ROSACEAE

ROSE FAMILY

Annual to tree
Leaves simple to pinnately to palmately compound, generally alternate; stipules free to fused, persistent to deciduous
Inflorescence: cyme, raceme, panicle, or flowers solitary
Flower generally bisexual, radial; hypanthium free or fused to ovary, saucer- to funnel-shaped, often with bractlets alternate with sepals; sepals generally 5; petals generally 5, free; stamens (0)5–many, pistils (0)1–many, simple or compound; ovary superior to inferior, styles 1–5
Fruit: achene, follicle, drupe, pome, or blackberry- to raspberry-like
Seeds generally 1–5
Genera in family: 110 genera, ± 3000 species: worldwide, especially temp. Many cultivated for ornamental and fruit, especially Cotoneaster , Fragaria , Malus , Prunus , Pyracantha, Rosa , and Rubus
Reference: [Robertson 1974 J Arnold Arbor 55:303–332,344–401,611–662]
Family description, key to genera by Barbara Ertter and Dieter H. Wilken.

PRUNUS

Dieter H. Wilken

Shrub or tree
Stem: bark gray to red-brown
Leaves generally alternate, simple, generally glabrous; stipules deciduous
Inflorescence: raceme or umbel-like cluster, often on short branchlets
Flower: hypanthium cup- to urn-shaped; sepals spreading to reflexed; stamens 15+, generally in 2+ whorls; pistil 1, ovary superior, chamber 1, ovules 2, style 1, stigma subspheric
Fruit: drupe, generally ovoid to spheric
Species in genus: ± 400 species: temp North America, Eurasia, n Africa; many cultivated for wood, ornamental, edible fruit; some persisting near human habitation (P. armeniaca , apricot; P. avium , sweet cherry; P. cerasus , sour cherry; P. domestica , plum; P. laurocerasus , laurel cherry; P. lusitanica , portugal laurel; P. mahaleb ; P. persica , peach). Seeds of many species ± TOXIC from production of hydrocyanic acid.

Native

P. virginiana L. var. demissa (Nutt.) Torr.

WESTERN CHOKE-CHERRY

Shrub or small tree < 6 m
Leaves deciduous; petiole 10–25 mm; blade 50–100 mm, elliptic to obovate, finely serrate, base rounded to ± cordate, tip generally acute
Inflorescence: raceme; flowers many; pedicel 5–8 mm
Flower: petals 4–7 mm, white
Fruit 6–14 mm, ovoid to spheric, glabrous, dark red to black; pulp ± fleshy
Chromosomes: 2n=16
Ecology: Rocky slopes, canyons, scrub, oak/pine woodland, coniferous forest
Elevation: 100–2900 m.
Bioregional distribution: California Floristic Province (except coast, Great Central Valley), Great Basin Floristic Province
Distribution outside California: to British Columbia, c US, Texas, n Mexico
Flowering time: May–Jun
Synonyms: var. melanocarpa (Nelson) Sarg
Var. virginiana of e North America, generally a tall tree, sometimes cultivated
Horticultural information: DRN, SUN or part SHD: 4, 5, 6, 14, 15, 16, 17 &IRR: 1, 2, 3, 7, 8, 9, 10, 18, 19, 20, 21, 22, 23, 24; STBL; rather INV.