm (2-3.9 in) long,
mature leaves bore on glandular lobed petioles (1, 9).
Inflorescence: Dioecious aments are solitary, thick, hairless, light
reddish, 6-8 mm (0.24-0.31 in) long. Catkin buds are slightly larger
than the duck shaped leaf buds (5). Floral bracts are elliptic to
oblanceolate, often shallowly toothed, pale yellow, deciduous and
hairy (6, 8). Staminate catkins are 18-65 mm (0.70-2.55 in) long (1).
Characteristic of pacific willow are the 4 to 5 stamens and nectaries
(1).
Roots: Rather aggressive moderately deep, widespread fibrous root
system. Roots will bind to Iron and other toxic metals to avoid
poisoning. VAM, vascular arbuscular mycorrhizae, occurs on willow
roots to aid in nutrient uptake. (12)
GENERAL HABITAT CONSIDERATIONS
Soil Types and Conditions: Inhabits a wide variety of deep, sandy,
gravelly, fine textured or acidic to neutral soils typically of alluvial
deposits. Tolerates a thick mollic epipedon occurring as far as 1.6
m (5.2 ft) from active water (4). Pacific willows avoid limestone
deposits (14).
Moisture/temperature requirements: Grows in stream or river
banks, valleys, flood plains, alluvium bottomlands, fast moving
creeks, woodlands, freshwater swamps, willow-alder thickets and
roadside ditches. Occupies moderate elevations from sea level to
0-2,950 m (8,500 ft) in more flood prone areas than other willow
species (7, 13, 15). As the elevation increases up to 1,981 m (6,500
ft), var. caudata becomes shrubbier.
Management Considerations
UTILIZATION
VEGETATIVE CHARACTERISTICS
Form and Stature: This multi-stemmed
shrub or tree normally is 5-15 m (16-49 ft),
but has been observed reaching 20 m (65 ft)
tall (6, 8). The dark gray to dark brown,
vertically ridged, scaly trunk can be up to 60
cm (23 in) thick bearing flexible highly brittle,
glossy stems. Young twigs like young leaves
are covered with fine spreading hairs and with
age become smooth (6, 8). Height and crown
diameter are influenced by site conditions (4).
Leaves: Juvenile leaves are reddish to
yellowish green and coarsely toothed with
long silky hairs maturing into green or
Cultivars
‘Nehalem’ released 1988 Corvallis, Oregon
‘Roland’ 1987 released Alaska PMC
Forage and Palatability: Preferred by cattle when other palatable
forages decrease (16).
Wildlife Use: Deer, elk, moose and rabbits browse willow leaves
and branches (3). Wildlife browsing throughout the year drastically
reduces development. Aments are eaten by small game and song
birds (7). In California, the endangered Least Bell’s vireo frequently
nests in the Pacific willow (15). Heavy beaver use in the winter is
common. Sawflys damage willow branches and leaves by mining,
boring, defoliating and producing galls (12). Pacific willows provide
cover for wildlife and cattle seeking shade.
PLANTING
Growth Season and Seedling Establishment: Blooms mid April
to mid May, flowering as soon as leaves emerge. Establishment by
17.8-25cm (7-10 in) long, one-half-inch thick cuttings by seeds is
possible. Cuttings must be collected, between November and March,
and planted the same day. Roots will appear within 10 days of
planting, so quick placement is important. (10) Prerooted cuttings
will achieve highest establishment. Willows store carbohydrates in
the early stages of active growth, suggesting prerooted cuttings have
more reserves than non-rooted cuttings. Seed establishment should
take place in late spring. The seedbed must be moist until the seeds
germinate and establish. Fertilizing with wood ash or nitrogen
enhances growth. Note that urea based fertilizer inhibits production.
Seeds must be collected and planted promptly because the tiny seeds
have no dormancy, germination will occur within 12-24 hours.
DISTURBANCE
Response to Competition: Naturally, this species is replaced by
cottonwoods or poplars. Overgrazing can cause willows to be replaced
by grasses, especially Kentucky bluegrass. Intolerant of shading,
dense grasses can inhibit seedling establishment. (15)
Response to Grazing: Pacific willow will resprout from the root
crown after light to moderate grazing or browsing (11, 12).
Regeneration may take more than 3 years if grazing is removed or
the riparian corridor is fenced off. Proper grazing can stimulate
enhanced density and growth (4). Late summer grazing won’t
stimulate regrowth.
Response to Fire: Plants with high vigor resprout from root crowns
or stem bases following a light to moderate fire. Extreme fires in
riparian areas are rare but those fires will remove organic matter
damaging or killing the roots. (15)
Response to Drought: Moderately tolerant to periodic droughts.
Once pacific willow is established, roots will be extended searching
for water and eventually form support for the stream banks.
Sources:
1. Argus, George W. 2003. A guide to the identification of
Salix (willows) in Alberta. June-July 2003. Ontario, Canada. 78p.
2. Argus, George W. 2003. A guide to the identification of
willows in Alaska, the Yukon Territory and adjacent regions. Workshop
on willow identification. June-July 2003. Ontario, Canada. 104p.
3. Brunsfeld, Steven and Fredrich Johnson. 1985. Field Guide
To The Willows Of East-Central Idaho. Bulletin 39. Moscow, Idaho:
University of Idaho, Forest, Wildlife, and Range Sciences. 95p.
4. Clary, Warren P. et al. 1996. Response of a depleted
sagebrush steppe riparian system to grazing control and woody
plantings. Intermountain research station: research paper INT-RP492. 32p.
5. Collet, Dominique M. 2004. Willows of Interior Alaska.
US Fish and Wildlife Service. 111p.
6. Cook, Sarah. 1997. A Field Guide to the Common Wetland
Plants of Western Washington and Northwestern Oregon. Seattle:
Seattle Audubon Society. 417p.
7. Darris, Dale and Scott Lambert. 1993. Native willow
varieties for the Pacific Northwest. U.S. Dept. of Agriculture and
Soil conservation. Corvallis, Oregon 15p.
8. Davis, Ray J. 1952. Flora of Idaho. Dubuque, IO: WM.C.
Brown Company. 836p.
9. Hitchcock, C. Leo and Arthur Cronquist. 1973. Flora of
the Pacific Northwest. Seattle, WA: University of Washington Press.
730 p.
10. Klein, Kevin. 2003. Plant Data Sheet: Salix lucida ssp.
lasiandra (pacific willow). Washington State University. 2p.
11. Kindschy, Robert R. 1898. Regrowth of Willow following
simulated Beaver cutting. Wildl. Soc. Bull. 17: 290-294.
12. Kovalchik, Bernard L. 1992. Growth and Yield of willows
in Central Oregon compared to reports in world literature. ProceedingsSymposium on Ecology and mamagement of riparian shrub
communities. Sun Valley, ID. 83-88p.
13. Manning, M.E. and W.G Padgett. 1992. Distribution of
willows on forested of Nevada and Eastern CA. ProceedingsSymposium on Ecology and mamagement of riparian shrub
communities. Sun Valley, ID. 83-88p.
Pacific Willow
Salix lasiandra Benth.
14. Plants for a future. 1997-2000.
Salix exigua. [Accessed: April 12, 2005].
15. Uchytil, Ronald J. 1989. Salix
lasiandra. In: Fire Effects Information
System, [Online]. U.S.D.A, Forest Service,
Rocky Mountain Research Station, Fire
Sciences Laboratory (Producer). Available:
http://www.fs.fed.us/database/feis/ [2005,
April 19].
16. USDA, NRCS. 2004. The
PLANTS Database, Version 3.5
(http://plants.usda.gov). National Plant Data
Center, Baton Rouge, LA 70874-4490 USA.
Prepared by OSU Rangeland Ecology
and Management, April 2005.