/rag"weed'/, n.
any of the composite plants of the genus Ambrosia, the airborne pollen of which is the most prevalent cause of autumnal hay fever, as the common North American species, A. trifida (great ragweed or giant ragweed) and A. artemisiifolia.
[1650-60; RAG1 + WEED1, so called from its ragged appearance]

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Any of about 15 species of weedy plants (see weed) that make up the genus Ambrosia in the composite family, most of which are native to North America.

They have rough hairy stems, mostly lobed or divided leaves, and inconspicuous greenish flowers borne in small heads. Common ragweed (A. artemisiifolia) is found across North America. Pollen shed by ragweeds in great abundance in late summer is the principal cause of hay fever in eastern and middle North America. Since ragweeds are annuals, mowing before pollination season eradicates them.

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▪ plant genus
 (genus Ambrosia), any of a group of about 40 species of weedy plants of the family Asteraceae. Most species are native to North America. The ragweeds are coarse annuals with rough hairy stems, mostly lobed or divided leaves, and inconspicuous greenish flowers that are borne in small heads, the male in terminal spikes and the female in the upper axils of the leaves. The common ragweed (A. artemisiifolia), also called Roman wormwood, hogweed, hogbrake, and bitterweed, is found across the North American continent. It typically grows about 1 metre (3.5 feet) high and has thin, alternate or opposite, much-divided leaves. The great, or giant, ragweed (A. trifida), also called bitterweed, or horse cane, is native from Quebec to British Columbia and southward to Florida, Arkansas, and California. It grows from 0.9 to 5 metres (3 to 17 feet) high and has three- to five-lobed leaves.

      Both the common and great ragweed are annuals and often become pernicious weeds; their pollen, which is shed in great abundance in late summer, is the principal cause of hay fever in eastern and middle North America. Since these species are annuals, their eradication is easy if they are mowed well before they shed their copious pollen.

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Universalium. 2010.

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Look at other dictionaries:

  • Ragweed — Rag weed (r[a^]g w[=e]d ), n. (Bot.) A common American composite weed ({Ambrosia artemisi[ae]folia}) with finely divided leaves; hogweed. [1913 Webster] {Great ragweed}, a coarse American herb ({Ambrosia trifida}), with rough three lobed opposite …   The Collaborative International Dictionary of English

  • ragweed — (n.) 1790, from RAGGED (Cf. ragged) + WEED (Cf. weed) (n.); so called from shape of the leaves. Applied to a different plant, ragwort, from 1650s. Ragwort itself is attested from mid 15c. (see WORT (Cf. wort)) …   Etymology dictionary

  • ragweed — ☆ ragweed [rag′wēd΄] n. [from the tattered appearance of the leaves ] any of a genus (Ambrosia) of chiefly North American plants of the composite family, having tassel like, greenish flowers which yield large amounts of wind borne pollen, a major …   English World dictionary

  • Ragweed — Taxobox name = Ragweeds image width = 200px image caption = A ragweed, Ambrosia sp. regnum = Plantae divisio = Magnoliophyta classis = Magnoliopsida subclassis = Asteridae unranked ordo = Euasterids II ordo = Asterales familia = Asteraceae… …   Wikipedia

  • ragweed — kietinė ambrozija statusas T sritis vardynas apibrėžtis Astrinių šeimos vaistinis nuodingas augalas (Ambrosia artemisiifolia), paplitęs Šiaurės Amerikoje. atitikmenys: lot. Ambrosia artemisiifolia angl. annual ragweed; bitterweed; common ragweed; …   Lithuanian dictionary (lietuvių žodynas)

  • Ragweed — Any of a number of weedy composite herbs that produce a pollen that is a frequent cause of allergies. Of all allergy sufferers in the United States, 75% are allergic to ragweed. * * * rag·weed rag .wēd n any of various chiefly No. American weedy… …   Medical dictionary

  • ragweed — /ˈrægwid/ (say ragweed) noun 1. any of the herbs constituting the genus Ambrosia, whose airborne pollen is a cause of hay fever, as the common ragweed, A. artemisiifolia. 2. → ragwort. {rag1 + weed1} …  

  • ragweed — n. inferior marijuana. (Drugs.) □ This stuff is ragweed. You can have it! □ Bart just sells ragweed except to his friends …   Dictionary of American slang and colloquial expressions

  • Ragweed — Beifußblättriges Traubenkraut Beifußblättriges Traubenkraut (Ambrosia artemisiifolia) Systematik Ordnung …   Deutsch Wikipedia

  • ragweed pollen — noun pollen of the ragweed plant is a common allergen • Hypernyms: ↑pollen, ↑allergen …   Useful english dictionary

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