JUGLANDACEAE

WALNUT FAMILY

Dieter H. Wilken

Shrub, tree, generally monoecious
Leaves generally odd-1-pinnate, alternate, deciduous; stipules 0
Inflorescence: catkin, generally appearing before leaves, generally clustered; flowers generally solitary in bract axils
Staminate inflorescence generally pendent, generally elongate, generally many-flowered, on last year's twigs
Pistillate inflorescence generally erect; flowers 1–3, at tip of new twigs
Staminate flower: sepals 3–6; petals 0; stamens 3–many; pistil 0 or vestigial
Pistillate flower: sepals 3–6; petals 0; stamens 0; pistil 1, ovary inferior, chamber 1 above, generally 2 below, styles generally 2, plumose
Fruit: nut enclosed in a ± fleshy husk, drupe-like
Genera in family: 7 genera, ± 60 species: n temp, subtropical mtns; some ornamental, cultivated for wood, nuts (Carya hickory, pecan; Juglans )
Reference: [Elias 1972 J Arnold Arb 53:26–51]

JUGLANS

WALNUT

Shrub, tree, generally monoecious
Stem generally erect; bark smooth to furrowed in age, gray to brown; twig centers chambered
Staminate flower: calyx lobes generally 4, ± fused to bract
Pistillate flower: calyx lobes 4, generally ± fused to bract and bractlets, with them forming husk in fruit
Fruit in clusters, generally spheric; husk leathery, strong-smelling, indehiscent yet ± deciduous
Species in genus: 21 species: temp North America., n temp Eur, Asia, South America
Etymology: (Latin: walnut)
Reference: [Howell 1973 Madroño 22:144]
Wood used for interior finishing, furniture; source of nuts.

Native

J. californica S. Watson

CALIFORNIA BLACK WALNUT

Shrub, tree
Stem: trunks 1–5, generally < 25 m; bark gray to brown; twigs brown
Leaf: leaflets 11–19, 3–10 cm, lanceolate to ovate, toothed
Fruit (including husk) 2–3.5 cm diam; woody nut shell ± grooved
Ecology: Slopes, canyons, valleys
Elevation: 50–900 m.
Bioregional distribution: s Inner North Coast Ranges, s Sacramento Valley, n San Joaquin Valley, San Francisco Bay Area, Outer South Coast Ranges, South Coast, s Transverse Ranges, n Peninsular Ranges.Sometimes cultivated; hybrids with J. regia few, synthetic.

Native

var. hindsii Jeps.

NORTHERN CALIFORNIA BLACK WALNUT

Stem: trunk 1, generally 15–25 m
Leaf: leaflets 5–10 cm
Fruit (including husk) generally 3–3.5 cm diam
Ecology: Canyons, valleys
Elevation: 50–200 m.
Bioregional distribution: s Inner North Coast Ranges, s Sacramento Valley, n San Joaquin Valley, San Francisco Bay Area
Synonyms: J. hindsii (Jeps.) R.E. Sm
Reported as occurring at pre-Spanish native American campsites. Formerly cultivated as rootstock for J. regia with which it hybridizes readily
Horticultural information: 4, 5, 6, 7, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, IRR: 8, 9, 10, 11.