Horkelia sect. Hispidulae

Ertter & Reveal

Novon 17: 316. 2007.

Conservation concernEndemic
Treatment appears in FNA Volume 9. Treatment on page 248. Mentioned on page 247, 250.

Plants forming dense mats, usually grayish green, sometimes reddish, inconspicuously glandular, not resinously aromatic. Stems decumbent to erect, 0.3–2.5 dm. Basal leaves ± cylindric to weakly planar; stipules entire; leaflets 4–14 per side, overlapping at least distally, divided 1/2–3/4+ to midrib into 3–8 lobes not restricted to apex. Inflorescences ± congested, flowers arranged in dense corymbiform clusters. Pedicels remaining straight, 2–8 (–12) mm. Flowers: epicalyx bractlets linear to lanceolate, 0.3–0.5 (–0.8) mm wide, entire; hypanthium interior sparsely pilose to densely villous; sepals acute; petals white, sometimes pink-tinged, narrowly oblanceolate to narrowly elliptic or oblong, apex usually acute to rounded to truncate, sometimes slightly mucronate or emarginate; filaments white to pinkish, glabrous or sparsely pilose adaxially, anthers longer than wide; carpels 5–18 (–20). Achenes 1.5–2.5 mm, smooth.

Distribution

w United States

Discussion

Species 3 (3 in the flora).

Section Hispidulae accommodates three widely separated, localized species, with plants all forming tight, densely hairy mats in rocky sites at elevations of 2000 to 3400 m in the White Mountains, southern Sierra Nevada, and Siskiyou Mountains of California, adjacent Nevada, and southwestern Oregon.

When describing Horkelia tularensis (as Potentilla tularensis), Howell compared it to H. hispidula with the speculation that these interior species bordering the Great Basin were relicts of an evolutionary line distinct from the more coastal species. Given the geographic proximity to Horkeliella, which serves as a morphologic bridge between Horkelia and Ivesia, it is possible that sect. Hispidulae represents the relictual ancestral radiation within the genus.

Selected References

None.

Key

1 Sepals narrowly lanceolate, with silky hairs 1–1.5 mm; hypanthium interior densely villous; petals often pink-tinged; Siskiyou Mountains, California and Oregon. Horkelia hendersonii
1 Sepals broadly lanceolate, with stiff hairs 0.5–1 mm; hypanthium interior sparsely pilose; petals not pink-tinged; Sierra Nevada and White Mountains, California and Nevada > 2
2 Basal leaves: leaflets 4–6(–10) per side; cauline leaves 1 or 2; carpels 5–12; s Sierra Nevada. Horkelia tularensis
2 Basal leaves: leaflets (6–)10–14 per side; cauline leaves 3–7; carpels (10–)12–18(–20); White Mountains. Horkelia hispidula

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

... more about "Horkelia sect. Hispidulae"
1.5mm +  and 2.5mm +
longer than wide +
Barbara Ertter +  and James L. Reveal +
Ertter & Reveal +
compound +  and simple +
opposite +  and alternate +
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 +
open to congested +
w United States +
not +  and aggregated +
linear +  and lanceolate +
0.03 cm0.3 mm <br />3.0e-4 m <br /> (0.05 cm0.5 mm <br />5.0e-4 m <br />) +
white +  and pinkish +
pilose +  and glabrous +
flattened +
0.4 cm4 mm <br />0.004 m <br /> (1.7 cm17 mm <br />0.017 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 />) +
sparsely pilose +  and densely villous +
0 +  and 1/2 +
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 +
oblanceolate +
palmate +  and pinnate +
shallowly toothed +  and deeply divided +
inferior +  and superior +
clustered +, biseriate +  and superposed +
recurved +  and reflexed +
0 (?) +  and 4 (?) +
free +  and distinct +
adnate +, free +, connate +  and distinct +
not arillate +
persistent +
free +  and distinct +
erect +, spreading +  and strongly reflexed +
Conservation concern +  and Endemic +
free +  and distinct +
branched +  and simple +
stramineous +, reddish +  and green +
decumbent +  and erect +
1 +  and 10 +
palmate +  and pinnate +
deciduous +
distinct +
subterminal +
filiform +
rough-thickened +
Potentilla sect. Horkelia +  and Potentilla subg. Horkelia +
Horkelia sect. Hispidulae +
Horkelia +
section +
inconspicuous +
enlarged +
reddish +  and grayish green +
hairy +  and inconspicuously conspicuously glandular +