Field & Lab. 19: 71. 1951.
Perennials, (5–) 16–40 (–70) cm; taprooted. Stems 1–50+, decumbent to erect (sometimes brown or reddish-brown, sometimes whitish distally, sometimes ± brittle), sparsely to densely hispido-strigose, sparsely to abundantly long-hispid, eglandular or sparsely to densely stipitate-glandular. Leaves generally not crowded; proximal cauline petiolate, blades oblanceolate, (90–) 220–400 (–600) × (2–) 4–8 (–13) mm, bases cuneate, margins flat, usually entire, rarely with 1–2 apical teeth, strigoso-ciliate, sparsely to abundantly long-hispido-strigose proximally, apices acute to obtuse, sometimes mucronate, faces sparsely to densely hispido-strigose, eglandular or sparsely to densely stipitate-glandular; distal sessile, blades usually lanceolate or oblanceolate to oblong, rarely ovate or lanceolate-triangular, (4–) 15–28 (–42) × (1.5–) 3.5–7 (–12.5) mm, bases attenuate to convex-cuneate to rounded, margins usually flat, rarely remotely undulate, strigoso-ciliate, sparsely to abundantly long-hispido-strigose proximally, apices acute to obtuse, sometimes mucronate, faces sparsely to densely hispido-strigose, eglandular or sparsely to densely stipitate-glandular. Heads 1–16 (–42), in usually open, corymbiform, rarely paniculiform arrays. Peduncles (4–) 15–41 (–98) mm, sparsely to densely hispido-canescent, eglandular or sparsely to densely stipitate-glandular; bracts 1–7+, usually linear-oblanceolate, rarely leaflike and linear-oblanceolate, usually greatly reduced, margins usually flat, rarely remotely undulate, strigoso-ciliate, sparsely to abundantly long-hispido-strigose proximally, apices acute, sometimes mucronate, faces sparsely to densely hispido-strigose, eglandular or sparsely to densely stipitate-glandular; rarely 1–2 leaflike, oblanceolate bracts subtending heads. Involucres narrowly cylindric to campanulate, (5–) 6–9.5 (–13) mm. Phyllaries in 4–5 series, lanceolate to linear-lanceolate or triangular-lancelate, unequal (outer 1/5–1/3 length of inner), margins scarious, sometimes reddish purple distally, ciliate distally or apically, faces sparsely to densely strigose, eglandular or sparsely to moderately stipitate-glandular. Ray-florets (5–) 10–20 (–38); laminae (3.5–) 6.5–11 (–20) × 1–2 (–3) mm. Disc-florets (10–) 20–50 (–85); corollas barely ampliate, (4–) 5–6 (–8) mm, glabrous or glabrate (few, minute hairs), lobes 0.4–0.75 (–1) mm, glabrous or glabrate (hairs 0.1–0.35 mm). Cypselae monomorphic, obconic, compressed, 1.7–2.7 (–3.4) mm, ribs 4–8 (–10) (rarely brownish), faces sparsely to moderately strigose; pappi off-white, outer of linear scales 0.25–1 mm, inner of 30–45 bristle (4–) 5–6.5 (–8.5) mm, longest weakly clavate (usually equaling or longer than corollas). 2n = 18, 36.
Alta., B.C., Man., Ont., Sask., Ariz., Calif., Colo., Idaho, Ill., Iowa, Kans., Mich., Minn., Mont., N.Dak., N.Mex., Nebr., Nev., Oreg., S.Dak., Tex., Utah, Wash., Wis., Wyo.
Varieties 9 (9 in the flora).
Heterotheca villosa is variable in stem height, leaf base shape, stem and leaf indument, number of heads, and number of florets. Thus, the species is difficult to circumscribe because each variety has a suite of diagnostic traits and a distribution that is restricted to a portion of the range of the species. Generally, var. minor (glandular), and to a lesser extent, var. foliosa (eglandular) are the glue holding the other varieties together in a widely distributed polymorphic species; this is comparable to the situation in H. sessiliflora, in which var. echioides is the glue. Variety minor hybridizes with all other varieties. Numerous local races occur that are sometimes quite distinct when extreme, but they intergrade with one or more other races, especially in var. minor (J. C. Semple 1996). The species is divided here on the basis of indument features, leaf shape, and stem height, paralleling the infraspecific treatments of H. fulcrata and H. sessiliflora. H. A. Gleason and A. Cronquist (1991) and Cronquist (1994) acknowledged the variability of the species and the existence of many local races, but lumped most of these into var. villosa and var. hispida of Chrysopsis villosa, in which they also included H. camporum, H. canescens, H. fulcrata, H. pumila, H. stenophylla var. angustifolia, H. viscida, and H. zionensis. Diploid races are usually distinct from each other, but each has given rise to one or more tetraploid lines that are less distinct. The treatment here is based on the detailed presentation in Semple.
|1||Stems sparsely to densely hispido-strigose, sparsely to densely stipitate-glandular; distal cauline leaves sparsely to densely hispido-strigose (hairs 2–100/mm²), sparsely to densely stipitate-glandular (glands 2–60/mm²)||> 2|
|1||Stems moderately to densely hispido-strigose, eglandular or sparsely stipitate-glandular; distal leaf faces moderately to densely strigose (hairs 25–200/mm²), eglandular or sparsely stipitate-glandular (rarely more densely so)||> 5|
|2||Distal cauline leaf blades ovate to oblanceolate or lanceolate to triangular-lanceolate, rarely oblong, glands sometimes more numerous than hairs/mm²; arrays corymbiform||> 3|
|2||Distal cauline leaf blades linear, lanceolate, narrowly to broadly oblong, or narrowly ovate, glands less numerous than hairs/mm²; arrays congested, corymbiform to subumbelliform; w Great Plains, foothills of Front Range, White Mountains (New Mexico)||> 4|
|3||Distal cauline leaf blades usually narrowly to broadly oblanceolate, sometimes oblong, sometimes ovate in mountains, margins flat to remotely undulate, apices obtuse to acute, indument sparse to moderate; arrays compact, branches usually not very long; phyllaries usually moderately strigose (hairs to 1 mm), often stipitate-glandular||Heterotheca villosa var. minor|
|3||Distal cauline leaf blades narrowly lanceolate to triangular-lanceolate, apices sharply acute, margins flat; arrays lax, branches often very long; phyllaries sparsely short-strigose, hairs usually less than 0.3 mm, sparsely to moderately stipitate-glandular; rock outcrops, margins of arroyos, rocky banks, Arizona, Idaho, Nevada, Utah, disjunct in Little San Bernardino Mountains, California||Heterotheca villosa var. scabra|
|4||Distal leaf blades often perpendicular to stems, linear to broadly oblong, sometimes small (less than 10 mm), faces moderately hispido-strigose (hairs 9–56/mm²), moderately to densely stipitate-glandular (glands 9–36/mm²), glands sometimes more than hairs; ray laminae (3.5–)6.9–11(–12) mm; lower elevations in mountains and foothills, Colorado and New Mexico, Great Plains, Colorado, w Nebraska, New Mexico, se Wyoming||Heterotheca villosa var. nana|
|4||Distal leaf blades (perpendicular proximally, ascending distally) lanceolate to ovate-oblong, faces moderately to densely strigose (hairs usually 42–93/mm²), sparsely to moderately stipitate-glandular (glands usually 4–37/mm²); ray laminae (8.5–)9–12(–14) mm; mid elevations of Sierra Blanca, New Mexico, and mountains to s, w||Heterotheca villosa var. sierrablancensis|
|5||Stems often abundantly long-hirsute; distal cauline leaf blades narrowly to broadly oblong; bracts subtending heads often surpassing them||> 6|
|5||Stems sparsely to moderately long-hirsute; distal cauline leaf blades narrowly to broadly oblanceolate; bracts subtending heads small or none||> 7|
|6||Leaf faces moderately strigose (hairs usually not obscuring faces); involucres broadly campanulate; rays showy, (12–)17–30 (averaging 21), laminae (8.5–)9.9–14.5 mm (averaging 11.5 mm); ne Great Plains||Heterotheca villosa var. ballardii|
|6||Leaf faces moderately to densely hispido-strigose (hairs sometimes obscuring faces); involucres narrowly campanulate; rays less showy, (7–)13–22 (averaging 17), laminae 8–11.4(–12.4) mm (averaging 10 mm); mountains and w prairies||Heterotheca villosa var. foliosa|
|7||Stems moderately to densely strigose, sparsely to abundantly long-hirsute; distal cauline leaf faces moderately strigose (20–60 hairs/mm²); Great Plains, scattered in hills and mountains||Heterotheca villosa var. villosa|
|7||Stems sparsely long-hirsute; distal cauline leaf faces densely strigose (60–270 hairs/mm²)||> 8|
|8||Stems 5–22 cm, sparsely long-hirsute; distal leaf faces densely strigose (84–140 hairs/mm²), sparsely to moderately stipitate-glandular; geyser basins, Yellowstone National Park, gravelly stream banks, e Teton National Park, rare further s in Wyoming||Heterotheca villosa var. depressa|
|8||Stems (12–)30–50(–75) cm, usually sparsely, rarely abundantly long-hirsute; distal leaf faces densely strigose (60–270 hairs/mm²), eglandular or sparsely stipitate-glandular; grasslands, wooded hillsides, mountains, Arizona, Colorado, New Mexico, Utah||Heterotheca villosa var. pedunculata|
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