Desert Botanical Garden - http://www.dbg.org/ The purpose of the Desert Botanical Garden is to exhibit, conserve, study and disseminate knowledge of arid-land plants of the world, with a particular emphasis on succulents and the native flora of the Southwestern United States.
Succulents in South Africa and Namibia - http://www.cactus-mall.com/puyl/index.html Peter van der Puyl's photos and descriptions of succulents in South Africa and Namibia.
New Mexico Rare Plants - http://nmrareplants.unm.edu/ Descriptions, images, and range of many species.
Eastern Mojave Vegetation - http://www.schweich.com Vegetation of Mojave National Preserve, San Bernardino County, California, and autoecology of Swertia albomarginata, Coleogyne ramosissima, and Salvia dorrii .