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mesa horkelia, wedgeleaf horkelia

wedge leaf horkelia

Habit Plants green; eglandular hairs sparse or absent, spreading, glandular hairs not obscured. Plants matted or tufted, green to grayish.
Stems

erect, 3–6 dm.

decumbent to erect, (1–)2–6(–7.5) dm, hairs ascending to appressed, sometimes spreading.

Basal leaves

planar, (5–)10–30 × 1.5–4(–5) cm;

stipules entire or basally lobed;

leaflets 5–12 per side, separate to slightly overlapping, ± elliptic to obovate or oblanceolate, 5–25(–30) × 5–15(–25) mm, ± 1/2 to nearly as wide as long, divided less than 1/3 to midrib into (5–)10–15 oblanceolate to obovate teeth, sparsely pilose to glabrate or sericeous.

Cauline leaves

1–3(–5).

Leaflets

5–12 per side, elliptic to obovate, 5–25 mm, distinctly pinnately veined.

Inflorescences

open, most flowers arranged individually.

± open to congested, flowers arranged individually and/or in glomerules.

Pedicels

(2–)5–10 mm, proximalmost to 40 mm.

1–30(–40) mm.

Flowers

hypanthium interior rim usually glabrous, sometimes sparsely pilose;

petals oblanceolate to narrowly obovate, 2–4 mm wide;

filaments 1–2.5 × 0.5–2 mm.

12–17 mm diam.;

epicalyx bractlets lanceolate to ovate, 3–5 × 1.5–3 mm, 2/3–3/4 length of sepals, entire;

hypanthium 1.5–2 × 4–7 mm, less than 1/2 as deep as wide, interior glabrous or pilose in a narrow ring;

sepals ± reflexed to spreading, lanceolate, 4–6.5 mm;

petals oblanceolate to narrowly obovate, 4–8 × 1.5–4 mm, apex obtuse to rounded;

filaments 1–3 × 0.5–2 mm, anthers 0.7–1.1 mm;

carpels (30–)40–60(–80);

styles 2–3 mm.

Achenes

brown, 1.5–1.8 mm, smooth or minutely rugose.

Horkelia cuneata var. puberula

Horkelia cuneata

Phenology Flowering spring–summer.
Habitat Coastal ranges away from the immediate coast, sandy to gravelly soil, coastal sage and chaparral communities
Elevation 70–900 m (200–3000 ft)
Distribution
from FNA
CA
[BONAP county map]
from FNA
CA
[WildflowerSearch map]
[BONAP county map]
Discussion

Of conservation concern.

At its most distinctive, var. puberula is represented by historic collections from the hills and plains of Los Angeles, western Riverside, extreme southwestern San Bernardino, and northwestern San Diego counties; these populations have now largely been destroyed by urbanization. Scattered populations still exist within this core area, to what extent and with what level of ensured continuity remains uncertain. In addition, multiple populations of Horkelia cuneata from as far north and west as San Luis Obispo County have characteristics of var. puberula; these tend to intergrade with var. cuneata, as do some historic collections from the core area.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Varieties 3 (3 in the flora).

As noted by D. D. Keck (1938) and B. Ertter (1997b), recognition of subunits within Horkelia cuneata is complicated by the abundance of intermediates, to the extent that a complete transition exists between the decumbent, densely hairy coastal extreme with a congested inflorescence, represented by var. sericea, and the erect, green-glandular interior extreme with an open inflorescence, represented by var. puberula. The traditional division into three infraspecific units is maintained here to emphasize the distinctiveness of the extremes, which would qualify as specifically distinct were they not ends of a continuum. The extremes are furthermore threatened by ongoing decimation of suitable habitats at the northern (San Francisco Bay Area) and southern (greater Los Angeles) ends of the species range.

Determining the correct name of Horkelia cuneata if treated as a species of Potentilla is complicated. Potentilla cuneata (Lindley) Baillon ex Munz & I. M. Johnston (1925) and P. puberula Greene are both later homonyms, while P. multijuga Lehmann has been conserved with a conserved type to maintain established usage for an unrelated species of Potentilla (B. Ertter and J. L. Reveal 2008). J. T. Howell (1945) adopted P. lindleyi; however, as noted by R. F. Hoover (1966), P. kelloggii has priority at species rank by a matter of months. The latter is accordingly the correct name in Potentilla for H. cuneata.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Plants: eglandular hairs sparse or absent, glandular hairs evident; hypanthium interior rim usually glabrous, sometimes sparsely pilose; pedicels (2–)5–10 mm, proximalmost to 40 mm; stems erect.
var. puberula
1. Plants: eglandular hairs moderately abundant to dense, glandular hairs evident or obscured; hypanthium interior rim ± or densely pilose; pedicels 1–5 mm, proximalmost to 15 mm; stems decumbent to erect
→ 2
2. Plants ± green, eglandular hairs moderately abundant, spreading to ascending, glandular hairs usually evident; stems ascending to erect.
var. cuneata
2. Plants grayish-sericeous, eglandular hairs dense, ascending to appressed, glandular hairs obscured; stems decumbent to ascending.
var. sericea
Source FNA vol. 9, p. 255. FNA vol. 9, p. 254.
Parent taxa Rosaceae > subfam. Rosoideae > tribe Potentilleae > Horkelia > sect. Horkelia > Horkelia cuneata Rosaceae > subfam. Rosoideae > tribe Potentilleae > Horkelia > sect. Horkelia
Sibling taxa
H. cuneata var. cuneata, H. cuneata var. sericea
H. bolanderi, H. californica, H. clevelandii, H. congesta, H. daucifolia, H. fusca, H. hendersonii, H. hispidula, H. howellii, H. marinensis, H. parryi, H. rydbergii, H. sericata, H. tenuiloba, H. tridentata, H. truncata, H. tularensis, H. wilderae, H. yadonii
Subordinate taxa
H. cuneata var. cuneata, H. cuneata var. puberula, H. cuneata var. sericea
Synonyms H. puberula, H. cuneata subsp. puberula, P. kelloggii var. puberula, P. lindleyi var. puberula Potentilla kelloggii var. cuneata, P. lindleyi
Name authority (Rydberg) Ertter & Reveal: Novon 17: 318. (2007) Lindley: Edwards’s Bot. Reg. 23: sub plate 1997. (1837)
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