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. breweri Bebb

BREWER'S WILLOW

Shrub < 4 m
Stem: twigs yellow-brown, velvety or silky-tomentose
Leaves: stipules vestigial or leaf-like; young leaves silky; mature blade 58–144 mm, lanceolate to widely elliptic or oblanceolate, acute (base rounded to acute), entire to shallowly wavy-toothed, slightly rolled under, lower surface glaucous, generally densely tomentose, midrib glabrous, upper surface sparsely tomentose
Inflorescence appearing before leaves, 20–85 mm, sessile or on leafy shoots < 5 mm; flower bract tawny to light rose
Staminate flower: stamens 2
Pistillate flower: ovary very densely tomentose, style 0.4–0.8 mm, stalk 0–0.4 mm, nectary generally thread-like
Ecology: Serpentine streamsides
Elevation: 300–1300 m.
Bioregional distribution: North Coast Ranges, San Francisco Bay Area, n&c South Coast Ranges. Hybrids with S. lasiolepis Benth. in Yolo Co. have leaves less hairy, fruit long, slender, stalked, becoming glabrous. Like S. delnortensis C. K. Schneid. but has shorter petioles, flexible twig bases
Horticultural information: IRR or WET, SUN: 4, 5, 6, 7, 8, 9, 14, 15, 16, 17, 22, 23, 24.