Century Dictionary and Cyclopedia
- n. A genus of composite plants, type of tribe Senecionideæ and subtribe Eusenecioneæ. It is characterized by terminal flower-heads with a broad or cylindrical involucre of one or two rows of narrow bracts, numerous regular and perfect disk-flowers with truncate and cylindrical recurved style-branches and nearly cylindrical five- to ten-ribbed achenes, smooth or but slightly downy, and little or not at all contracted at the summit, which bears a copious soft white pappus of slender simple bristles. Some species have flower-heads calyculate with a few bractlets below, and the majority bear spreading pistillate rays, which are, however, minute in some and in others absent. This has been esteemed the largest genus of flowering plants, containing (including Cacalia, with Durand, 1888) at least 960 clearly distinct species; it is yet uncertain whether or not it is surpassed by the leguminous genus Astragalus, under which 1,300 species have been described, but perhaps not over 900 of these are genuine. The species of Senecio are mostly herbs, of polymorphous habit, either smooth or woolly, and bear alternate or radical leaves which are entire, toothed, or dissected. Their flower-heads are either large or small, corymbed, panicled, or solitary, and are in the great majority of species yellow, especially the disk-flowers. The genus is of almost universal distribution, but the range of individual species is remarkably limited. They are most abundant in temperate climates; probably about two thirds of the species belong to the Old World, and of these half to South Africa and over a fourth to Europe and the Mediterranean region. About 66 species are found in the United States, including the 9 species of Cacalia (Tournefort, 1700), separated by many authors; the others are chiefly low or slender herbs with bright-yellow rays, most numerous in the central States. American species are much more abundant in the Andean region, where they assume a shrubby habit and in three fourths of the species develop no ray-flowers, the reverse of the proportion elsewhere. Many of the Andean species grow close to the snow-line, and have leaves quite glossy and glutinous above and clothed with warm wool beneath; some gummy-leaved species have been used for firewood by the Bolivians under the name tola. In St. Helena and New Zealand a number of species become small trees. (See
he-cabbagetreeand puka-puka.) (For the principal British and American species, see ragwort, liferoot, and jacobæa; for the original species, S. vulgaris, a weed sold for cage-birds in London under the names bird-seed and chickenweed, and also called sencionand simson, see groundsel.) Several species have been in repute as remedies for wounds, as S. Saracenicus (for which see Saracen's comfrey, under Saracen). S. paludosus is known as bird's-tongue, S. hieracifolius as hawkweed, and S. Lyallii, of New Zealand, as mountain-marigold. S. lobatus, a tall and rather showy species of the southern United States, is known as butterweed, from its fleshy leaves. S. Cineraria, a bushy yellow-flowered perennial of Mediterranean shores from Spain to Greece and Egypt, is the dusty-miller of gardens, valued for its numerous long and pinnately cleft leaves, remarkably whitened with close down; from it the native dusty-miller of the Atlantic coast, Artemisia Stelleriana, is distinguished by its short, roundish, less deeply cut leaves. S. mikanioides, Cape ivy, a tender climber with smooth and shining bright-green angled leaves, from the Cape of Good Hope, is a favorite in cultivation. Several species are cultivated for their flowers under the generic name Senecio, as the orange S. Japonicus, and the purple and yellow S. pulcher, which reach nearly or quite 3 inches in diameter. S. argenteus, the silvery senecio, a dwarf 2 inches high, is valued for edgings, and several others for rock-gardens. The most important species, perhaps, are those of the section Cineraria, cultivated under glass, some of which have deep-blue rays, a color elsewhere absent from this genus as from most other composite genera.
- n. [lowercase] A member of this genus.
GNU Webster's 1913
- n. (Bot.) A very large genus of composite plants including the groundsel and the golden ragwort.
- n. enormous and diverse cosmopolitan genus of trees and shrubs and vines and herbs including many weeds
“P.eudo-Arnica_, and another species of Senecio (_Senecio frigidus_); the _Oxytropis nigrescens_, close-tufted and rich in flowers, not stunted here as in Chukch Land; several species of P.dicularis in their fullest bloom (_P. sudetica, P. Langsdorfii, P. Oederi_ and”
“On the highest parts of mountains (aprox. 3300-4500 m), specially adapted perennial forbs of generas such as Senecio, Nassauvia, Chaetanthera, Draba, Barneoudia, Leucheria, and Moschopsis, withstand the extreme wind and cold of the denuded rocky terrain, or the moving scree slopes.”
“On another hand, genera such as Senecio that present so many closely related species in the area, probably had a relatively recent pulse of diversification associated to the climatic fluctuations of Quaternary times.”
“Each plant is named "Senecio" because of the grey woolly pappus of its seeds, which resemble the silvered hair of old age.”
“On one summit of Mount Kahuzi Hedythrsus thamnoideus and Disa erubescens grow; on its main summit, between 3,200 and 3,308 m, Erica spp. grow with Senecio kahuzicus, Helichrysum mildbraedii, Huperzia saururus and Deschampsia flexuosa. 48 species with 2 unknown and 24 endemic species are found in the park.”
“It has many names but I know it as Common Ragwort, Jacobaea vulgaris or Senecio jacobaea.”
“The genus Senecio is particularly diverse, with half of the two dozen species found nowhere else.”
“Glaciers and rock occur at the highest altitudes, below which is alpine moorland with giant Senecio, giant lobelia and bogs, followed by zones of giant heather, bamboo, montane forest, mid-altitude forest, lowland forest, woodland, and savanna.”
“Her research involved, successively, identification and syntheses of a number of metabolites of carcinogenic and related polycyclic aromatic hydrocarbons (PAHs); simulation in vitro of biological oxidations of PAHs; isolation of carcinogens from shale oil and coal tar; and, from the 1960s, studies on the carcinogenic action of certain pyrrolizidine (Senecio) alkaloids and their ability to induce chronic lesions and tumors in the liver, pancreas, etc., and of diazomethane and certain nitroso compounds.”
“At all altitudes Senecio favors the damper and more sheltered locations, and in the alpine bogs is associated with another conspicuous plant, growing up to 10 m tall, the endemic giant lobelia Lobelia deckenii.”
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