Biennial herb; stem solitary, branching above the middle, 3-6 dm tall, glabrous or sparsely pubescent in the inflorescence; basal rosette leaves dying when the plant flowers; stem leaves numerous, pinnatifid with narrowly linear lobes; inflorescence corymbose (flat-topped); involucre of flower heads 5-8 mm tall, outer phyllaries united for 1/3 to 1/2 their length, inner phyllaries ciliate-margined and blunt to acute at the apex; flowers yellow, ray corollas usually shorter than the length of the involucre; achenes appressed-hairy, pappus scales acute to acuminate at the apex. Flowers late July to September.
Hymenoxys richardsonii is a strong perennial with more than one stem. Hymenoxys vaseyi is usually perennial with one or more stems, has ray corollas as long or longer than the involucre, outer phyllaries united for 1/2 to 2/3 their length, and pappus scales blunt at the apex.
New Mexico, northwestern Lincoln, northeastern Socorro, and western Torrance counties, southern Manzano Mountains, Gallinas Mountains, Los Pinos Mountains, and northern Chupadera Mesa.
Dry sites with coarse soils in piñon-juniper woodland and lower montane coniferous forest; 2,100-2,500 m (6,900-8,200 ft).
This narrow endemic is locally abundant and will sometimes occupy disturbed sites. The prevailing land uses within its habitats do not threaten this species.
Wooton, E.O. and P.C. Standley. 1913. Descriptions of new plants preliminary to a report upon the flora of New Mexico. Contributions from the U.S. National Herbarium 16:109-196.