Horkelia sericata
Horkelia congesta
Howell's horkelia, silky horkelia
shaggy horkelia, Sierra horkelia
ascending to erect, 1.5–4.5 dm, hairs 1 mm proximally, glands absent or sparse distally.
ascending to erect, 1.5–5 dm, hairs 2–3 mm proximally, glands dense distally.
± cylindric to weakly planar, 3–10 × 0.3–1.2 cm, densely sericeous, often villous on margins apically;
stipules usually entire or forked, rarely pinnately divided into linear lobes;
leaflets (8–)10–20 per side, ± overlapping, elliptic to flabellate, 2–8 × 1–4 mm, 1/2–2/3 as wide as long, divided ± 1/2+ to midrib into (0–)2–4 elliptic lobes 1–2 mm wide, these not restricted to apex.
± planar, (3–)4–15 × 1–3 cm, usually villous at least abaxially, often densely so;
stipules entire, deeply 2-lobed, or pinnately divided into 3–5 linear lobes;
leaflets 2–6 per side, ± separate, narrowly cuneate or lanceolate-elliptic to oblong, 5–20 × (1–)2–5(–6) mm, 1/5–1/2 as wide as long, divided 1/6–1/4 or less to midrib into (0–)3(–5) ± ovate teeth 1–2 mm wide, these restricted to apex.
(2 or)3–5;
stipules 3–8 mm, entire or shallowly 1–2-toothed.
2–7;
stipules 5–25(–30) mm, divided 3/4+ into linear or linear-lanceolate lobes, or incompletely divided or divided no more than 2/3 into lanceolate, often acuminate teeth.
open, flowers arranged individually and/or in non-capitate glomerules.
open to congested, flowers usually arranged in ± capitate glomerules or corymbiform clusters.
1–4 mm.
1–3(–6) mm.
10 mm diam.;
epicalyx bractlets linear-lanceolate, 1.5–3 × 0.5 mm, ± 2/3 length of sepals;
hypanthium 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, 2–4 mm;
petals white to pink or red-veined, narrowly obcordate, 3–4.5(–7) × 2–3 mm, apex ± emarginate;
filaments 0.5–1.5 × 0.2–0.5 mm, anthers 0.4–0.6 mm;
carpels 2–6;
styles 1.5–2 mm.
8–16 mm diam.;
epicalyx bractlets linear to lanceolate or narrowly elliptic, 1–3 × 0.3–0.8 mm, ± 2/3 length of sepals;
hypanthium 2–2.5 × 3–4.5 mm, ± 1/2 to nearly as deep as wide, interior usually glabrous, sometimes sparsely pilose;
sepals spreading, abaxially green, 2–4.5 mm;
petals white to cream, ± obovate, (2.5–)3–6 × (1.5–)2–5 mm, apex ± rounded to ± emarginate;
filaments (0.5–)1–2 × (0.2–)0.4–0.6 mm, anthers 0.4–0.7(–1) mm;
carpels (6–)10–15(–20), styles 1.5–3 mm.
brown, 2–2.5 mm, smooth.
brown, 1.6–2.2 mm, faintly rugose.
= 28.
Horkelia sericata
Horkelia congesta
Of conservation concern.
D. D. Keck (1938) expanded the circumscription of Horkelia sericata to encompass the plants segregated here as H. howellii, on the grounds that intergradation is too extensive to justify taxonomic recognition of the extremes. In this evaluation, however, most collections can be unequivocally divided between plants with compact silvery-sericeous leaves with entire or forked stipules (H. sericata), and plants with larger, greener leaves and pinnately divided stipules (H. howellii). It is not known if the chromosome count provided by P. A. Munz (1959) was derived from H. howellii or H. sericata.
As here circumscribed, Horkelia sericata is a localized taxon known only from Curry County, Oregon, and the Gasquet serpentine area in adjacent Del Norte County, California.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Varieties 2 (2 in the flora).
As discussed by D. D. Keck (1938) and analyzed by T. N. Kaye (unpubl., Oregon Dept. of Agriculture, 1995), Horkelia congesta comprises three population clusters that form a latitudinal gradient in Oregon west of the Cascade Range, transitioning to H. tridentata in the mountains of California. Populations of H. congesta in remnant prairies in the Willamette Valley (probably including the type of H. hirsuta Lindley) have relatively tall, erect stems, pectinate stipules, relatively numerous, narrow leaflets, openly branched inflorescences with flowers in corymbiform clusters, and clawed petals 5–6 × 4–5 mm. In contrast, populations centered in rocky serpentine flats within the Illinois River drainage in Josephine County, which were described by Keck as subsp. nemorosa, tend to have shorter ascending stems, less divided stipules, fewer and broader leaflets, more capitate inflorescences, and scarcely clawed petals 3–4 × 2–3 mm. The differences between these two extremes are blurred by populations from the Umpqua Valley in Douglas County (the probable type locality of H. congesta), as well as scattered populations in northern Jackson and Josephine counties. Based on morphometric analyses of 19 characters, Kaye concluded that the Umpqua material overlapped slightly with plants from the Willamette Valley, while the Josephine County populations clustered separately. He retained the Umpqua and Willamette valley populations as subsp. congesta, with mid stem stipule features of greatest diagnostic value. This taxonomic conclusion is adopted here, with a change of rank from subspecies to variety.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Cauline leaves: stipules divided 3/4+ into linear to linear-lanceolate lobes; inflorescences composed of ± corymbiform clusters to capitate glomerules; petals (3–)4–6 × (2–)3–5 mm; remnant prairies, Willamette and Umpqua valleys, Oregon. | var. congesta |
1. Cauline leaves: stipules incompletely divided or divided no more than 2/3 into lanceolate, often acuminate teeth; inflorescences usually composed of ± capitate glomerules; petals 2.5–3(–4) × (1.5–)2–3 mm; serpentine flats, Illinois River drainage, Oregon, and Del Norte County, California. | var. nemorosa |
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