Asteraceae (tribe Heliantheae) subtribe Dimeresiinae

Annuals, 1–3(–5) cm. Leaves basal and/or cauline; opposite (crowded); subsessile or ± petiolate; blades oblanceolate to spatulate, margins entire, faces tomentose to glabrescent, often gland-dotted. Heads discoid, usually (2–5) in congested clusters (clusters often crowded, total heads top 100+). Calyculi 0. Involucres cylindric to obconic. Phyllaries persistent, 2–3 in 1 series (oblong, subequal, herbaceous, basally connate or distinct). Receptacles flat (minute), epaleate. Ray florets 0. Disc florets 2–3, bisexual, fertile; corollas white, pink, or purple, tubes shorter than funnelform throats, lobes 5, deltate-ovate; anther thecae pale; stigmatic papillae in 2 lines. Cypselae cylindric to clavate, fine-ribbed, glabrous; pappi soon falling (all together), of ca. 20, basally connate, setiform to subulate, ± plumose scales (or flattened bristles).

Distribution

w United States.

Discussion

Genus 1, species 1.

The sole genus of Dimeresiinae was originally placed in a broadly circumscribed Inuleae. H. Robinson (1981) suggested possible relationships with Galinsoginae and/or Helianthinae. B. G. Baldwin et al. (2002) positioned Dimeresia in Chaenactideae with Chaenactis and Orochaenactis as the other two genera in the tribe.

Selected References

None.

Lower Taxa

Dimeresia