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. lutea Nutt.

YELLOW WILLOW

Shrub, small tree, < 7 m
Stem: twigs yellow-gray or yellow-brown; glabrous or hairy
Leaves: young leaves glabrous or silky; mature blade 42–116 mm, lanceolate to oblanceolate, acuminate (base acute to rounded), entire, gland-dotted to finely crenate, glabrous to sparsely hairy, dull above, glaucous below
Inflorescence appearing just before or with leaves, 15–75 mm, sessile or on leafy shoots < 8 mm; flower bract brown, glabrous or sparsely curly-hairy
Staminate flower: stamens 2
Pistillate flower: ovary glabrous, style 0.2–0.6 mm, stalk 1–3.4 mm
Chromosomes: 2n=38
Ecology: Creek margins, wet meadows
Elevation: 900–3100 m.
Bioregional distribution: c&s High Sierra Nevada (especially eastern slope), San Bernardino Mountains, San Jacinto Mountains, Great Basin Floristic Province, w Mojave Desert
Distribution outside California: to w&c Canada, NE
Flowering time: May–Jun
Synonyms: var. watsonii (Bebb) Jeps
Horticultural information: WET, SUN: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24; STBL.