Acmella

Richard

in C. H. Persoon, Syn. Pl. 2: 472. 1807.

Etymology: From a Singhalese name for a plant now known as Blainvillea acmella (Linnaeus) Philipson
Treatment appears in FNA Volume 21. Treatment on page 132. Mentioned on page 64, 65, 67.

Annuals or perennials, 10–20 (–30+) cm. Stems prostrate to erect, usually branched ± throughout. Leaves cauline; opposite; petiolate [± sessile]; blades (usually 3-nerved) ovate to rhombic or lanceolate [linear to filiform], bases ± cuneate, margins entire or toothed, faces sparsely pilose to strigillose, glabrescent. Heads radiate or discoid [disciform], borne singly at tips of branches [corymbiform arrays]. Involucres ± hemispheric to ovoid, 3–6+ mm diam. Phyllaries persistent, 8–15+ in 1–3 series (distinct, ovate to linear, subequal or outer longer). Receptacles conic, paleate (paleae falling with fruit, ± navicular, membranous to scarious, each about equaling subtended floret). Ray-florets 0 or 5–20+, pistillate, fertile; corollas yellow to orange [white or purplish] (laminae ovate to linear) [wanting]. Disc-florets 25–100 (–200+) bisexual, fertile; corollas yellow [orange], tubes shorter than campanulate throats, lobes 4–5, deltate. Cypselae 2–3-angled (peripheral) or strongly compressed, ellipsoid to obovoid (glabrous or ciliate on the 2–3 angles or ribs); pappi 0, or fragile, of 1–3 awnlike bristles. x = 13.

Distribution

s United States, Mexico, West Indies, Central America, South America, in Asia, Africa, Pacific Islands, Australia

Discussion

Species 30 (2 in the flora).

Acmella pilosa R. K. Jansen has been reported as introduced in Florida (http://www.plantatlas.usf.edu); it differs from A. repens mainly by its more densely pilose stems and leaves and more truncate to cordate (versus cuneate) leaf bases.

Key

1 Petioles 3–40+ mm; leaf blades ovate to lance-ovate, mostly 20–40(–100) × 10–35 mm, margins dentate to denticulate or entire Acmella repens
1 Petioles 2–4 mm; leaf blades lanceolate, mostly 12–40 × 3–10 mm, margins usually sinuate-dentate, rarely entire Acmella pusilla

"broader" is not a number.

... more about "Acmella"
not tailed +, rounded +  and obtuse +
connate +  and distinct +
subequal +
scarious +
usually ovate +  and lanceolate +
usually deltate +  and lanceolate +
spiciform +, racemiform +, paniculiform +, corymbiform +  and cymiform +
indeterminate +  and determinate +
John L. Strother +
Richard +
bristlelike +
coroniform +
cuneate +
compound +  and simple +
ovate;rhombic or lanceolate +
winged;ribbed;winged;ribbed +
tuberculate +  and rugose +
barbellulate +  and barbellate +
yellow +  and orange +
hairy +  and glabrous +
strongly compressed ellipsoid +  and obovoid +
fertile +  and bisexual +
fertile +  and bisexual +
s United States +, Mexico +, West Indies +, Central America +, South America +, in Asia +, Africa +, Pacific Islands +  and Australia +
From a Singhalese name for a plant now known as Blainvillea acmella (Linnaeus) Philipson +
glabrescent +, sparsely pilose +  and strigillose +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
discoid +  and radiate +
in cymiform , corymbiform , paniculiform , racemiform or spiciform , arrays +  and singly +
indeterminate +
homogamous +  and heterogamous +
each +  and sessile +
0.3 cm3 mm <br />0.003 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
less hemispheric;ovoid +
deltate +
dentate to pinnatifid or palmatifid +  and entire +
toothed +  and entire +
2-carpellate +
persistent +
8 +  and 15 +
unequal +  and subequal +
in C. H. Persoon, Syn. Pl. +
bearing subulate enations +, hairy +  and bristly +
jansen1985a +
exalbuminous +
prostrate +  and erect +
appendaged +  and truncate +
hirsutulous +  and glabrous +
papillate +
Undefined (tribe Undefined) subtribe Enceliinae +, Undefined (tribe Undefined) subtribe Engelmanniinae +, Undefined (tribe Undefined) subtribe Spilanthinae +, Undefined (tribe Undefined) subtribe Verbesininae +  and Undefined (tribe Undefined) subtribe Zinniinae +
Acmella +
Asteraceae (tribe Heliantheae) subtribe Ecliptinae +
campanulate +
cylindric +
shorter to longer than campanulate +
toothed +  and entire +
20 cm200 mm <br />0.2 m <br /> (30 cm300 mm <br />0.3 m <br />) +
perennial +  and annual +
10 cm100 mm <br />0.1 m <br /> (20 cm200 mm <br />0.2 m <br />) +
shrub +  and subshrub +