Kambadaga Falls is a staircase of four cascades on the Kokoulo River in the Fouta Djallon highlands of Guinea, dropping more than sixty metres — and the rarest things here are growing on its wet ledges. The steps you are looking at exist because the river has cut through a hard cap of quartzite-rich sandstone into much softer rock beneath. The hard layers wear away slowly, so the water drops over one ledge after another instead of in a single leap. The same layering leaves the broad tilted slabs above the drop, where you can sit at the lip with the gorge opening below you. The dark crusts on the wet rock beside you are plants. They belong to a family that lives only in fast, aerated water, gripping bare stone with root-like discs and holding on through the full force of the flood season.
In 2018 botanists from Kew and the Herbier National de Guinée refound two of them here that had been feared extinct worldwide, and described a third new to science, Saxicolella futa. Everything they found lies along about a kilometre of this river, which is the entire known world of some of those species. The same plants once grew at Kinkon Falls, fifteen kilometres upstream, until a hydroelectric dam went in there in the 1960s; the fast water went with it and they disappeared. A dam is now proposed on this stretch too. Meanwhile the falls are the district's bathing place. Once the river drops after the rains, a deep dark pool stands at the foot of the main cascade, and villagers swim out into it through the afternoon. Where the water fans across the flat steps it runs ankle-deep, and in the late dry season whole families stand in the sheet of the cascade and let it break over their shoulders. As the river falls back, the crusts on the ledges are left in the open air and flower within weeks, so by January the rock those families wade across is in bloom.