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. tularensis (J.T. Howell) Munz

KERN PLATEAU HORKELIA

Plant ± matted, grayish
Stem < 25 cm
Leaf 2–10 cm, often ± cylindric; leaflets generally 4–6 per side, ± crowded, generally 3.5–8 mm, divided > 3/4 to base into 5–8 ± oblanceolate lobes, hairs dense
Inflorescence ± dense to open, generally 3–15-flowered; pedicels generally 2–7 mm
Flower: hypanthium width 2.5–4.5 mm, ± 2 X length, inner wall hairy; bractlets generally < 0.5 mm wide, linear; sepals ± 3–4.5 mm; petals ± 3–4 mm, oblong to oblanceolate; filaments 1–2 mm, bases ± 0.5 mm wide, anthers ± 0.8 mm; pistils 5–12, styles ± 2 mm
Fruit ± 2–2.5 mm
Ecology: Dry, rocky balds, flats
Elevation: 2350–2850 m.
Bioregional distribution: s High Sierra Nevada (Bald Mtn area, Tulare Co.)
Horticultural information: In cultivation.