SENECIO. This genus of Composite, 

 represented in Britain by the well-known 

 Groundsel and Ragweed, is perhaps the 

 most extensive in point of species in the 

 vegetable kingdom. Nearly 900 different 

 kinds are known to botanists ; they are 

 spread over all parts of the globe, but are 

 found in greatest profusion in temperate 

 reeions. They are either annuals, peren- 

 nials, shrubs or undershrubs, with entire 

 pinnatifid or variously toothed or lobed 

 leaves placed alternately on the stem ; and 

 solitary panicled or corymbose flower- 

 heads, the florets of which are either all 

 tubular, or more commonly the central 

 I tubular and the marginal strap-shaped. 

 The prevailing colour is yellow— purple, 

 i dingy white, or blue being comparatively 

 j rare. The essential character of the genus 

 I is to have an involucre consisting of a 

 I sinele series of scales of equal length, 

 which are often surrounded at the base by 

 a number of narrow bracts to which the 

 name calycule is given. 



There are 596 species described in De- 

 can dolle's Prodromus. Of these, South 

 Africa claims 200 , Europe, North Africa, 

 : and Western Asia, 115 ; South America, 103, 

 North America and Mexico, 55 ; the East 

 ; Indies, 43 ; Australia and the Pacific Isles, 

 ; 35 . Mauritius and Madagascar, 28 ; Canary 

 Isles, 10; and China and Japan, 5. Since the 

 ; publication of the Prodromus more than 

 300 species have been made known from 

 different countries, but the proportion to 

 each is nearly the same. 



The Groundsel, 8. vulgaris, the Ragwort 

 or Ragweed, S. Jacdbma, and our other 

 native sorts afford a good idea of the ap- 

 pearance of the European species, the 

 most noteworthy of which is perhaps the 

 well-known S. Cineraria, better known in 

 gardens as Cineraria maritima, exten- 

 sively used for planting in flower-beds 

 for the sake of contrast with scarlet and 

 other colours, its beautiful foliage being 

 clothed with short white down. It is a 

 half-hardy perennial, propagated by cut- 

 tings layers or seeds, and is found wild 

 on the shores of the Mediterranean. South 

 Africa is the native country of S. elegans, a 

 pretty autumn-flowering annual, having 

 the habit of the common groundsel, but 

 with brilliant purple flower-heads. Many 

 fine varieties of this plant exist. 



The generic name Cinerariais restricted 

 to a few Cape plants which differ from 

 Senecio in the achenes of the ray-florets 

 being winged. The beautiful early spring- 

 flowering plants cultivated in greenhouses 

 as Cinerarias belong however to Senecio, 

 and have been obtained by horticulturists, 

 by intercrossing with each other a number 

 of the Canary Island species, such as S. 

 ■populifolius, 8. Tussilaginis, &c. The deep 

 blue colour of some of the garden varieties 

 of these plants is singular in the genus, 

 and not at all common in the family, 



As South Africa is the richest in species 

 in the Old World, so is the Andean region 

 in the New ; and the species are there 

 remarkable for their shrubby habit. M. 

 Weddell remarks that the proportion with- 



out strap-shaped florets to those with such, 

 is as three to one in the Andes, while in 

 most other countries the reverse is the 

 case. In his Flora of the alpine regions of 

 the Cordilleras, M. Weddell describes 120 

 species of this genus, and it is curious to 

 remark the large proportion of these which 

 have the leaves quite glossy or glutinous 

 on the upper surface and clothed with 

 warm wool underneath, as if the better to 

 protect them from the excessive cold, for 

 many grow quite close to the perpetual 

 snow-line. The name Tola is given by the 

 Bolivians to some of the gummy-leaved 

 species of this gejius, which they use as 

 firewood. The name of the genus is taken 

 from the Latin senex ' an old man,' in allu- 

 sion to the white pappus-hairs which crown 

 the achenes. [A. A. B.] 



SENECIONIDJE. One of the large tribes 

 into which the Composites of the suborder 

 Tubuliflorce have been divided, and charac- 

 terised chiefly by the form of the style. 

 The most typical genera of its principal 

 subdivisions are Helianthus, Tagetes, An- 

 themis, Artemisia, Gnaphalium, and Senecio. 



SENECON (Er.) Senecio vulgaris. — 

 EN ARBRE. Baccharis halimifolia. 



SENECTUS. Old age is the most formi- 

 dable of all diseases, and one which all the 

 contents of Medea's cauldron cannot arrest. 

 Every organised being has its appointed 

 limits, and whether its period of existence 

 be a day or a century, no earthly power can 

 prolongit. Exogenous trees, however, seem 

 at first sight to contradict this ; but we 

 must remember that the new growth of 

 each year, dependent on the evolution of 

 the buds, must be regarded in some mea- 

 sure separately from the M'hole, to which 

 it bears some such sort of relation as that 

 of seed to a plant. As, however, each new 

 layer is in close connection with those 

 which went before, and since these after a 

 time are subject to decay, after the lapse 

 of years the first-formed wood perishes, 

 the tree becomes hollow, and the sound 

 wood is ultimately more or less affected by 

 the decayed matter within. The effect is 

 in many instances so slow, that athousand 

 years or more may pass before the general 

 , health is so affected as to induce complete 

 | destruction. Even in trees, however, the 

 I constitution after a time begins to fail, the 

 j sap is not carried to the extremities, and 

 I in consequence they die— indicating most 

 j surely that the tree is past its prime, and 

 that the central wood, if not actually de- 

 cayed, no longer performs its functions. 



In annual or biennial plants life is oc- 

 casionally prolonged to the second or 

 third year if anything has prevented the 

 formation of seed ; and amongst crypto- 

 gams, which multiply by cell-division as 

 well as by spores, a portion of the original 

 cell may exist for a long time in the ab- 

 sence of fruit, but no sooner is this formed 

 than death ensues as a necessary conse- 

 quence. [M.J B.] 

 SENEGAL-ROOT, The diuretic and very 

 ' bitter root of Cocculus Balds. 



