Massonias and their allies
These bulbous plants are very impressive for opposite leaves as well as a brushy umbel of flowers. They form into very small genera of just several species though, the identification and classification are still confusing in horticultural scene.
Massonias are the most popular of all the allies. Especially Massonia pustulata has been already so popular among succulent growers in Japan that it may be considered a common species.
Both Massonias and Polyxenas are comparably easy to grow but we don't know whether Daubenyas are the same or not because we have little experience of them.