Annuals, 5-50 cm. Leaves 5-40 × 3-17 mm. Involucres broadly turbinate, 5-10 mm. Phyllaries 24-44 in 3-5 series, lanceolate to linear-lanceolate, 4-9 × 0.7-1.5 mm, apices usually appressed, sometimes spreading, acute to acuminate. Receptacles convex, 2-3.5 mm diam. Ray florets 8-16; laminae 6-15 × 1-3 mm. Disc florets 14-40(-45); corollas 4-7 mm, glabrous or glabrate; lobes 0.7-1 mm, hairy (hairs multicellular), 0.2-0.5 mm. Cypselae 2-3.5(-4) mm; pappi 2-8 mm. 2n = 8.
Flowering Jul-Oct(-Dec). Grasslands, Larrea-dominated desert scrub, pine-oak woodlands, roadsides, streambeds; 700-1700(-2200) m; Ariz., N.Mex.; Mexico (Chihuahua, Sonora).
In the flora area, Machaeranthera tagetina occurs in southern and central Arizona and southwestern New Mexico, in the Chihuahuan and Sonoran desert regions. Much of its range in those states overlaps with that of M. tanacetifolia. In southern and central Arizona, the two species occasionally hybridize.
Duration: Annual
Nativity: Native
Lifeform: Forb/Herb
General: Annual, or possibly biennial under favorable conditions, stems slender, moderately branched, 10-40 cm long, puberulent with both eglandular and gland-tipped hairs, slightly cinereous.
Leaves: Lower leaves pinnatifid, 1.5-2.5 cm long, 3-7 lobes acute, spinulose-tipped, .5-3 mm broad, 2-6 mm long, upper leaves reduced and denticulate, all hirsutulous and glandular-puberulent.
Flowers: Stems leafy to heads, these 10-15 mm wide, bracts lance-linear, 3-8 mm long, green herbaceous part triangular to lance-triangular, nearly as wide as papery part, densely glandular; rays 10-20, ligules 2-2.5 mm wide, 6-7 mm long, purplish; disk corollas 6-6.5 mm long, slender, slightly and gradually ampliate, glabrous.
Fruits: Cypselae about 4 mm long, silky-villous; pappus bristles slender, 5-6 mm long, whitish.
Ecology: Found on arid mesas, plains, and roadsides from 1,500-4,500 ft (457-1372 m); flowers from April-October.
Ethnobotany: Unknown for this species, other species in this genus have limited use.
Etymology: Machaeranthera comes from the Greek machaira, meaning sword and anthera or anthers, referring to the shape of the anther-tips, while tagetina refers to the genus Tagetes.
Synonyms: Aster tagetinus
Editor: SBuckley, 2010
