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Acmella biflora

Interesting Facts

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Description

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Family Compositae

The largest family of flowering plants , the Compositae (Asteraceae), comprising about 1,100 genera and more than 20,000 species and characterized by many small flowers arranged in a head looking like a single flower and subtended by an involucre of bracts. A head may consist of both ray flowers and disk flowers, as in the sunflower, of disk flowers only, as in the burdock, or of ray flowers only, as in the dandelion.

Tribe Heliantheae

The Heliantheae are a tribe of closely related genera of the sunflower family that can be readily recognized due to the association of a receptacular bract or chaff scale with each disk floret in the head . The heads usually include bisexual , actinomorphic disk florets with tubular corollas that have 4 or 5 distal lobes and also peripheral zygomorphic female or sometimes sterile florets with strap-shaped corollas that have 3 or fewer distal teeth. However, the ray flowers are sometimes absent and the heads are then discoid , containing only bisexual florets with tubular corollas. The pappus is absent or more commonly ranges from scales to stiff bristles . -- Gerald Carr.

Genus Acmella

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.

Species 30: s United States, Mexico, West Indies, Central America, South America; introduced in Asia, Africa, Pacific Islands, Australia.

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.[1]

Taxonomy

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Synonyms

Melanthera Biflora • Melanthera biflora (L.) Wild • Verbesina Biflora • Verbesina biflora L. • Wedelia biflora< /i> (L.) Dc. • Wollastonia biflora< /i> (L.) Dc.

Notes

Publishing author : Spreng. Publication : Syst. iii. 591

Similar Species

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Members of the genus Acmella

ZipcodeZoo has pages for 8 species, subspecies, varieties, forms, and cultivars in this genus:

A. decumbens (Creeping Spotflower) · A. iodiscaea (Maluco) · A. oleracea (Perennial Para Cress) · A. oppositifolia (Oppositeleaf Spotflower) · A. oppositifolia var. repens (Oppositeleaf Spotflower) · A. paniculata (Panicled Spot Flower) · A. pilosa (Hairy Spotflower) · A. pusilla (Dwarf Spotflower)

More Info

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Further Reading

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Notes

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Contributors

Identifiers

Footnotes

  1. John L. Strother "Acmella". in Flora of North America Vol. 21 Page 64, 65, 67, 132. Oxford University Press. Online at EFloras.org. [back]
Last Revised: 7/22/2012