pyrethrum


pyrethrum
/puy ree"threuhm, -reth"reuhm/, n.
1. any of several chrysanthemums, as Chrysanthemum coccineum, having finely divided leaves and showy red, pink, lilac, or white flowers, cultivated as an ornamental.
2. any of several chrysanthemums, as C. cinerariifolium, or C. coccineum, cultivated as a source of insecticides.
3. Pharm. the dried flower heads of these plants, used chiefly as an insecticide and sometimes in medicine for certain skin disorders.
[1555-65; < L: pellitory < Gk pýrethron, akin to pyretós fever; cf. PELLITORY]

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Any of certain plant species of the genus Chrysanthemum (see chrysanthemum) native to South Asia, whose aromatic flower heads, when powdered, constitute the active ingredient in the insecticide pyrethrin (or pyrethrum).

The concentrations of pyrethrum powder used in insecticides are nontoxic to plants and higher animals; these insecticides therefore find wide use in household and livestock sprays as well as in dusts for edible plants. The typical species, the perennial C. coccineum, also is the florists' pyrethrum, or painted lady. Large petals of a deep rose colour surrounding the yellow centre, or disk, are borne on long simple stems above the crown of finely cut leaves.

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plant
      any of certain plant species of the genus Tanacetum, native to southwestern Asia, whose aromatic flower heads, when powdered, constitute the active ingredient in the insecticide called pyrethrin, or pyrethrum. The plants were formerly considered a separate genus, Pyrethrum. The typical species, the perennial T. coccineum, is the florists' pyrethrum, commonly called painted lady. Large deep rose-coloured petals surrounding the yellow centre, or disk, are borne on long simple stems above the crown of finely cut leaves. Modern varieties exhibit various colours—white, lilac, and shades of red.

      The powdered flower heads of T. coccineum, T. cinerariifolium, and T. marschalli are chief sources of the insecticide. The active substances in pyrethrum are contact poisons for insects and cold-blooded vertebrates. The concentrations of pyrethrum powder used in insecticides are nontoxic to plants and higher animals; therefore, these insecticides find wide use in household and livestock sprays as well as in dusts for edible plants.

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Universalium. 2010.

Look at other dictionaries:

  • Pyrethrum — ist ein Insektizid, das aus den Blüten von verschiedenen Tanacetum Arten gewonnen wird. Die Hauptwirkstoffe sind Pyrethrine, außerdem Cinerine und Jasmoline. Inhaltsverzeichnis 1 Herstellung 2 Anbau 3 Wirtschaftliche Bedeutung …   Deutsch Wikipedia

  • Pyrethrum — refers to several Old World plants of the genus Chrysanthemum (e.g., C. coccineum ) which are cultivated as ornamentals for their showy flower heads. It is also the name of a natural insecticide made from the dried flower heads of C.… …   Wikipedia

  • Pyrethrum — Saltar a navegación, búsqueda Pyrethrum puede referirse a: El nombre común de la planta Chrysanthemum cinerariaefolium El sinónimo del género botánico Tanacetum Obtenido de Pyrethrum Categoría: Wikipedia:Desambiguación …   Wikipedia Español

  • Pyrethrum — (P. Gärtn.), aus mehren Arten von Chrysanthemum gebildete Pflanzengattung aus der Familie der Compositae Senecionideae Anthemideae, 19. Kl. 2. Ordn. L.; Arten: P. Myroni, mit gelben Blüthen; P. indicum, in China, Japan, Ostindien, strauchartig,… …   Pierer's Universal-Lexikon

  • Pyrethrum — Pyrethrum, s. Chrysanthemum …   Meyers Großes Konversations-Lexikon

  • Pyrethrum — Pyrĕthrum, Pflanzenart, s. Chrysanthemum …   Kleines Konversations-Lexikon

  • pyrethrum — ► NOUN 1) an aromatic plant of the daisy family, typically with brightly coloured flowers. 2) an insecticide made from the dried flowers of these plants. ORIGIN Greek purethron feverfew …   English terms dictionary

  • pyrethrum — [pī reth′rəm, pīrē′thrəm] n. [ModL < L < Gr pyrethron, feverfew < pyr, FIRE] 1. a perennial plant (Chrysanthemum coccineum) of the composite family, widely grown for the white, pink, red, or purple flower heads 2. an insecticide made… …   English World dictionary

  • Pyrethrum — Py|re|thrum auch: Py|reth|rum 〈n.; s, re|thra〉 aus Wucherblumen (Chrysanthemen) gewonnenes Insektengift [<grch. pyrethron; zu pyr „Feuer“] * * * Py|re|th|rum, das; s, …ra [griech. pýrethron = Mauerkraut, zu: pỹr ↑ (pyro , Pyro ), wohl wegen… …   Universal-Lexikon

  • Pyrethrum — Pyrèthre Pyrèthre …   Wikipédia en Français


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