This plant is native to the Canary Islands and has been described since 1812.
This plant is fairly easy to grow . It has a long 'dormant' period and will tolerate erratic watering. Last winter I had it in my studio under normal flourescent studio lighting, it began to grow and had more leaves on it than I had ever seen before. It had a few flowers in May after I took it back outside and it had lost most of its leaves. The plant has bloomed sparsely every year that I've had it. It is in a clay pot, in a soilless mix to which I've added traction grit and marble chips. The marble chips were added to stabilize the plant in the pot. The plant will get top heavy and pull itself out of a lighter soil mix.
Here is a closer look at the base of the plant. If you were wondering what traction grit is, you can see it here where I have used it for a top dressing. (I purchase it at a lumber yard in 80 lb. bags for about $5.00 US)
This is a variation of the above plant. It has been in the marketplace for awhile, it may have occurred in someone's collection or nursery, and then was propagated from there. If anyone knows the history of this plant, please send me e-mail. I don't think that it occurs in the wild, as I haven't seen a description of it anywhere in the literature.
The varigated form is also easy to grow and will tolerate indifferent handling. However, like fusca, I have never heard of anyone who has one, ever seeing it bloom.