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FNA | Family List | FNA Vol. 21 | Asteraceae

275. Wyethia Nuttall, J. Acad. Nat. Sci. Philadelphia. 7: 39, plate 5. 1834.

Mules-ears [For Nathaniel Jarvis Wyeth, 1802–1856, early western American explorer]

William A. Weber

Perennials, 15–60(–100) cm (taproots relatively massive; caudices seldom branched). Stems erect (or bending erect from bases), branched mostly from bases. Leaves basal and cauline; alternate; usually petiolate (basal), sometimes sessile; blades (usually pinnately nerved, basal larger than cauline) ± deltate, elliptic-ovate, lanceolate, lance-elliptic, lance-linear, or oblong-ovate, bases truncate to cuneate, margins usually entire, rarely dentate to serrate (sometimes ciliate), faces glabrous or hairy (sometimes gland-dotted or finely stipitate-glandular). Heads radiate, borne singly or 2–5(–8+) in ± corymbiform to racemiform arrays. Involucres hemispheric to campanulate or turbinate, 12–60+ mm diam. Phyllaries persistent, 12–36(–48) in 2–3+ series (subequal to unequal, outer sometimes foliaceous, much larger than inner). Receptacles flat to convex, paleate (paleae conduplicate, at least bases, papery). Ray florets 5–25+, pistillate, fertile; corollas mostly yellow (cream to white in W. helianthoides). Disc florets 35–150+, bisexual, fertile; corollas yellow, tubes much shorter than cylindric throats; lobes 5, ± deltate to lanceolate (style branches stigmatic in 2 barely distinct lines, appendages ± filiform). Cypselae ± prismatic, weakly 3–4-angled (faces glabrous or hairy); pappi 0, or persistent, coroniform (usually lacerate) or of 1–4+ ovate to subulate, erose to lacerate (often basally connate) scales. x = 19.

Species 8 (8 in the flora): w North America.

Some species formerly included in Wyethia are here treated in Agnorhiza and Scabrethia. Balsamorhiza is closely related to Wyethia.


Weber, W. A. 1946. A taxonomic and cytological study of the genus Wyethia, family Compositae, with notes on the related genus Balsamorhiza. Amer. Midl. Naturalist 35: 400–452.

1 Involucres 35–60+ mm diam.; outer phyllaries (30–)40–80+ mm (± foliaceous, much surpassing discs)   (2)
+ Involucres 10–30(–40) mm diam.; outer phyllaries 15–30(–40) mm (not foliaceous, seldom surpassing discs)   (3)
2 (1) Leaf blades: faces glabrous or finely stipitate-glandular, sometimes sparsely pilosulous as well (usually shining); cypselae 10–13 mm   1 Wyethia glabra
+ Leaf blades: faces densely tomentose to tomentulose (usually gland-dotted as well), glabrescent; cypselae 12–15 mm   2 Wyethia helenioides
3 (1) Leaf blades: faces tomentose to tomentulose (at least when young, glabrescent, usuallygland-dotted)   3 Wyethia mollis
+ Leaf blades: faces glabrous, glabrate, hirsute, hirsutulous, hirtellous, pilose, pilosulous, scabrellous, or strigillose (not tomentose to tomentulose, often gland-dotted or stipitate-glandular)   (4)
4 (3) Leaf blades: faces glabrous or glabrate (gland-dotted); phyllary margins not ciliate; cypselae glabrous   (5)
+ Leaf blades: faces usually hirsute, hirsutulous, hirtellous, pilose, pilosulous, scabrellous, or strigillose (sometimes vernicose, rarely finely stipitate-glandular or gland-dotted), sometimes glabrate; phyllary margins ± ciliate; cypselae strigillose or glabrous   (6)
5 (4) Basal leaves: blades lance-elliptic or oblong-lanceolate to lanceolate; rays 8–21(–25), laminae 25–60 mm; cypselae 8–9 mm   4 Wyethia amplexicaulis
+ Basal leaves: blades narrowly oblong-lanceolate to lance-linear; rays 5–8+, lami-nae 18–30 mm; cypselae 6–8 mm   5 Wyethia longicaulis
6 (4) Basal leaves: blades lanceolate to lance-linear; cypselae 7–8 mm, ± strigillose   6 Wyethia angustifolia
+ Basal leaves: blades elliptic-ovate, lanceolate, or lance-elliptic; cypselae 9–11 mm, strigillose or glabrous   (7)
7 (6) Phyllaries 36–48; rays 13–25, laminae (cream to white) 25–45 mm; cypselae strigillose distally and on margins   7 Wyethia helianthoides
+ Phyllaries 16–34; rays 11–12, laminae (yellow) 25–50 mm; cypselaeglabrous   8 Wyethia arizonica

Lower Taxa


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