Horkelia tridentata var. tridentata

Synonyms: Potentilla tilingii (Regel) Greene
Treatment appears in FNA Volume 9. Treatment on page 269. Mentioned on page 268.

Stems decumbent to nearly erect, 1–4 (–7) dm. Inflorescences composed of 1+ 5–40-flowered ± capitate glomerules, these sometimes expanding with age. Flowers 4–9 mm diam.; hypanthium 2–3.5 (–5) mm diam., interior glabrous; petals linear to oblanceolate, (1.5–) 2–3.5 (–4.5) × 0.3–1 mm, usually ± equal to or longer than sepals, apex acute to obtuse; filaments 0.5–1 (–2) × 0.1–0.2 mm, anthers 0.2–0.3 (–0.4) mm; styles 1–2 mm. Achenes 1.5–2 mm, lightly rugose. 2n = 28.


Phenology: Flowering spring–summer.
Habitat: Open areas, primarily in sagebrush communities and conifer woodlands, mainly on granitic or volcanic soil
Elevation: 300–2500 m

Discussion

Variety tridentata occurs throughout the Cascade Mountains and Sierra Nevada of California, and barely extends into southern Oregon near Ashland, Josephine County, where the presence of distal cauline glands on some plants indicates possible introgression with Horkelia congesta. A specimen from Glendale, Oregon, (Jones s.n., POM) that was annotated and cited by D. D. Keck (1938) as H. congesta subsp. nemorosa is fully comparable to the Ashland material of var. tridentata; the apparent disjunction in Douglas County needs to be confirmed.

Selected References

None.

Lower Taxa

None.

"/2lengthofsepals" is not declared as a valid unit of measurement for this property.No values specified."dm" is not declared as a valid unit of measurement for this property.

light-brown +
1.5mm +  and 2mm +
0.03 cm0.3 mm <br />3.0e-4 m <br /> (0.04 cm0.4 mm <br />4.0e-4 m <br />) +
shorter than wide +  and longer +
0.02 cm0.2 mm <br />2.0e-4 m <br /> (0.03 cm0.3 mm <br />3.0e-4 m <br />) +
truncate +  and emarginate +
Barbara Ertter +  and James L. Reveal +
Torrey in War Department [U.S.] +
compound +  and simple +
opposite +  and alternate +
3 cm30 mm <br />0.03 m <br /> (4 cm40 mm <br />0.04 m <br />) +
3 cm30 mm <br />0.03 m <br /> (12 cm120 mm <br />0.12 m <br />) +
1 cm10 mm <br />0.01 m <br /> (3 cm30 mm <br />0.03 m <br />) +
flattened +
Tridentatae +
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 +
Calif. +  and Oreg. +
not +  and aggregated +
300–2500 m +
0.2 cm2 mm <br />0.002 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
linear +  and lanceolate or narrowly elliptic +
0.02 cm0.2 mm <br />2.0e-4 m <br /> (0.04 cm0.4 mm <br />4.0e-4 m <br />) +
0.1 cm1 mm <br />0.001 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (0.08 cm0.8 mm <br />8.0e-4 m <br />) +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
flattened +
0.01 cm0.1 mm <br />1.0e-4 m <br /> (0.02 cm0.2 mm <br />2.0e-4 m <br />) +
open to congested +
0.4 cm4 mm <br />0.004 m <br /> (0.9 cm9 mm <br />0.009 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 />) +
1+5-40-flowered +
expanding +
Open areas, primarily in sagebrush communities and conifer woodlands, mainly on granitic or volcanic soil +
0.1 cm1 mm <br />0.001 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
0.2 cm2 mm <br />0.002 m <br /> (0.35 cm3.5 mm <br />0.0035 m <br />) +
0.1 cm1 mm <br />0.001 m <br /> (0.25 cm2.5 mm <br />0.0025 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 +
separate +  and slightly overlapping +
2 cm20 mm <br />0.02 m <br /> (3 cm30 mm <br />0.03 m <br />) +
0.7 cm7 mm <br />0.007 m <br /> (1 cm10 mm <br />0.01 m <br />) +
0.5 cm5 mm <br />0.005 m <br /> (2 cm20 mm <br />0.02 m <br />) +
divided +, elliptic +  and cuneate-oblong +
0.15 cm1.5 mm <br />0.0015 m <br /> (?) +  and 0.7 cm7 mm <br />0.007 m <br /> (?) +
linear +  and filiform +
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 cm10 mm <br />0.01 m <br />) +
0.2 cm2 mm <br />0.002 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
0.35 cm3.5 mm <br />0.0035 m <br /> (0.45 cm4.5 mm <br />0.0045 m <br />) +
0 (?) +  and 4 (?) +
free +  and distinct +
0.2 cm2 mm <br />0.002 m <br /> (0.35 cm3.5 mm <br />0.0035 m <br />) +
usually more or less equal to or longer +
0.03 cm0.3 mm <br />3.0e-4 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
Flowering spring–summer. +
adnate +, free +, connate +  and distinct +
in War Department [U.S.], Pacif. Railr. Rep. +
not arillate +
abaxially green +  and reddish +
persistent +
free +  and distinct +
obtuse +  and acute +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
free +  and distinct +
branched +  and simple +
stramineous +, reddish +  and green +
decumbent +  and nearly erect +
1 +  and 10 +
palmate +  and pinnate +
0.3 cm3 mm <br />0.003 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
deciduous +
distinct +
subterminal +
filiform +
rough-thickened +
0.1 cm1 mm <br />0.001 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
Potentilla tilingii +
Horkelia tridentata var. tridentata +
Horkelia tridentata +
variety +
triangular +
1 cm10 mm <br />0.01 m <br /> (?) +
inconspicuous +
enlarged +
plant +  and rosette-forming +
hairy +  and inconspicuously conspicuously glandular +