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(Last Modified On 6/18/2013)
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(Last Modified On 6/18/2013)
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Genus
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Chrysanthellum L. C. Rich.
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PlaceOfPublication
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Syn. P1. 2: 1807.
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Note
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TYPE: C. procumbens L. C. Rich. = C. americanum (L.) Vatke.
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Synonym
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Microlecane Schultz-Bip. ex Benth. & Hook., Gen. P1. 2: 384. 1873. TYPE: M. abyssinica Schultz-Bip. = Chrysanthellum americanum (L.) Vatke. Chrysanthellina Cass., Dict. Sci. Nat. 25: 390. 1822, orth. mut. Chrysanthellum L. C. Rich. Collaea Spreng., Syst. Veg. 3: 622. 1826. TYPE: C. procumbens (L. C. Rich.) Spreng. Sebastiana Bertol., -Lucubr. 37. 1822. TYPE: S. heterophylla Bertol. = Chrysanthellum americanum (L.) Vatke.
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Description
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Diminutive, short-lived herbs, erect, prostrate or ascending with a short, slender tap root. Leaves alternate or opposite, entire, dentate to bipinnately dissected with fine divisions, glabrate; the petiole slender, sometimes not distinguished from the blade, slightly clasping the stem. Inflorescence of solitary ascending flowers or rarely clustered in an ill-defined panicle; peduncle slender, glabrate, often with foliaceous or scalelike bracts. Heads radiate; involucral bracts in 2-3 dissimilar series, the outer bracts few, short, linear to lanceolate and conspicuously basally thickened, the inner series similar, imbricate, the innermost sometimes slightly narrower, imbricate, oblong to lanceolate, indurate or chartaceous, drying striate, the hyaline margins broad, entire; receptacle hemiglobose; paleas mostly persistent, linear with a dark costa and hyaline margins, the outermost half enfolding the ray ovaries; ray florets several in ca. 2 series, the corolla yellow with a short tube and two distinct longitudinal ribs, apically 2(3)-denticulate, the ovary laterally flattened, epappose; disc florets several, the corolla campanulate, the 5 lobes enervate, glabrous, the anthers dark with deltoid, uncolored appendages, basally obtuse or subauriculate, the style branches with flattened, pilose margins. Achenes often dimorphic, the outermost oblong, buff, tuberculate, sometimes puberulent, the apex slightly expanded into two lateral ears, the innermost flat, black, with massive, light-colored wings; pappus wanting.
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Habit
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herbs
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Distribution
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a genus of perhaps 6 species in the tropics of both the New and Old Worlds.
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Note
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The dimorphic involucral bracts, and the prominently winged, epappose, central fruits are distinctive. This is a genus where the term palea requires broad definition, for the bracts enfolding the ray ovaries and those subtending the disc ovaries are alike but different from the two types of involucral bracts.
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