''Tanacetum cinerariifolium'' is a species of

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants t ...

in the aster family,

Asteraceae The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae ...

, and formerly part of the genus ''

Pyrethrum ''Pyrethrum'' was a genus of several Old World plants now classified as ''Chrysanthemum'' or ''Tanacetum'' which are cultivated as ornamentals for their showy flower heads. Pyrethrum continues to be used as a common name for plants formerly inclu ...

'', but now placed in the genus ''

Chrysanthemum Chrysanthemums (), sometimes called mums or chrysanths, are flowering plants of the genus ''Chrysanthemum'' in the family Asteraceae. They are native to East Asia and northeastern Europe. Most species originate from East Asia and the cent ...

'', or the genus ''

Tanacetum ''Tanacetum'' is a genus of about 160 species of flowering plants in the aster family, Asteraceae, native to many regions of the Northern Hemisphere.

'' by some biologists. It is called the Dalmatian chrysanthemum, denoting its origin in that region of Europe (Dalmatia). It looks more like the common daisy than other pyrethrums do. Its flowers, typically white with yellow centers, grow from numerous fairly rigid stems. Plants have blue-green leaves and grow to 45 to 100 cm (18 to 39 in) in height.

As an insecticide

The plant is economically important as a natural source of an insecticide called "pyrethrum." The flowers are pulverized and the active components, called

pyrethrins The pyrethrins are a class of organic compounds normally derived from '' Chrysanthemum cinerariifolium'' that have potent insecticidal activity by targeting the nervous systems of insects. Pyrethrin naturally occurs in chrysanthemum flowers and i ...

, contained in the seed cases, are extracted and sold in the form of an oleoresin. This is applied as a suspension in water or oil, or as a powder. Pyrethrins attack the nervous systems of all insects, and inhibit female mosquitoes from biting. When present in amounts less than those fatal to insects, they still appear to have an insect repellent effect. They are harmful to fish, but are far less toxic to mammals and birds than many synthetic insecticides and are not persistent, being biodegradable and also decompose easily on exposure to light. They are considered to be amongst the safest insecticides for use around food. Kenya produced 90% (over 6,000 tonnes) of the world's pyrethrum in 1998, called py for short. Production in Tanzania and Ecuador is also significant. Currently the world's major producer is Australia. The plant is also used in companion planting. See .

Safety

These plants can cause severe allergic reactions in some people. Prolonged contact with the dried flowers can cause allergic dermatitis, allergic rhinitis, and asthma.

References

cinerariifolium Flora of Europe {{Anthemideae-stub

As an insecticide

Safety

See also

References