The species usually seen, Chiastophyllum oppositifolium (quite a mouthful) is a lovely plant with fleshy, bright green leaves and producing stems with lots of small yellow flowers, each stem giving a graceful, curving appearance. With us it has performed best in rock crevices in a very wet area of the garden, but has also grown in dry, well drained places. It is also known as Umbilicus oppositifolius, and comes from the Caucasus.
Chiastophyllum (Umbilicus) oppositifolium has lovely, fleshy, scallop-edged leaves and arching stems of small yellow flowers.