Horkelia tenuiloba
Horkelia cuneata
Santa Rosa, Santa Rosa horkelia, Sonoma horkelia, thin-lobed, thin-lobed horkelia
wedge leaf horkelia
ascending to erect, 1–4 dm, hairs ± spreading.
decumbent to erect, (1–)2–6(–7.5) dm, hairs ascending to appressed, sometimes spreading.
weakly planar to ± cylindric, 5–15(–20) × 0.5–1.5 cm;
stipules entire;
leaflets 8–16(–20) per side, ± overlapping especially distally, cuneate to flabellate, 3–10 × 2–10 mm, 1/2 to nearly as wide as long, divided 1/2–3/4+ to midrib into 3–8 linear to narrowly oblanceolate or narrowly elliptic lobes, sparsely villous at least marginally, often with a tuft of hairs apically.
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.
2–5.
1–3(–5).
open to congested, flowers arranged individually and in glomerules, these sometimes subcapitate.
± open to congested, flowers arranged individually and/or in glomerules.
1–6 mm.
1–30(–40) mm.
10 mm diam.;
epicalyx bractlets narrowly to broadly lanceolate, 1–3 × 0.5–1 mm, slightly shorter than sepals, entire;
hypanthium 1–1.2 × 2.5–4.5 mm, less than 1/2 as deep as wide, interior pilose;
sepals spreading to reflexed, lanceolate, 3–5 mm;
petals oblanceolate, 2.5–4.5 × 1.5 mm, apex emarginate;
filaments (1–)1.5–2 × 0.5 mm, anthers 0.4–0.6 mm;
carpels 10–25;
styles 1.8–2.2 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.
light brown, 1.5 mm, smooth or slightly rugose.
brown, 1.5–1.8 mm, smooth or minutely rugose.
= 28.
Horkelia tenuiloba
Horkelia cuneata
Of conservation concern.
Horkelia tenuiloba occurs on the western edges of the northern Coast Ranges in Marin, Mendocino, and Sonoma counties. Populations from San Luis Obispo formerly included in this species now are part of H. yadonii. A specimen (M. K. C[urran], July 5, 1885, UC) unequivocally of H. tenuiloba purportedly from San Luis Obispo is in all likelihood mislabeled with respect to locality.
Horkelia tenuiloba is commonly associated with seral openings in chaparral and woodlands and might be dependent on periodic disturbance by fire.
W. L. Jepson (1909–1943, vol. 2) used Potentilla stenoloba (1895) for the species encompassing the types of Horkelia tenuiloba and P. micheneri. The epithet micheneri (1893) has priority at species rank within Potentilla, since P. tenuiloba (Torrey) Greene is a later homonym of P. tenuiloba Jordan.
(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.)
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 |
CA
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USDA Plants Database
