Page:The Botany of the Antarctic Voyage.djvu/351

Falklands, etc.] gulariter sinuato-dentatis subpinnatifidisve, margiiiibus reflexis, capitulis solitariis binis subcoryrnbosisve breviter pedicellatis late campanulatis, involucri squamis anguste lanceolatis disco paulo brevioribus.

Hab. Strait of Magalliaens, Port Gregory ; Capt. King.

Caulk lignosus, crassitie pennee passerina?, uncialis. Rami 3-4-pollicares, teretes. Folia pluriina, parva, - 1 unc. longa, undulato-crispata, vix2 lin. lata, inferne in petiolum angustata. Pedicelli j—l unc. longi, foliolis bracteolati. Capilula unc. longa, unc. diametro.

Port Gregory is described as surrounded by plaius, which are covered with a short grass, and possess nothing but a herbaceous vegetation. These features are so different from those of Port Famine, that should the Senecio Arnottii be identical with S. kmgipes, and the latter be transported to this locality, the appearance it would probably assume is that of 8. miser. That such may be the origin of the present plant is rendered still more likely, from an examination of Mr. Darwin's specimens of S. tricuspidatus, Hook., a discoid species, hitherto only gathered high up the river Santa Cruz in Patagonia. Mr. Darwin labels two very different looking individuals as belonging to this same species, the one large and leafy, with leaves broadly linear, dilated and deeply trifid at the apex, fully an inch or an inch and a quarter long, and the whole plant equally luxuriant with S. Arnottii, the other, again, has the squalid habit of S. miser, and foliage very simdar in size, shape and texture. Nor is it in habit and foliage alone that the Seneciones are liable to vary. The difference between some of the discoid and radiate species is almost confined to the presence or absence of a ray, and this is so remarkably the case, that I have found an analogue to almost all the discoid species described above, amongst the radiate, and MM. Hombron and Jacquinot figure a Magellanic species bearing both radiate and discoid flowers on the same specimen. Now since the S. Jacobaa of England, and other European species, vary in having or wanting the ligulate florets, so may these of Patagonia and Fuegia, and thus still further reduce the number of species.

It is worthy of observation that the discoid Seneciones are almost peculiar to the drier soil and climate of Eastern Patagonia and Fuegia, only one (S. candidans), an inhabitant of sandy places, being a Fuegian and Falkland Island species. I am not prepared to say how far this favours the supposition that the absence of a ray may be due to causes now in operation, but the same remark applies to a certain extent to the Seneciones of other countries, and to the geuus ChiUotrichum in Antarctic America.

There are several points connected with this genus of a much more interesting nature than the variation of its Protean species; such as the absence of characters in the species indicating natural groups; the scarcity of the species in Australia, which contains scarcely seventy, contrasted with their abundance in the Cape which possesses nearly two hundred ; then- absence in the Antarctic Islands south of New Zealand, and then' forming upwards of twice the largest genus of flowering plants in the flora of Fuegia and Patagonia. A still more singular fact is the confined range of the individual species, though belonging to one of the very largest genera that has an universal diffusion. Thus out of the twenty-one species to be enumerated in the present part, not one inhabits any other country but extra-tropical South America, except the introduced S. vulgaris. If the species are to be considered the offspring of variation, there must be allowed to Senecio what may be called a disposition to vary centrifugally, that causes the individuals to depart further and further from an original one in proportion as the genus spreads over the earth's surface. There is not with Senecio, as with the equally widely dispersed Gnaphalium, that tendency in the forms all countries present, to revert to a few typical species. The fact of the species of Senecio in each separate country being almost inextricable, may be cited in favour of variation as an agent producing what other naturalists suppose original creations. Against this hypothesis, however, it might be urged, that the S. vulgaris has shewn no tendency to vary during the eighty years which have, in all likelihood, elapsed since its first importation into the Falkland Islands.