Wrightia 1: 77. 1946.
Annuals, 1–3 cm, eglandular; usually taprooted, rarely producing slender caudex branches when buried. Leaves not densely overlapping, basal blades oblanceolate-spatulate, cauline mostly oblanceolate to narrowly oblanceolate, 5–20 (–30) × 2–5 mm, herbaceous, bases not clasping, flat, faces strigose. Involucres hemispheric, 3.5–6 × 4–10 mm. Ray-florets 10–20 (–32); corollas white. Disc-florets 33–106, bisexual. Cypselae 1.8–2.1 mm, 2 (–3) -nerved, faces sparsely strigose; pappi in 2 series, outer of (4–) 5 (–8) broad, white, hyaline scales 1–1.5 mm plus alternating inner of (4–) 5 (–8), barbellate bristles 2.1–3 mm. 2n = 16, 32.
Phenology: Flowering May(–Sep, –Nov).
Habitat: Limestone outcrops and roadcuts, juniper and oak woodlands
Elevation: 100–900 m
Tex., Mexico (Aguascalientes), Mexico (Chihuahua), Mexico (Coahuila), Mexico (Durango), Mexico (Nuevo León), Mexico (San Luis Potosí), Mexico (Tamaulipas), Mexico (Zacatecas)
Chaetopappa bellioides is distinct in growth habit: numerous ascending stems usually arise from the apex of the caudex and form a bowl-like shape. Branches in other Chaetopappa species mostly arise above the base of the stem.
"thick" is not a number.