Asteraceae (tribe Heliantheae) subtribe Dimeresiinae

H. Robinson

Phytologia 41: 40. 1978.

Treatment appears in FNA Volume 21. Treatment on page 182. Mentioned on page 5, 364.

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 glanddotted. 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

not tailed +, rounded +  and obtuse +
connate +  and distinct +
subequal +
scarious +
usually ovate +  and lanceolate +
usually deltate +  and lanceolate +
spiciform +, racemiform +, paniculiform +  and corymbiform +
indeterminate +  and determinate +
Theodore M. Barkley† +, Luc Brouillet +  and John L. Strother +
H. Robinson +
decurrent +
compound +  and simple +
oblanceolate;spatulate +
winged;ribbed;winged;ribbed +
tuberculate +  and rugose +
barbellulate +  and barbellate +
purple +, pink +  and white +
cylindric +  and clavate +
fertile +  and bisexual +
fertile +  and bisexual +
w United States +
tomentose +  and glabrescent +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
indeterminate +
homogamous +  and heterogamous +
each +  and sessile +
cylindric;obconic +
petiolate +  and subsessile +
cauline +  and basal +
deltate-ovate +
2-carpellate +
persistent +
styliferous +, neuter +  and pistillate +
bearing subulate enations +, hairy +  and bristly +
flat;conic or cylindric +
plumose +, setiform +  and subulate +
exalbuminous +
prostrate +  and ascending +
appendaged +  and truncate +
hirsutulous +  and glabrous +
papillate +
Compositae +
Asteraceae (tribe Heliantheae) subtribe Dimeresiinae +
Asteraceae tribe Heliantheae +
subtribe +
3 cm30 mm <br />0.03 m <br /> (5 cm50 mm <br />0.05 m <br />) +
1 cm10 mm <br />0.01 m <br /> (3 cm30 mm <br />0.03 m <br />) +
tree +, shrub +  and subshrub +