COMPOSITA. 235 
[Emilia sonchifolia, DC., a widely dispersed plant in the tropics of the Old World, is 
believed to have been introduced into America, where, however, it is now pretty gene- 
rally diffused: ex. Orizaba, Mexico (Sailé).] 
197. SENECIO. 
Senecio, Linn. Gen. Plant. n. 953; Benth. et Hook. Gen. Plant. ii. p. 446. 
As here limited, this is the largest genus in the vegetable kingdom, numbering about 
900 species, having nearly the same range as the order, and presenting great variety in 
habit and duration. Several species and groups of species have been raised to the rank 
of distinct genera by various authors; but we have followed Bentham and Hooker, 
though a study of the species from all parts of the world might lead to some useful 
division. Perhaps the genus Cacalia might be retained for some of the species ; 
yet it is not easy to define it for the Mexican species alone. JS. cervariefolius and some 
of the allied species have a somewhat rigid pappus, though in other respects they do 
not differ from several others referred by De Candolle and other botanists to 
Cacalia. 
1. Senecio acerifolius, Hemsley, n. sp. 
Prorsus glaberrimus, foliis caulinis longiuscule petiolatis tenuibus seepissime acute 5-lobatis con- 
spicue venosis, capitulis corymbosis radiatis mediocribus, involucri bracteis ad 12 basi incras- 
satis, floribus radii paucis, ligulis longe tubulosis, acheniis glabris sulcatis. 
Herba? omnino glaberrima, ramis vel caulibus crassiusculis, teretibus, striatulis, nitidis, stramineis, 
internodiis quam folia brevioribus. Folia (caulina tantum visa) petiolata, tenuia, subrotundata, 
ad 5 poll. longa, sepissime 5-lobata, simul obscure remoteque calloso-denticulata vel integra, 
palmato-nervosa, conspicue reticulato-venosa, subtus pallidiora, basi leviter cordata, lobis diva- 
ricatis, vix acutis, terminali majore; petiolus gracilis, 9-18 lineas longus. Capitula corymbosa, 
radiata, 6-9 lineas longa, 30-40-flora, breviter pedunculata; corymbi axillares et terminales, 
5-10-cephali, longiuscule pedunculati; pedunculi partiales 6-12 lineas longi, bracteis linearibus 
instructi; involucri bractez ad 12, coriaceo-scarios, basi incrassate, late oblonge, acutiuscule, 
striate vel fere costate; receptaculum planum, foveolatum, nudum; flores radii ad 5-7, 
steriles (?) ; ligule breves, elliptico-oblongz, longe graciliterque tubulose; disci corolle anguste 
infundibuliformes, breviter 5-lobate, lobis ovatis, vix acutis ; antherz basi brevissime mucro- 
nulate ; styli rami apice rotundati, puberuli. Achenia (matura non visa) angusta, glabra, 
sulcata ; pappi sete tenuissime, fere integree. 
Sout Mexico, Oaxaca ((hiesbreght). Hb. Kew. 
In many of its characters this agrees with S. acutangulus; but the ‘angular stem and 
eight-leaved involucre of the latter will not admit it. 
9. Senecio acutangulus, Hemsley. 
Cineraria acutangula, Bertol. Fl. Guat. p. 35. 
Guatema.a, Volcan de Agua (Velasquez). 
3. Senecio amplifolius, Hemsley. 
Cacalia amplifolia, DC. Prodr. vi. p. 828. 
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