Fl. Bor.-Amer. 1: 306, plate 107. 1833.
Perennials, 5–50(–90) cm, sericeous, tomentose, or glabrous, sometimes sessile- or stipitate-glandular (taproots woody, caudices often short, branched). Stems decumbent to ascending or erect (leafy or subscapiform, often red-tinged), mostly simple. Leaves basal and cauline; alternate; basal usually short-petiolate, cauline sessile; basal blades 1-nerved, oblanceolate to elliptic or nearly linear (3–250(–450) × 3–30 mm, bases usually attenuate), margins entire or spinulose-dentate or -serrate or shallowly laciniate; cauline often lanceolate, reduced distally (bases sometimes clasping). Heads usually radiate or disciform, rarely discoid, borne singly or 2–5(–15) in racemiform, spiciform, or loose, corymbiform arrays (subtended by leafy bracts in P. carthamoides and P. radiata). Involucres hemispheric to narrowly campanulate, 5–15(–30) × 5–60 mm. Phyllaries 10–40 in 2–6 series, appressed to loosely spreading, 1-nerved, oblanceolate to oblong or linear, equal or unequal, usually herbaceous and yellow-green or with distinct, green apical patch, sometimes proximal 2/3 white-indurate (apices occasionally squarrose, obtuse or acute, occasionally mucronate), faces glabrous or densely villous to tomentose. Receptacles convex, pitted, epaleate. Ray florets 10–80, pistillate, fertile; corollas yellow (usually 10–35 mm, sometimes reduced, not surpassing involucres). Disc florets 20–100, bisexual, fertile; corollas yellow, tubes ± equaling tubular-funnelform throats, lobes 5, erect, deltate; style-branch appendages triangular. Cypselae subcylindro-fusiform, terete to ± flattened, 3–4-angled, faintly 10–12-nerved, faces sericeous to strigose or glabrous; pappi persistent, of 15–60 brownish, rigid, unequal, smooth, apically attenuate bristles in 1 series. x = 6.
w North America.
Species 14 (14 in the flora).
Pyrrocoma has often been treated as a section within genus Haplopappus (H. M. Hall 1928; A. Cronquist 1994). Various workers have suggested that Haplopappus be divided into a number of smaller genera such as Pyrrocoma, Tonestus, Stenotus, Chrysothamnus, and others. Pyrrocoma was recognized as a separate genus in the dissertation by R. A. Mayes (1976) and in a floristic treatment by G. K. Brown (1993b). It is characterized by its persistent basal rosettes, yellow-rayed heads on scapiform or few-bracteate peduncles, and obtuse, acute, or mucronate phyllaries. The heads vary greatly in size and commonly are sessile or subsessile and borne singly or in spiciform arrays. The base chromosome number of x = 6 is rare in Haplopappus in the broad sense, and supports recognition of a distinct genus (Mayes). Most species of Pyrrocoma are diploid, some tetraploid or hexaploid. The species are frequently polymorphic, and many subspecies and varieties have been named. Some of these taxa are only weakly characterized and their status needs clarification. The present treatment largely follows the works of Hall and Mayes.
|1||Heads disciform, subtended by leaflike bracts||> 2|
|1||Heads radiate, not subtended by leaflike bracts||> 3|
|2||Plants 5–50 cm; stems reddish, villous; basal leaf blades 5–40 mm wide, margins ciliate, faces puberulent; phyllaries in 3–5 series (± loose), unequal, margins ciliate, faces puberulent; British Columbia, nw United States||Pyrrocoma carthamoides|
|2||Plants 40–90 cm; stems pale, rarely reddish, glabrous; basal leaf blades 40–200 mm wide, margins eciliate, faces glabrous; phyllaries in 5–6 series, loosely appressed, unequal, margins eciliate, faces glabrous; Snake River canyon, Idaho, Oregon||Pyrrocoma radiata|
|3||Leaves glandular||> 4|
|3||Leaves eglandular||> 6|
|4||Glands sessile; stems not red-tinged, glabrous, resinous; basal leaf faces glabrous, gland-dotted; heads in crowded, spiciform arrays||Pyrrocoma lucida|
|4||Glands stipitate; stems red-tinged, hairy; basal leaf faces hairy; heads in corymbiform, racemiform, or paniculiform arrays||> 5|
|5||Stems villous, tomentose, or woolly; basal leaf faces villous to tomentose; heads in racemiform arrays||Pyrrocoma hirta|
|5||Stems ± tomentulose or glabrous; basal leaf faces tomentulose to glabrate or glabrous; heads in corymbiform or paniculiform arrays||Pyrrocoma lanceolata|
|6||Heads 3–20 (in racemiform, spiciform, corymbiform, or paniculiform arrays)||> 7|
|6||Heads 1–6+||> 10|
|7||Heads in corymbiform or paniculiform arrays||Pyrrocoma lanceolata|
|7||Heads in racemiform or spiciform arrays||> 8|
|8||Phyllaries in 2–3 series, (loose) linear-lanceolate, subequal||Pyrrocoma insecticruris|
|8||Phyllaries in 4–5 series, lanceolate to oblanceolate or oblong, unequal||> 9|
|9||Stems sparsely villous to tomentose; basal leaf faces sparsely tomen-tose; cypselae narrowly oblong||Pyrrocoma liatriformis|
|9||Stems usually glabrous, sometimes sparsely tomentulose or villous; basal leaf faces usually glabrous; cypselae subcylindric||Pyrrocoma racemosa|
|10||Involucres 20–60 mm wide; basal leaf blades broadly oblanceolate or spatulate to oblong, elliptic, or lanceolate, margins usually entire or undulate, sometimes dentate||> 11|
|10||Involucres 10–20 mm wide; basal leaf blades usually linear to lanceolate or narrowly oblanceolate, margins usually coarsely dentate to laciniate, rarely entire||> 13|
|11||Heads usually in racemiform arrays||Pyrrocoma integrifolia|
|11||Heads usually borne singly, sometimes 2–6||> 12|
|12||Plants usually 3–18 cm; stems usually sparsely villous, sometimes tomentose; basal leaf margins sparsely ciliate; phyllaries in 3–4 series, lanceolate to oblanceolate, unequal, margins ciliate, faces villous||Pyrrocoma clementis|
|12||Plants usually 18–80 cm; stems usually glabrous, often tomentose distally; basal leaf margins eciliate; phyllaries oblong to spatulate, subequal, margins eciliate, faces usually glabrous||Pyrrocoma crocea|
|13||Leaf faces glabrous; phyllaries in 3–4 series, oblanceolate to oblong, unequal, margins ciliate, faces glabrous; cypselae glabrous||Pyrrocoma apargioides|
|13||Leaf faces sericeous or shaggy-tomentose; phyllaries in 2 series, linear to linear-lanceolate, equal, margins ciliate, faces ±villous; cypselae sericeous||> 14|
|14||Leaf blades 2–5 mm wide (grasslike), margins usually entire||Pyrrocoma linearis|
|14||Leaf blades 3–20 mm wide, margins dentate to laciniate||Pyrrocoma uniflora|