South-central China and eastern Tibet shelter more plant species than almost any place on Earth, including a beautiful Osbeckia crinita flower. Between 1924 and 1927, the American botanist and explorer Joseph Rock (1884-1962) trekked through the area and nabbed specimens of more than 20,000 plants and 1000 birds. This site from Harvard's Arnold Arboretum is a portal to the university's trove of documents and photos about Rock's expedition.
You can track Rock's progress on his hand-drawn maps, browse a selection of his letters, and read published papers by him and others describing the specimen haul. A search feature lets you summon hundreds of original black-and-white photos from the expedition that capture the area's spectacular gorges and vegetation. A linked site describes recent Arboretum expeditions to the plant-rich region, which is threatened by deforestation and erosion.