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wedge leaf horkelia

wedge leaf horkelia

Habit Plants ± green; eglandular hairs moderately abundant, spreading to ascending, glandular hairs usually evident. Plants matted or tufted, green to grayish.
Stems

ascending to erect, (1–)2–5 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 or oblanceolate, 5–15 mm, distinctly pinnately veined.

Inflorescences

± open;

most flowers arranged in glomerules.

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

Pedicels

1–5 mm, proximalmost to 15 mm.

1–30(–40) mm.

Flowers

hypanthium interior rim ± pilose;

petals oblanceolate, 2.5–3.5 mm wide;

filaments 1.5–3 × 0.5–1 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.

2n

= 28.

Horkelia cuneata var. cuneata

Horkelia cuneata

Phenology Flowering spring–summer.
Habitat Coastal sand dunes and hills, coastal scrub communities
Elevation 0–400 m (0–1300 ft)
Distribution
from FNA
CA
[BONAP county map]
from FNA
CA
[WildflowerSearch map]
[BONAP county map]
Discussion

Most extant populations of Horkelia cuneata are referable to var. cuneata or intermediates between it and the other two varieties, with the greatest concentrations around Monterey Bay and from Morro Bay to Santa Barbara. At its most distinctive, var. cuneata occurs from Santa Cruz to Los Angeles counties, often sharing habitat with var. sericea though also occurring somewhat more inland, but not as far inland as var. puberula. Although not as endangered as the extremes, unequivocal var. cuneata is far from abundant and shares some of the same threats to its prime coastal habitat.

(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. puberula, 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 Potentilla lindleyi var. lepida Potentilla kelloggii var. cuneata, P. lindleyi
Name authority unknown Lindley: Edwards’s Bot. Reg. 23: sub plate 1997. (1837)
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