By its isolation, which leaves it freely exposed on every side to the influence of atmospheric agencies, and from the height which makes it the culminating point of France on this side of the frontiers of Alps or Pyrenees, the bare Provençal mountain, Mont Ventoux, lends itself remarkably to studies of plant species according to climate. At the base flourish the tender olive and that crowd of small semi-woody plants whose aromatic scent requires the sun of southern regions. On the summit, where snow lies at least half the year, the ground is covered with a northern flora, partly borrowed from the arctic regions. Half a day’s journey in a vertical line brings before one’s eyes a succession of the chief vegetable types met with in the same meridian in long travels from south to north. When you start your feet crush the perfumed thyme which forms a continuous carpet on the lower slopes; some hours later they tread the dusky cushions of Saxifraga oppositifolia, the first plant seen by a botanist who lands in July on the shores of Spitzbergen. In the hedges below you had gathered the scarlet blossoms of the pomegranate, which loves an African sky; up above you find a hairy little poppy sheltering its stalks under a covering of small stony fragments, and which opens its large yellow corolla in the icy solitudes of Greenland and the North Cape, just as it does on the highest slopes of Ventoux. Such contrasts have always a new charm, and twenty-five ascents have not yet brought me satiety. In August 1865 I undertook the twenty-third. We were eight persons—three who came to botanise, five attracted by a mountain expedition and the panorama of the heights. None of those who were not botanists have ever again desired to accompany me. In truth, the expedition is a rough one, and a sunrise does not atone for the fatigue endured. The best comparison for Mont Ventoux is that of a heap of stones broken up to mend the roads. Raise this heap steeply up to two kilometres, and give it a base in proportion, cast on the white of its limestone the blackness of forests, and you get a clear idea of the general look of the mountain. This heap of débris—sometimes little chips, sometimes huge masses of rock—rises from the plain without preliminary slopes or successive terraces to render ascent less trying by dividing it into stages. The climb begins at once, by rocky paths, the best of which is not as good as a road newly laid with stones, and rising ever rougher and rougher to the summit, a height of 1912 metres. Fresh lawns, glad rivulets, the ample shade of ancient trees—all that gives such a charm to other mountains is here unknown, replaced by an endless bed of calcareous rock broken into scales which yield under one’s feet with a sharp, almost metallic sound. For cascades Mont Ventoux has streams of stones, the sound of which, as they roll downward, replaces the murmur of falling water.