Horkelia sect. Capitatae

(Rydberg) O. Stevens

in N. L. Britton et al., N. Amer. Fl. 22(7): 7. 1959.

Basionym: Capitatae Rydberg Monogr. N. Amer. Potentilleae, 122. 1898
Synonyms: Potentilla sect. Capitatae (Rydberg) Crum
Treatment appears in FNA Volume 9. Treatment on page 259. Mentioned on page 248.

Plants forming tufts or open mats, green or reddish, rarely grayish, conspicuously glandular, resinously aromatic. Stems ascending to erect, (0.6–)1–6(–9) dm. Basal leaves planar; stipules entire; leaflets 3–8(–15) per side, separate, sometimes ± overlapping, divided 1/5–3/4+ to midrib into (3–)5–15 teeth or lobes not restricted to apex. Inflorescences open to ± congested, flowers usually arranged in ± capitate glomerules, arranged individually in H. fusca var. filicoides. Pedicels remaining ± straight, outermost sometimes ± reflexed in congested inflorescences, 1–3(–10) mm. Flowers: epicalyx bractlets linear, 0.2–0.3(–0.5) mm wide, entire; hypanthium interior glabrous; sepals acute to acuminate; petals white to pale pink, often veined with pink to rose, ± oblanceolate to cuneate, apex emarginate to truncate or rounded; filaments white, glabrous, anthers longer than wide; carpels 10–25. Achenes 1–1.8 mm, smooth.


w United States.


Species 1.

Rydberg recognized seven species in his group Capitatae, treated here as intergrading variation within a single species. Plants of the section share the characteristic Horkelia odor, glandularity, and planar leaves of sect. Horkelia, but differ in the combination of relatively small, short-pedicelled flowers that (except for var. filicoides) are most commonly aggregated into one or more capitate, purple-suffused glomerules, with linear epicalyx bractlets, oblanceolate-cuneate petals that are often pink-tinged, and relatively short, broad filaments.

Selected References


Lower Taxa