How to use this key: This key is not made up of opposing choices (it is not dichotomous).  Read through numbered statements until one that is true of the specimen that you are identifying is found, then continue same process in the’ lettered’ sub-sections.  Willows are highly variable; many species are entered in more than one category below.  Take particular note of underlined passages.  For a 2-page key to all native willows of Washington in this format, send a SASE to address above.

You have to know what glaucous means to use this key: covered with a fine, whitish, removable powder.  As you will see in the key, about ½ of our willows have leaves that are glaucous underneath; that is, they have a white powdery substance on the underside that comes off when you rub it.  This can be hard to judge if the leaf is hairy.  You also need to know what glabrous means: hairless, if a leaf is glabrous, it has no hair on it.  Entire refers to leaves with smooth edges, without serrations.

After a little practice you will be able to narrow the tree or shrub in question down to a few species by simply examining the leaves and twigs.  To get to species, you may need the female catkin.  If catkins are not still in season, look for the odd one that may still be stuck on a branch; check also at the base of the plant.  Even if the capsules on the catkins have opened you can tell if they were hairy or glabrous; often the scales (see drawing below) will still be in place as well.  Use the one letter codes (e.g. ‘ch’ means that the seed capsules on the catkin are hairy, while ‘cg’ means the capsules are glabrous, or hairless.  Also look at the little bracts below the capsules and the twigs.

Abbreviations used in the key:  b= floral bract, p= pale, d= dark (dark brown or black), h= hairy, g= glabrous, b d/h= bract dark/hairy, y= yellow, grn= green,  c= capsule, ch= capsule hairy, cg= capsule glabrous, ch/g= capsule hairy or glabrous,  lvs= leaves t= twigs (this year’s growth), th= twigs hairy, tg= twigs glabrous, th/g= hairy or glabrous, lan= lanceolate, ellip= elliptic

Scientific names: Arctic= S. arctica, Barclay= S. barclayi, Bebb= S. bebbiana, Blueberry= S. myrtillifolia, Booth= S. boothii, Cascade= S. cascadensis, Coyote= S. exigua, Drummond= S. drummondiana, Dusky= S. melanopsis, Farr= S. farriae, Geyer= S. geyeriana, Glaucous= S. glauca, Plane-leaved= S. planifolia, Mountain= S. pseudomonticola, Rigid= S. rigida, Scouler= S. scouleriana, Sitka= S. sitchensis, Snow= S. nivalis, Tweedy= S. tweedyii, Undergreen= S. commutata, Whiplash= S. lasiandra,   Synonyms: S. farriae/hastata, lasiandra/lucida, rigida/prolixa.












1.  Dwarf alpine sub-shrubs (lvs all +- entire, all can be glaucous below, all can be hairy or glabrous
Arctic- to 3 dm high, lvs elliptic to obovate, 1-8 x .5-6cm, catkins to 9cm, style .6-2.2mm, bd/h, ch(cg), tg
 Cascade- 1-4 cm high, lvs small, lanceolate to elliptic, 9-26 x 3.8-7.5mm, style .3-1mm, bd/h, ch(cg), th
Snow-  1-4cm high, lvs small, elliptic to obovate, 6-22 x 4-15mm, style .2-.4mm, bp/hairy within, ch, th/g

2.  Leaves very long and narrow, never over 2 cm wide, often grow as colonial shrubs, occasionally become small trees
Coyote- to 25’, lvs very narrow, to 16 x 1cm, glaucous, serrulate or entire, bp/h, ch, th/g; rivers/lakes, low/mid elevation.
Dusky- to 16’, lvs oblong or elliptic, to 8.5 x 2cm,, glaucous, serrulate, bp/h(g), cg, th/g, on rivers, low/mid elevation.
Whiplash- to 30’, lvs lanceol to elliptic, to 15cm, glabrous, margins glandular-serrate, by/h, cg, th/g, rivers/wet areas, low/mid elev.

3.  Leaves hairy at maturity, above and/or below, glaucous below:
A.  Leaves clearly narrowly-lanceolate to narrowly elliptic
 Geyer’s- to 16’, lvs lanceolate to elliptic, to 8 x 1.4 cm, often with brown & white hairs, bp/h, ch, th/g; lakes, low/mid elevations.
Dusky- to 16’, leaves oblong or elliptic, to 8.5 x 2 cm, hairs white, bp/h(g), cg, th/g, along rivers, low/mid elevations.

B.  Leaves wider (not clearly narrowly lanceolate), elliptic, ovate, to obovate and serrate (see next choice for leaves that are entire):
Barclay’s- to 8’, lvs elliptic to obovate, to 9cm, long-hairy, hairy vein above, catkin to 7cm, style .6-2.5mm, bd/h, cg, th/g, mid/alp.
Glaucous- to 12’, lvs oblanceolate to elliptic, to 10cm, pale, long-hairy, style .3-1.4mm, bp/h, ch, th; mesic to wet, mid/alp, rare.
Plane-leaved- <12’, lvs oblanceolate to elliptic, to 6.5cm, short-hairy, petiole grooved above, style .5-2m, bd/h, ch, th/g, mid/alp.
Rigid- to 16’+, lvs ellip, to 10cm, often hair on vein above, floral bract minute, style .3-1mm, bd/g, cg, tg(h), low-mid strms/lakes.

C.  Leaves wider (not clearly narrowly lanceolate), elliptic, ovate, to obovate and entire:
Plane-leaved- <12’, lvs oblan to elliptic, to 6.5cm, glossy above, petiole grooved above, style .5-2mm, bd/h, ch, th/g, mid/alpine.
Scouler’s- lvs obovate, to 8cm, crowded at br tips,  oft with rusty hairs below, style to .5mm, bd/h, ch, th, wet/dry forest, low/mid.
Rigid- to 16’+, lvs ellip, to 10cm, often hair on vein above, floral bract minute, style .3-1mm, bd/g, cg, tg(h), low-mid strms/lakes.

Male flower, anthers

Ripe, seed capsule, split open

Seed capsule at pollination

Female catkin

Male catkin

B. Leaves elliptic to obovate
Booth’s- to 20’, lvs lanceolate to elliptic, to 10x3cm, glossy green above, style .3-1mm, bd/h, cg, th/g, mont/alpine wet areas, rare.
Undergreen- to 10’, lvs to 8cm, elliptic, long hairy, mid vein above hairy, style .5-1.2mm, pb/h, cg(h), th, lake/stream/tundra.
Stika- to 20’, lvs to 12cm, obovate, satiny short-hairy below, 1 stamen per bract (most have two), bd/h, ch, th, wet/dry, low/montane.
Tweedy’s- to 12’, lvs broad-elliptic, to 10x5cm, dull green above, style 1.5-3mm, catkins at branch tips, bd/h, cg, th, subalpine, rare.  

5. Leaves glabrous at maturity or nearly so, and glaucous below
  A. Capsules pubescent:
  Bebb’s- to 30’, lvs obovate, to 8cm, capsule long & thin, style .1-.4mm, bp/h, th, low to mid elevations in wet places.
  Plane-leaved- <12’, lvs oblanceolate or elliptic, to 6.5cm, glossy above, petiole grooved above, style .5-2, bd/h, th/g, mid/alpine.
   Scouler’s- to 40’, lvs obovate, to 8cm, often crowded at br tips, may have rusty hairs below, bd/h, ch, th, wet/dry forest, low/mid.

  B. Capsules glabrous
  Farr’s- to 7’, lvs elliptic to oblanceolate, to 7.5cm, pale yellow-green above, style .3-1.2, bd/h(g), th, subalpine, wet to dry.
  Mountain- to 15’, lvs elliptic to obovate, to 8cm, midrib often hairy, margin glandular-serrate, bd/h, th/g, low/mid elevations.
  Rigid- to 16’+, lvs elliptic, to 10cm, often hairy on vein above, bract minute, style .3-1mm, bd/g, cg, tg(h), low-mid strms/lakes.
  Whiplash-to 30’, lvs narrowly lanceolate to ellip, to 15cm, margins glandular-serrate, by/h, cg, th/g, low/mid, rivers. wet places.

6. Leaves glabrous at maturity or nearly so, not glaucous below:
  A. Leaves serrate:
  Booth’s- to 20’, lvs lanceolate to ellip, to 10x3cm, glossy green above, style .3-1mm, bd/h, cg, th/g, mont/alpine wet areas, rare.
  Tweedy’s- to 12’, lvs broad-ellip, to 10x5cm, dull green above, style long, to 3mm, catkins at branch tips, bd/h, cg, th, subalp, rare.
   Whiplash-to 30’, lvs narrowly lanceolate to ellip, to 15cm, margins glandular-serrate, by/h, cg, th/g, low/mid, rivers. wet places.
  Blueberry-to 3’, lvs elliptic to obovate, to 5cm, branches rooting, bp/h, cg, th/g, bogs & wet areas, mont/alpine, rare, Pasayten.

   B. Leaves entire; Farr’s willow is typically glaucous below (and so-keyed above), but not always
  Booth’s- to 20’, lvs lanceolate to ellip, to 10x3cm, glossy green above, catkins leafless, bd/h, cg, th/g, mont/alpine wet areas, rare.
  Farr’s- to 7’, lvs elliptic to oblanceolate, to 7.5x3cm, shiny or dull  above, catkins on leafy branchlets, bd/h(g), cg, th/g, mont/alp..

Arctic Willow

Barclay Willow

Bebb Willow

Booth Willow

Coyote Willow

Drummond Willow

Dusky Willow

Farr Willow

Glaucous Willow

Rigid Willow

Undergreen Willow

Whiplash Willow

Tweedy’s Willow

Snow Willow

Sitka Willow