SALICACEAE

WILLOW FAMILY

Shrub, tree, generally dioecious (rarely monoecious)
Stem: trunk < 40 m; wood soft; bark smooth, bitter; buds scaly
Leaves simple, alternate, deciduous; stipules generally deciduous, often large
Inflorescence: catkin, generally appearing before leaves; each flower subtended by disk or 1–2 nectary glands and 1 bract
Flower: perianth 0
Staminate flower: stamens 1–many
Pistillate flower: pistil 1, ovary superior, chamber 1, stigma lobes 2–4
Seeds many; hairs fine, white, cottony
Fruit: capsule; valves 2–4
Genera in family: 2 genera, 340 species: generally temp (except Australia, Malay Archipelago) moist places; many cultivated. Hybridization common; identification often difficult. Family description, key to genera by John O. Sawyer, Jr.

SALIX

WILLOW

George W. Argus

Shrub, tree, dioecious; bud scale 1, not sticky, margins generally fused (or free, overlapping)
Stem: twigs generally flexible and not glaucous
Leaf: blade linear to widely obovate, entire to toothed, generally ± hairy
Inflorescence: dense catkin emerging before, with, or after leaves, sessile or on a short leafy shoot; bract subtending each flower
Flower: perianth 0
Staminate flower: stamens 1–8
Pistillate flower: ovary stalked or sessile, style 1 or 0, stigmas 2, each sometimes 2-lobed; nectaries 1–several, generally rod-like, generally between inflorescence axis and flower
Fruit: valves 2
Species in genus: ± 400 species: ± worldwide, especially n temp, arctic
Etymology: (Latin: ancient name)
Reference: [Argus 1986 Syst Bot Monog 9:1–170; Dorn 1976 Canad J Bot 54:2769–2789]
Difficult, highly variable. Not all specimens will key easily; sprout shoots and other extreme forms are not included in keys, may require field comparison for identification. Studies of variation, hybridization needed.

Native

S. scouleriana Hook.

SCOULER'S WILLOW

Shrub, slender tree, < 10 m
Stem: twigs brownish, hairy or becoming glabrous
Leaves: petiole generally velvety; young leaves hairy; mature blade 29–80 mm, oblanceolate to narrowly elliptic, rounded or acute (base wedge-shaped), entire or irregularly serrate, strongly rolled under, lower surface glaucous, sparsely white-and-rusty-tomentose or densely white-woolly, upper surface shiny, becoming glabrous (except midrib)
Inflorescence appearing before leaves, 15–65 mm, generally sessile; flower bract dark brown or 2-colored
Staminate flower: stamens 2
Pistillate flower: ovary silky, style 0.3–0.6 mm, stalk 0.8–2.3 mm
Chromosomes: 2n=76,114
Ecology: Common. Dry to moist forests, meadows, springs, swamps
Elevation: 90–3400 m.
Bioregional distribution: Northwestern California, High Cascade Range, Sierra Nevada, n Central Coast, San Gabriel Mountains, San Bernardino Mountains, San Jacinto Mountains, Modoc Plateau
Distribution outside California: to Alaska, c Canada, New Mexico, Mexico
Synonyms: var. coetanea C.R. Ball
Horticultural information: IRR or WET, SUN: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24; STBL.