Pelargonium oblongatum (section Hoarea), a tuberous caudiciform from Namaqualand in South Africa's Northern Cape, in flower in late spring.
I've got a talk coming up this Saturday, at the Cactus and Succulent Society of Massachusetts, at Tower Hill Botanical Garden near Worcester. The meeting runs 1:00 to 4:00, and I'll probably start yakking at around 2:30.
My topic is going to be "Succulent Pelargonium." Pelargoniums are members of the geranium family, primarily native to South Africa. The usual garden center geraniums are hybrid Pelargonium, but the genus also includes probably 150+ species from arid habitats with succulent stems, succulent roots, or even somewhat succulent leaves. My talk will be a basic introduction to the group, covering a range of succulent species, with diversions into cultivation and propagation. I'll bring along some extra seedlings for people to try at home, too.
I'll be doing a similar talk for the Philadelphia Cactus and Succulent Society in November.