Horkelia howellii

(Greene) Rydberg

Bull. Torrey Bot. Club 25: 55. 1898.

Common names: Howell’s or Klamath horkelia
Conservation concernEndemicIllustrated
Basionym: Potentilla howellii Greene Pittonia 1: 104. 1887
Treatment appears in FNA Volume 9. Treatment on page 265. Mentioned on page 266.

Plants tufted to openly matted, ± green. Stems ascending to erect, (0.9–) 1.5–5 dm, hairs 1 mm proximally, glands absent or sparse distally. Basal leaves ± cylindric to weakly planar, 5–15 × 0.5–1.8 (–2.5) cm, usually villous to pilose at least marginally, often glabrescent; stipules deeply 2-lobed or pinnately divided into 3–5 linear to filiform lobes that often form a tangled mass; leaflets 10–15 per side, ± overlapping, elliptic to flabellate, (3–) 4–10 (–15) × 2–8 mm, 1/2 to as wide as long, divided 1/2–3/4 to midrib into (0–) 2–4 elliptic to linear lobes 1–2 mm wide, these not restricted to apex. Cauline leaves (2 or) 3–5; stipules 5–12 (–15) mm, entire to deeply 2–4-lobed or toothed (usually on 1 side). Inflorescences open, flowers arranged individually and/or in noncapitate glomerules. Pedicels 1–6 (–12) mm. Flowers 10 mm diam.; epicalyx bractlets linear-lanceolate, 1–3 × 0.5 mm, ± 2/3 length of sepals; hypanthium 1.1–1.5 × 2–3 mm, ± 1/2 to as deep as wide, interior glabrous; sepals spreading to reflexed, abaxially green to reddish or purplish, 2.5–4.5 mm; petals white to pink or red-veined, narrowly obcordate, 3–5 × 2–3 mm, apex truncate or emarginate; filaments 0.5–1.7 × 0.2–0.5 mm, anthers 0.4–0.6 mm; carpels 2–6; styles 1.5–2 mm. Achenes brown, 2–2.7 mm, smooth.


Phenology: Flowering summer.
Habitat: Chaparral, oak-conifer woodlands, mainly on serpentine soil
Elevation: 60–1200 m

Discussion

Of conservation concern.

As noted above, Horkelia howellii comprises the bulk of what D. D. Keck (1938) and subsequent floras included in H. sericata, and the range of the latter is fully encompassed within that of the former. As here circumscribed, H. howellii occurs in northwestern California and southwestern Oregon. The handful of collections from Humboldt and Trinity counties, California, including the type of Potentilla laxiflora Drew, have leaves approaching H. daucifolia but the inflorescence of H. howellii; exact petal color is uncertain.

Selected References

None.

Lower Taxa

None.

No values specified.No values specified."dm" is not declared as a valid unit of measurement for this property.

... more about "Horkelia howellii"
rugose +  and smooth +
2mm +  and 2.7mm +
shorter than wide +  and longer +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (0.06 cm0.6 mm <br />6.0e-4 m <br />) +
emarginate +  and truncate +
Barbara Ertter +  and James L. Reveal +
(Greene) Rydberg +
compound +  and simple +
opposite +  and alternate +
1.8 cm18 mm <br />0.018 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
5 cm50 mm <br />0.05 m <br /> (15 cm150 mm <br />0.15 m <br />) +
0.5 cm5 mm <br />0.005 m <br /> (1.8 cm18 mm <br />0.018 m <br />) +
flattened +
Potentilla howellii +
30 cm300 mm <br />0.3 m <br /> (40 cm400 mm <br />0.4 m <br />) +
planar +  and cylindric +
2 cm20 mm <br />0.02 m <br /> (30 cm300 mm <br />0.3 m <br />) +
reduced +
free +  and distinct +
Howell’s or Klamath horkelia +
open to congested +
Calif. +  and Oreg. +
not +  and aggregated +
60–1200 m +
linear-lanceolate +
0.5 cm5 mm <br />0.005 m <br /> (?) +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.17 cm1.7 mm <br />0.0017 m <br />) +
flattened +
0.02 cm0.2 mm <br />2.0e-4 m <br /> (0.05 cm0.5 mm <br />5.0e-4 m <br />) +
10 cm100 mm <br />0.1 m <br /> (?) +
unisexual +  and bisexual +
not +  and aggregated +
obliquely ovoid +  and reniform +
0.08 cm0.8 mm <br />8.0e-4 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
Chaparral, oak-conifer woodlands, mainly on serpentine soil +
1 cm10 mm <br />0.01 m <br /> (?) +
0.11 cm1.1 mm <br />0.0011 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
0.1 cm1 mm <br />0.001 m <br /> (0.55 cm5.5 mm <br />0.0055 m <br />) +
crassinucellate +
opposite +  and alternate +
marcescent +
winter-persistent +
1 cm10 mm <br />0.01 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
0.4 cm4 mm <br />0.004 m <br /> (1 cm10 mm <br />0.01 m <br />) +
divided +, elliptic +  and flabellate +
0.2 cm2 mm <br />0.002 m <br /> (?) +  and 0.8 cm8 mm <br />0.008 m <br /> (?) +
linear +  and filiform +
1mm +  and 2mm +
palmate +  and pinnate +
shallowly toothed +  and deeply divided +
aromatic +
inferior +  and superior +
clustered +, biseriate +  and superposed +
0.6 cm6 mm <br />0.006 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
0.1 cm1 mm <br />0.001 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
0 (?) +  and 4 (?) +
White (?) +  and Pink (?) +
free +  and distinct +
0.3 cm3 mm <br />0.003 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
0.2 cm2 mm <br />0.002 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
Flowering summer. +
adnate +, free +, connate +  and distinct +
Bull. Torrey Bot. Club +
not arillate +
abaxially green +  and reddish or purplish +
persistent +
free +  and distinct +
spreading +  and reflexed +
obtuse +  and acute +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.45 cm4.5 mm <br />0.0045 m <br />) +
Conservation concern +, Endemic +  and Illustrated +
free +  and distinct +
branched +  and simple +
stramineous +, reddish +  and green +
ascending +  and erect +
1 +  and 10 +
palmate +  and pinnate +
1.2 cm12 mm <br />0.012 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
0.5 cm5 mm <br />0.005 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
deciduous +
distinct +
subterminal +
filiform +
rough-thickened +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
Ambiguae +, Hirsutae +, Horkelia sect. Hirsutae +, Sericatae +  and Horkelia sect. Sericatae +
Horkelia howellii +
Horkelia sect. Tridentatae +
species +
inconspicuous +
enlarged +
plant +  and matted +
hairy +  and inconspicuously conspicuously glandular +