TREATMENT FROM THE JEPSON MANUAL	previous taxon | next taxon Jepson Interchange (more information)
	©Copyright 1993 by the Regents of the University of California Print edition is available from the University of California Press

	The second edition of The Jepson Manual (2012) is available from the University of California Press
	See also the Jepson eFlora, which parallels the Second Edition

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.

HORKELIA

Barbara Ertter

Perennial, generally ± glandular, generally resinous-smelling; caudex generally branched
Stem generally ascending to erect
Leaves generally basal, odd-1-pinnate, generally ± flat; cauline alternate, reduced upward; uppermost lateral leaflets generally ± fused with terminal
Inflorescence: cyme, open or of dense clusters; pedicels generally straight
Flower: hypanthium a ± flat-bottomed cup, width ± 2 X length; bractlets 5, generally 2/3 sepals; sepals 5, often reflexed; petals 5, generally ± = sepals, blunt, white; stamens 10, filaments flat, often forming a tube; pistils 2–many, ovaries superior, styles jointed below fruit tip, ± thicker at base
Fruit: achene
Species in genus: 19 species: w North America
Etymology: (J. Horkel, German plant physiologist, 1769–1846)
Data apply to basal leaves, pressed hypanthia.

Native

H. tridentata Torr.

Plant rosetted or tufted, ± gray, ± odorless; caudex 0–few-branched
Stem decumbent to erect, < 45 cm, generally ± glabrous
Leaf 3–12 cm; leaflets 2–5 per side, separated, 5–30 mm, generally elliptic to oblong, ± 3-toothed < 1/4 to base (rarely entire), at least lower surface ± densely hairy
Inflorescence: clusters 1–many, ± head-like, generally 3–40-flowered; pedicels generally 1–6 mm
Flower: hypanthium width 2–5 mm, 1–2 X length; bractlets < 0.5 mm wide, linear; sepals generally 1.5–3 mm; petals 1.5–4 mm, linear to widely oblanceolate; filaments 1–2 mm, bases generally ± 0.2–0.5 mm wide, anthers 0.2–0.5 mm; pistils 5–15, styles 1–2.5 mm
Fruit 1.5–2.5 mm
Ecology: Dry, open coniferous forest
Elevation: 300–2500 m.
Bioregional distribution: Klamath Ranges, North Coast Ranges, Cascade Range, Sierra Nevada, Modoc Plateau
Distribution outside California: s Oregon
Sspp. intergrade extensively
Horticultural information: DRN, IRR, SUN: 1, 2, 3, 7, 14, 15, 16, 17, 18; DFCLT.

Native

subsp. tridentata

Stem decumbent to ± erect
Inflorescence: clusters 1–many
Flower 4–7 mm wide; hypanthium width generally 2–3.5, inner wall generally glabrous; petals generally = or > sepals, generally narrowly lanceolate; filaments generally 0.5–1 mm
Fruit 1.5–2 mm
Chromosomes: n=14
Ecology: Granitic or volcanic soils
Elevation: 300–2500 m.
Bioregional distribution: Cascade Range, Sierra Nevada, Modoc Plateau
Distribution outside California: s Oregon