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(Last Modified On 6/19/2013)
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(Last Modified On 6/19/2013)
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Genus
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Chrysanthemum L.
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PlaceOfPublication
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Sp. P1. 887. 1753
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Note
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TYPE: C. coronarium L.
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Synonym
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Leucanthemum Lam., Fl. Francoise 2: 136. 1778. TYPE: L. vulgare L.
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Description
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Mostly erect and branched annual or perennial herbs, rarely shrubs, often strong scented. Leaves alternate, entire to much dissected, glabrate or sometimes pubescent. Inflorescence of solitary heads or paniculate, cymose or solitary, the heads long stalked. Heads mostly conspicuously radiate, rarely discoid, with many florets, variously colored, often showy; involucral bracts narrow in 3-4 similar but unequal series, the costa darkened with a hyaline, often brownish margin, at least at the tips; receptacle flat or convex; paleas present or not; ray florets in one or many series, the ligule entire or dentate, the tube terete, flattened or rarely winged, larger at the base, the ovary mostly fertile; disc florets numerous, the corolla mostly yellowish with little distinction between tube and limb, apically (4-) 5-dentate, the anthers basally obtuse or truncate, apically appendaged, the style sometimes basally enlarged, the branches with a ventral groove and flat and fringed at the truncate, sometimes expanded apex, the ovary mostly like that of the ray floret but less compressed, or sometimes shrivelled and sterile. Achene mostly dorsiventrally flattened, sometimes 3-angled or winged, mostly with 5-10 prominent regular sulci or nerves; carpopodium inconspicuous; pappus wanting or an interrupted ring of scales.
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Habit
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herbs
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Distribution
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Chrysanthemum is sometimes interpreted narrowly to include about 5 species of Europe and the Mediterranean region, or sometimes broadly to include over 200 species widely dispersed in the Old World.
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Note
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In Panama, the genus is distinct in its aromatic foliage, broad rays, and achenes with conspicuous, evenly spaced nerves or sulci. It is known here only by two cultivated and sometimes escaping Old World species. Plants in this genus are mostly aromatic and have been used in folk medicine in a number of countries. Contact with the leaves may cause dermatitis. Two species (not in Panama) are used for insecticides known as pyrethrins or Dalmation powder.
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Key
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a. Heads more than 25 mm across; leaves of the stem remotely denticulate, eglandular beneath; plants mostly exceeding 70 cm tall; scaly pappus well developed ...... 1. C. leucanthemum aa. Heads less than 20 mm across; leaves of the stem saliently toothed, copiously glandular beneath; plants seldom exceeding 60 cm tall; pappus rudimentary (scaly) or wanting ...... 2. C. parthenium
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