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23-418: Some members of the genus Chrysanthemum , such as the following two, are placed in the genus Tanacetum instead by some botanists. Both genera are members of the daisy (or aster) family, Asteraceae . They are all perennial plants with a daisy-like appearance and white petals . The flowers are pulverized and the active components, called pyrethrins, contained in the seed cases, are extracted and sold in

46-632: A counterclockwise pattern. Hurricanes and tropical storms (massive low-pressure systems) spin counterclockwise in the Northern Hemisphere. The shadow of a sundial moves clockwise on latitudes north of the subsolar point and anticlockwise to the south. During the day at these latitudes, the Sun tends to rise to its maximum at a southerly position. Between the Tropic of Cancer and the Equator,

69-400: Is immediately dangerous to life and health . People exposed to pyrethrum may experience symptoms including pruritus (itching), dermatitis , papules , erythema (red skin), rhinorrhea (runny nose), sneezing , and asthma . Pyrethrum, specifically the pyrethrin within, is highly toxic to insects including useful pollinators like bees. The risk of killing bees and other beneficial insects

92-555: Is a genus of about 160 species of flowering plants in the aster family, Asteraceae , native to many regions of the Northern Hemisphere . They are known commonly as tansies . The name tansy can refer specifically to Tanacetum vulgare , which may be called the common tansy or garden tansy for clarity. The generic name Tanacetum means 'immortality' in Botanical Latin , since tansy was once placed between

115-615: Is a ribbed, glandular cypsela , usually with a pappus on the end. Species include: Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the Equator . For other planets in the Solar System , north is defined as being in the same celestial hemisphere relative to the invariable plane of the Solar System as Earth's North Pole . Due to Earth's axial tilt of 23.439281°, there

138-568: Is a seasonal variation in the lengths of the day and night. There is also a seasonal variation in temperatures, which lags the variation in day and night. Conventionally, winter in the Northern Hemisphere is taken as the period from the December solstice (typically December 21 UTC ) to the March equinox (typically March 20 UTC), while summer is taken as the period from the June solstice through to

161-482: Is partially reduced by the compound's rapid breakdown (a half-life of approximately 12 hours on plants and on the surface of the soil, with about 3% remaining after five days, but persisting several weeks or more if it enters a body of water or is dug into the soil) and its slight insect-repellant activity. Common names for Chrysanthemum cinerariifolium include: Common names for Chrysanthemum coccineum include: Tanacetum About 160, see text Tanacetum

184-570: The Coriolis effect . The currents then bend to the right, heading north. At about 30 degrees north latitude, a different set of winds, the westerlies , push the currents back to the east, producing a closed clockwise loop. Its surface is 60.7% water, compared with 80.9% water in the case of the Southern Hemisphere , and it contains 67.3% of Earth's land. The continents of North America and mainland Eurasia are located entirely in

207-465: The Northern temperate zone . The changes in these regions between summer and winter are generally mild, rather than extreme hot or cold. However, a temperate climate can have very unpredictable weather. Tropical regions (between the Tropic of Cancer and the Equator, 0° latitude) are generally hot all year round and tend to experience a rainy season during the summer months, and a dry season during

230-547: The September equinox (typically on 23 September UTC). The dates vary each year due to the difference between the calendar year and the astronomical year . Within the Northern Hemisphere, oceanic currents can change the weather patterns that affect many factors within the north coast. Such events include El Niño–Southern Oscillation . Trade winds blow from east to west just above the equator. The winds pull surface water with them, creating currents, which flow westward due to

253-504: The burial sheets of the dead to repel vermin. Other familiar species include costmary ( T. balsamita ) and feverfew ( T. parthenium ). Tansies are mainly perennial herbs, but some are annuals and subshrubs. Some are a few centimeters tall and some reach 1.5 metres (4 ft 11 in). They vary in form, with one or more branching stems growing erect or prostrate, usually from rhizomes . They are hairy to hairless in texture, and most are aromatic. The leaves are alternately arranged,

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276-583: The last glacial period ended about 10,000 years ago. Earth is currently in an interglacial period of the Quaternary , called the Holocene . The glaciations that occurred during the glacial period covered many areas of the Northern Hemisphere. The Arctic is a region around the North Pole (90° latitude ). Its climate is characterized by cold winters and cool summers. Precipitation mostly comes in

299-630: The Northern Hemisphere, together with about two-thirds of Africa and a small part of South America . During the 2.5 million years of the Pleistocene , numerous cold phases called glacials ( Quaternary ice age ), or significant advances of continental ice sheets, in Europe and North America , occurred at intervals of approximately 40,000 to 100,000 years. The long glacial periods were separated by more temperate and shorter interglacials which lasted about 10,000–15,000 years. The last cold episode of

322-734: The Sun can be seen to the north, directly overhead, or to the south at noon, depending on the time of year. In the Southern Hemisphere, the midday Sun is predominantly in the north. When viewed from the Northern Hemisphere, the Moon appears inverted compared to a view from the Southern Hemisphere. The North Pole faces away from the Galactic Center of the Milky Way . This results in the Milky Way being sparser and dimmer in

345-441: The animal's body weight required to cause significant mortality. This is similar to fatal levels in synthetic pyrethroids. Nevertheless, pyrethrum should be handled with the same caution as synthetic insecticides: safety equipment should be worn, and mixing with other chemicals should be avoided. People can be exposed to pyrethrum as a mixture of cinerin , jasmolin , and pyrethrin in the workplace by breathing it in, getting it in

368-511: The blades sometimes borne on petioles . They are usually deeply lobed and may have toothed edges. Most species have flowers in loose or dense inflorescences . The flower has layers of distinct phyllaries around its base and may be flat to hemispheric in shape. The flower has many yellow disc florets, sometimes over 300. Some species have ray florets in shades of yellow, or white with yellowish bases. Some species lack true ray florets but have flat yellowish disc florets that look like rays. The fruit

391-426: The eyes or on the skin, or swallowing it. The Occupational Safety and Health Administration (OSHA) has set the legal limit ( Permissible exposure limit ) for pyrethrum exposure in the workplace as 5 mg/m over an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) has set a Recommended exposure limit (REL) of 5 mg/m over an 8-hour workday. At levels of 5000 mg/m, pyrethrum

414-536: 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

437-652: The form of snow. Areas inside the Arctic Circle (66°34′ latitude) experience some days in summer when the Sun never sets, and some days during the winter when it never rises. The duration of these phases varies from one day for locations right on the Arctic Circle to several months near the Pole, which is the middle of the Northern Hemisphere. Between the Arctic Circle and the Tropic of Cancer (23°26′ latitude) lies

460-539: The safest insecticides for use around food. In 1998 Kenya was producing 90% (over 6,000 tonnes) of the world's pyrethrum, called py for short. Production in Tanzania and Ecuador is also significant. Currently the world's major producer is Tasmania, Australia. Pyrethrum has been used for centuries as an insecticide , and as a lice remedy in the Middle East ( Persian powder , also known as "Persian pellitory"). It

483-500: The weather patterns that affect many factors within the north coast. For the same reason, flows of air down toward the northern surface of the Earth tend to spread across the surface in a clockwise pattern. Thus, clockwise air circulation is characteristic of high pressure weather cells in the Northern Hemisphere. Conversely, air rising from the northern surface of the Earth (creating a region of low pressure) tends to draw air toward it in

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506-489: The winter months. In the Northern Hemisphere, objects moving across or above the surface of the Earth tend to turn to the right because of the Coriolis effect . As a result, large-scale horizontal flows of air or water tend to form clockwise-turning gyres . These are best seen in ocean circulation patterns in the North Atlantic and North Pacific oceans. Within the Northern Hemisphere, oceanic currents can change

529-481: Was sold worldwide under the brand Zacherlin by Austrian industrialist J. Zacherl . It is one of the most commonly used non-synthetic insecticides allowed in certified organic agriculture. The flowers should be dried and then crushed and mixed with water. A pheromone produced by these plants attracts ladybug beetles, and at the same time acts as an alarm signal to aphids. Rat and rabbit LD 50 levels for pyrethrum are high, with doses in some cases of about 1% of

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