Parthenium confertum
Proc. Amer. Acad. Arts 17: 216. 1882.
Biennials (sometimes flowering first-year or persisting), 10–30 (–60+) cm. Leaf-blades ovate or rounded-deltate to elliptic, 30–80 (–120+) × 10–20 (–40+) mm, usually ± pinnately or sub-bipinnately lobed, ultimate margins entire, faces strigillose, usually also with erect hairs 1–2 mm and glanddotted. Heads disciform or obscurely radiate, borne in open, ± paniculiform arrays. Peduncles 2–8 (–12+) mm. Phyllaries: outer 5 lanceovate to elliptic, 2.5–3+ mm, inner 5 ± orbiculate, 3–3.5 mm. Pistillate florets 5; corolla laminae 0 or ± coroniform, 0.1–0.5 mm. Disc-florets 20–30+. Cypselae ± obovoid, 2–3 mm; pappuslike enations 2, ± erect, deltate to ovate, 0.5–1 mm (sometimes a third, subulate spur near apex adaxially). 2n = 36, 68, 72.
Phenology: Flowering Mar–Oct.
Habitat: Sandy plains, openings in mesquite grasslands
Elevation: 20–2000 m
Distribution
Ariz., N.Mex., Tex., Mexico
Discussion
Selected References
None.