Climate appears sometimes to have some influence on the direction of branches, thus Dr. Falconer, as quoted by Darwin,[211] relates that in the hotter parts of India "the English Ribston-pippin apple, a Himalayan oak, a Prunus and a Pyrus all assume a fastigiate or pyramidal habit, and this fact is the more interesting as a Chinese tropical species of _Pyrus_ naturally has this habit of growth. Nevertheless many of the fastigiate varieties seen in gardens have originated in this country by variation of seeds or buds." M. Carriere has also recorded a curious circumstance with reference to the fastigiate variety of the false acacia _Robinia pseudacacia_; he states that if a cutting or a graft be taken from the upper portion of the tree, the fastigiate habit will be reproduced, and the branches will be furrowed and covered with short prickles; but if the plant be multiplied by detaching portions of the root-stock, then instead of getting a pyramidal tree with erect branches, a spreading bushy shrub is produced, with more or less horizontal, cylindrical branches, destitute of prickles.[212] =Eversion of the axis.=--In the case of the fig, the peculiar inflorescence is usually explained on the supposition that the termination of the axis becomes concave, during growth, bearing the true flowers in the hollow thus formed. The cavity in this case would probably be due not to any real process of excavation, but to a disproportionate growth of the outer as contrasted with the central parts of the fig. Some species of _Sempervivum_ have a similar mode of growth, so that ultimately a kind of tube is formed, lined by the leaves, the central and innermost being the youngest. The hip of the Rose may be explained in a similar manner by the greater proportionate growth of the outer as contrasted with the central portions of the apex of the flower-stalk. In cases of median prolification, already referred to, the process is reversed, the central portions then elongate into a shoot and no cavity is formed. A fig observed by Zuccarini (figs. 105, 106) appears to have been formed in a similar manner, the flower-bearing summit of the stalk not being contracted as usual, the flowers projected beyond the orifice of the fig. If this view be correct the case would be one rather of lengthening of the axis than of absolute eversion since it was never inverted. [Illustration: FIG. 105.--Fig showing prolonged inflorescence and projecting flowers.] [Illustration: FIG. 106.--Section of the same.] =Altered direction of leaves.=--The leaves partake more or less of the altered direction of the axis, as in fastigiate elms, but this is not universally the case, for though the stem is bent downwards the leaves may be placed in the opposite direction; thus in some specimens of _Galium Aparine_ growing on the side of a cliff from which there had been a fall of chalk, the stems, owing apparently to the landslip, were pendent, but the leaves were abruptly bent upwards.