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. prolixa Andersson

MACKENZIE'S WILLOW

Shrub < 5 m
Stem: twigs brownish, glabrous or long-shaggy-hairy
Leaves: stipule tip rounded, young leaves glabrous or hairy; mature blade 50–150 mm, lanceolate to ovate, acuminate (base generally cordate), glabrous, margin gland-dotted to serrate, lower surface glaucous
Inflorescence appearing with leaves, 25–85 mm, sessile or on leafy shoots < 5 mm; flower bract brown, hairs curly
Staminate flower: stamens 2
Pistillate flower: ovary glabrous, style 0.3–1 mm, stalk 1.3–4.2 mm
Ecology: Streams
Elevation: 1600–2000 m.
Bioregional distribution: Klamath Ranges, High Cascade Range, n High Sierra Nevada
Distribution outside California: to n Canada, Utah
Synonyms: S. mackenzieana (Hook.) Andersson; S. cordata Muhlenb. misapplied
Horticultural information: TRY; STBL.