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. sericata S. Watson

HOWELL'S HORKELIA

Plant ± tufted, green to silvery; caudex few-branched; odor indistinct
Stem 15–50 cm; hairs at base ± 1 mm
Leaf 3–15 cm, often ± cylindric; leaflets ± 15 per side, crowded, 2–10 mm, generally divided ± 1/2 to base into < 10 elliptic lobes, hairs many
Inflorescence open; flowers many, ± separate; pedicels generally 1–6 mm
Flower: hypanthium width 2–3 mm, 1–2 X length; bractlets ± 0.5 mm wide, linear-lanceolate; sepals 2.5–4 mm; petals 3–5 mm, narrowly obcordate, often pink-tinged; filaments 0.5–1.5 mm, bases < 0.5 mm wide, anthers ± 0.5 mm; pistils 2–6, styles ± 1.5–2 mm
Fruit 2–2.7 mm
Chromosomes: n=14
Ecology: UNCOMMON. Dry, rocky serpentine clay, open chaparral or pine forest
Elevation: 60–1200 m.
Bioregional distribution: w Klamath Ranges
Distribution outside California: sw Oregon
Synonyms: Potentilla howellii Greene
Variation in hairiness, stipule lobing needs study
Horticultural information: DRN, IRR, SUN: 7, 14, 15, 16, 17, 18, 19, 20, 21.