Horkelia hendersonii

Howell

Fl. N.W. Amer., 180. 1898.

Common names: Henderson’s horkelia
Conservation concernEndemic
Synonyms: Potentilla hendersonii (Howell) J. T. Howell
Treatment appears in FNA Volume 9. Treatment on page 249. Mentioned on page 248.

Plants 1.5–4 dm diam. Stems ascending to erect, 0.8–2 (–2.5) dm. Basal leaves 3–8 × 0.7–1.5 cm; leaflets (5 or) 6–12 per side, overlapping at least distally, cuneate to flabellate, 4–9 (–10) mm, divided 1/2+ to midrib into 3–6 oblanceolate to obovate lobes (often medially notched more than 3/4 to midrib as well), silky villous. Cauline leaves 2–3. Pedicels 2–8 (–10) mm. Flowers (2–) 4–15 (–20), 10 mm diam.; epicalyx bractlets linear, 2.5–4.5 × 0.2–0.5 mm, 2/3 to nearly equal to length of sepals; hypanthium 1–2.5 × (2–) 3–4 (–5) mm, ± 1/2 as deep as wide, interior densely villous; sepals spreading, narrowly lanceolate, 3.5–6 mm, silky hairs silky, 1–1.5 mm; petals often pink-tinged, linear to narrowly oblanceolate, 2.5–5 × 1 mm, apex ± acute to narrowly rounded, sometimes slightly mucronate; filaments pinkish, 2 × 0.5–0.7 mm, glabrous or sparsely pilose adaxially, anthers 0.5–0.7 mm; carpels 8–17; styles (1.5–) 2–3 mm. Achenes dark-brown, 2 mm.


Phenology: Flowering summer.
Habitat: Dry, metamorphosed granite and ultramafic talus slopes, in montane conifer woodlands
Elevation: 2000–2300 m

Discussion

Of conservation concern.

Horkelia hendersonii is one of the more attractive species of the genus, with its grayish mats and dusky pink inflorescences. P. A. Rydberg (1898) placed it initially in his group Capitatae, here restricted to H. fusca, and later (1908c) transferred it to his new group Tenuilobae, which otherwise comprised only H. tenuiloba. The species is known only from Jackson County, Oregon, and an isolated population in adjacent Siskiyou County, California. The populations are vulnerable due to their proximity to popular recreational sites.

Selected References

None.

Lower Taxa

None.

"dm" is not declared as a valid unit of measurement for this property."dm" is not declared as a valid unit of measurement for this property.

... more about "Horkelia hendersonii"
longer than wide +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.07 cm0.7 mm <br />7.0e-4 m <br />) +
Barbara Ertter +  and James L. Reveal +
Howell +
compound +  and simple +
opposite +  and alternate +
3 cm30 mm <br />0.03 m <br /> (8 cm80 mm <br />0.08 m <br />) +
0.7 cm7 mm <br />0.007 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
flattened +
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 +
Henderson’s horkelia +
open to congested +
Calif. +  and Oreg. +
not +  and aggregated +
2000–2300 m +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.45 cm4.5 mm <br />0.0045 m <br />) +
linear +  and lanceolate +
0.02 cm0.2 mm <br />2.0e-4 m <br /> (0.05 cm0.5 mm <br />5.0e-4 m <br />) +
2 cm20 mm <br />0.02 m <br /> (?) +
pilose +  and glabrous +
flattened +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.07 cm0.7 mm <br />7.0e-4 m <br />) +
10 cm100 mm <br />0.1 m <br /> (?) +
4 +  and 15 +
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 />) +
Dry, metamorphosed granite and ultramafic talus slopes, in montane conifer woodlands +
0.1 cm1 mm <br />0.001 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
0.4 cm4 mm <br />0.004 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
0.1 cm1 mm <br />0.001 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
sparsely pilose +  and densely villous +
0.1 cm1 mm <br />0.001 m <br /> (0.55 cm5.5 mm <br />0.0055 m <br />) +
0.3 cm3 mm <br />0.003 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
crassinucellate +
opposite +  and alternate +
marcescent +
winter-persistent +
0.9 cm9 mm <br />0.009 m <br /> (1 cm10 mm <br />0.01 m <br />) +
villous +  and silky +
oblanceolate +  and obovate +
0.4 cm4 mm <br />0.004 m <br /> (0.9 cm9 mm <br />0.009 m <br />) +
oblanceolate +
palmate +  and pinnate +
shallowly toothed +  and deeply divided +
inferior +  and superior +
clustered +, biseriate +  and superposed +
0.8 cm8 mm <br />0.008 m <br /> (1 cm10 mm <br />0.01 m <br />) +
recurved +  and reflexed +
0.2 cm2 mm <br />0.002 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
0 (?) +  and 4 (?) +
free +  and distinct +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
1 cm10 mm <br />0.01 m <br /> (?) +
Flowering summer. +
adnate +, free +, connate +  and distinct +
Fl. N.W. Amer., +
not arillate +
persistent +
free +  and distinct +
lanceolate +
0.35 cm3.5 mm <br />0.0035 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
Conservation concern +  and Endemic +
free +  and distinct +
branched +  and simple +
stramineous +, reddish +  and green +
ascending +  and erect +
1 +  and 10 +
palmate +  and pinnate +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
deciduous +
distinct +
subterminal +
filiform +
rough-thickened +
0.2 cm2 mm <br />0.002 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
Potentilla hendersonii +
Horkelia hendersonii +
Horkelia sect. Hispidulae +
species +
inconspicuous +
enlarged +
reddish +  and grayish green +
hairy +  and inconspicuously conspicuously glandular +