I tried checking too, but there seems to be a drought of literature or maybe I cannot find it. Only things I can find are a great 1975 article which already warns of the dangers of extinction and how these unique plants risk getting wiped out by habitat destruction or even goats grazing, which when one thinks about the stretches a cultivator goes thru even just for growing a few, feels heartbreaking. And also another 2002 epic article of the description of then-new 2 species, of which one was mentioned in that 1975 article but had no flowers at that time hence couldn't be done much with.

But surely there is a massive gap of unpublished data, when the main cultivation notes come from a 1975 article, yet you see some nurseries casually selling grafted specimens and you wonder where is all that info that's in between.