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(Last Modified On 6/14/2013)
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(Last Modified On 6/14/2013)
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Genus
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Polymnia L.
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PlaceOfPublication
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Sp. P1. 926. 1753
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Note
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TYPE: P. canadensis L.
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Description
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Erect, perennial herbs to trees more than 12 m tall; stems terete, angular or canaliculate, to 20 cm diam., the bark on large stems becoming rough. Leaves opposite (upper leaves sometimes subopposite); blades entire to deeply lobed, pinnately or palmately veined; sessile or petiolate, the petioles sometimes winged. Inflorescence of one to many heads. Heads radiate; involucre with bracts usually 4-6 in 1-2 series, the innermost bracts concave and at maturity partially enclosing the ray achenes, acuminate; receptacle flat or somewhat to decidedly convex; paleas usually chartaceous or infrequently of firmer texture and subulate, with or without prominent veins; ray florets in 1 or rarely 2 series, fertile, the corollas 2-3-lobed or entire, yellow, white or orange-red; disc florets perfect and sterile, the corollas yellow or sometimes purplish (when dry), the ovary sterile. Achenes brown, purplish-black or black, obovoid or spherical and slightly flattened laterally, sometimes 3-5-angled, the angles infrequently winged, to 7 mm long;
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Habit
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herbs to trees
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Description
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pappus absent. Chromosome numbers n = 14, 15, 16, 17, ca. 20, over 25, ca. 29, 30, 33 ? 1 fragment.
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Distribution
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This is a genus of 20 species distributed over both North and South America (Guianas excepted) in generally temperate regions.
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Note
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Polymnia can be distinguished from other genera of the Melampodiinae by its large, black fruits.
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Reference
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Wells, J. R. 1965. A taxonomic study of Polymnia (Compositae). Brittonia 17: 144-159.
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