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. hookeriana Hook.

COASTAL WILLOW

Shrub, small tree, < 8 m
Stem: twigs brownish, generally thinly glaucous, densely tomentose or soft-shaggy-hairy, becoming glabrous, brittle at base
Leaves: young leaves white- or white-and-rusty-hairy; mature blade 46–113 mm, elliptic to widely ovate, entire to coarsely crenate, rounded to acuminate (base acute), rarely glabrous, lower surface glaucous, shaggy-hairy, upper surface highly glossy, tomentose (rarely glabrous)
Inflorescence appearing before leaves, 30–140 mm, sessile or on leafy shoots < 10 mm; flower bract dark brown
Staminate flower: stamens 2
Pistillate flower: ovary glabrous or tomentose, style 0.6–1.4 mm, stalk 1–2 mm
Chromosomes: 2n=57
Ecology: Coastal dunes, floodplains, meadows
Elevation: < 100 m.
Bioregional distribution: North Coast (<100 m), n Outer North Coast Ranges (500–1000 m)
Distribution outside California: to Alaska
Synonyms: S. piperi Bebb
Glabrous and densely tomentose forms intergrade, may occur in same population. Higher elevation glabrous form (Humboldt Co.) warrants study. May hybridize with S. lasiolepis Benth
Horticultural information: IRR or WET: 4, 5, 6, 7, 14, 15, 16, 17, 19, 20, 21, 22, 23, 24; STBL.