Smallhead heathgoldenrod

Haplopappus microcephalus Cronquist, Madroño 11: 186. 1951; Tonestus microcephalus (Cronquist) G. L. Nesom & D. R. Morgan

Subshrubs, 5–20 cm (mat-forming); caudices woody. Stems 3–20+ (erect), green, simple (± ridged), sparsely stipitate-glandular, resinous. Leaves cauline, crowded near base of current year growth, mostly ascending; blades with midnerves prominent usually plus 2 evident, collateral veins, elliptic to narrowly oblanceolate, 20–40 × 2–3.5 mm, flat to ± concave adaxially, margins entire, scarious, stipitate-glandular, apices acute, faces usually glabrous or stipitate-glandular, adaxially pustulate, gland-dotted and resinous along major nerves. Heads in corymbiform arrays 1–4 cm wide. Involucres obconic to subhemispheric, 6–8 mm. Phyllaries 24–30 in 3–4 series, green to tan, midnerves evident, ovate or lanceolate to elliptic, 3.5–7 × 0.7–1.3 mm, subequal, herbaceous or herbaceous-tipped (outer), usually chartaceous (inner), usually flat to convex, margins narrowly scarious, sometimes sparsely ciliate, apices attenuate to cuspidate (outer), acuminate to acute (inner), faces glabrous, resinous. Receptacles without scales. Ray florets 5–8; laminae elliptic to narrowly obovate, 3.5–5 × ca. 1 mm. Disc florets 10–15; corollas 4.3–4.7 mm, glabrous, lobes 0.5–1 mm; style branches exserted, ca. 2.5 mm, appendages lanceolate, ca. 1.7 mm. Cypselae tan, oblong, 1.5–2.3 mm, 5–7 ribbed, faces moderately hairy; pappi tan (fine, barbellate), 3–5 mm. 2n = 18.

Flowering late summer–fall. Thin soils or cracks on granite outcrops; of conservation concern; 2400–2700 m; Colo., N.Mex.