Page:The Botany of the Antarctic Voyage.djvu/138

116 are at one time quite latent and at another conformable to our ideas of the effects of temperature and local circumstances. It is not only in the inflorescence that this group is liable to vary, but one form passes into others by the modifications of many of its organs at once, and this to so great an extent as to render it extremely difficult to define any one species between the two extremely dissimilar forms of L, Selago and L. Phlegmasia. Want of space obliges me here to confine my attention to the phases under which L. varium occurs ; these are so remarkable and were so wholly unexpected, that if we agree to consider such plants to be the same species as only offer forms undistinguishable to our senses, it will follow that the most of these supposed species must merge into one, and that Lijeopodium Selago is perhaps the most variable plant in the world.

L. varium, in Lord Auckland's group and Campbell's Island, is one of the finest of the genus ; it grows nearly erect on the bare ground, to a height of 1-2 feet, branching upwards, copiously leafy, with large spreading leaves, bearing at the apices of the branches numerous pendulous or drooping tetragonous spikes 2— 1 inches long. The stems of this species are often nearly the thickness of a swan's quill with spreading leaves as broad as the middle finger; I have no where seen handsomer specimens of it than this island presents, and more constant ones, for it is confined to the woods, and does not ascend the hills, neither varying in the narrow belt it inhabits nor seeking other localities where it would be exposed to the influence of exciting causes. The case is very different in Tasmania, where it also grows very commonly in the subalpine woods, and from whence I have specimens of Lycopodia presenting all intermediate stages between this and L. Selago, the connecting links being similar to what have been considered different species in other parts of the globe. Form and habit alone have not induced me to unite such dissimilar plants, for I have in vain sought with the microscope for diagnostic characters. The smallest Tasinanian specimens have been published as L. Selago (Hook, and Grev. in Bot. Misc., vol. iii. p. 101), they are about five inches high, simple at the base, branching upwards, in all respects similar to the American and European plant; they are likewise copiously supplied with gemma;, giving a squarrose appearance, these were first observed on the North-west American specimens of L. Selago, but are now known to be common on this species even in Scotland, where a variety occurs with small very acuminated leaves, those of the gemmEe being sometimes much altered, broadly obovate-oblong, acute, and keeled on the back. In the next stage of the Tasinanian plant, the stem ascends from a curving prostrate base, is about 5-G inches long, the lower leaves are linear, acute or acuminate, patent or subsquar-rose, subserrulate towards their arjices, obscurely nerved in the middle, the upper leaves are generally appressed for nearly the whole length of the stem, lanceolate or ovato-lanceolate, acuminate, acute or subacute, obscurely nerved, the margins cartilaginous with obsolete serratures: this form is quite identical with others of L. Selago from Cumberland, as well as with many from North Em-ope, Asia, and America. The two first described states inhabit exposed places, the following (the third), which grows on rocky places on the margins of woods, has the stems a foot or more high, branching, much curved and ascending at the base, sparingly branched above ; the leaves, except towards their apices, are patent or subsquarrose, larger and more loosely placed than in the former, with the nerve more thickened, those at the summits of the branches are similar to the leaves of the second state but more distinctly serrated. L. Selago of Tasmania resembles L. -sul/erecfum, Lowe, of Madeira and other wanner parts of the northern hemisphere, in which the leaves are generally all squarrose, nearly entire or strongly ciliate at the margins; this is such a fonn as a species, in passing from a colder to a more genial temperature, might be supposed to assume. In the fourth stage of the Tasinanian plant the leaves become larger, more patent or subreflexed, coriaceous and shining, still they are more or less acute, and the capsxdes are wholly axillary, sometimes confined to the middle of the branch, at others to the upper portion, which looks rather different from the lower and indicates the transition to L. varium. This state is nearly allied to some Indian forms of the genus, as also to L. hicidulum, Mich., which varies in the serratures of its leaves and in other particulars approaches very near, if it does not absolutely merge into American forms of L. Selago. Nor is it to be distinguished from Ceylon and Tristan d'Acuuha specimens of L. insulare, Carm., which further passes into L. crassum, Hook, and Grev., and through it into some other South American species.

The remaining Tasinanian states of L. Selago may be considered as belonging to L. varium ; in the fifth of these