Flora of Oregon

Herbs perennial; taproots thick, resin-producing.

Stems erect or ascending, leafy, simple or branched.

Leaves basal and cauline, alternate, simple, linear-lanceolate to ovate; basal > cauline.

Inflorescences heads solitary or in corymb- or raceme-like arrays, usually with 1 terminal main head, sometimes with 1–5 axillary heads per stem.

Involucres broadly campanulate to hemispheric.

Receptacles flat to convex; paleate.

Paleae lanceolate, acute, folded around fruits.

Ray florets pistillate; rays yellow or white, 3-lobed, much exceeding involucres.

Disc florets bisexual; corollas yellow, 5-lobed.

Fruits 4-sided, black, glabrous to strigillose; pappi jagged crowns and 1+ longer scales.

2n=38.

Western Mexico and western United States. 14 species; 5 species treated in Flora.

All species of Wyethia are diploid with a chromosome base number of 19 and are capable of hybridizing when they come into contact; however, hybrids are generally rare. Wyethia is most closely related to Balsamorhiza, from which it is distinguished by having cauline leaves. Here, head width measurements are of pressed specimens. The genus was named by Thomas Nuttall after Nathaniel Wyeth, who led the expedition on which the type species of the genus, W. helianthoides, was collected.

Flora of North America

as described under Wyethia

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