it seems that this months Succulent of the Month has caused quite a lot of interest. Eduart sent me a personal message regarding the taxonomy of the plant and I felt that like Buck's it should be available to all those who are interested in ensuring they have the correct name for a plant.
Very interesting and taxonomically speaking very difficult plants as there is a tremendous variation of forms. My knowledge is that C. undulata (sensu Jacobsen, or C. orbiculata var. undulata = C. undulata var. mucronata) is an earlier heterotype of Coptyledon orbiculata var. orbiculata, which makes sense to me as the name oblonga points to plants with longer leaves.
Haworth's C. undulata seems to be a quite different plant.
Here's a list of synonyms (probably most of them heterotypes):http://www.ville-ge.ch/cjb/bd/africa/de ... n&id=55450
including a distribution map.
also: Urs Eggli - Illustrated Handbook of Succulent Plants – vol. 4, Crassulaceae (2003) - very useful (but I can't remember now his coments on C. undulata if any).
I've also tried to have a decent view about this complex (rather than species in a traditional way I would say):http://www.cactusi.com/cactus.php?name= ... specie=282
but with focus on C. orbiculata var. orbiculata (and I have also missed few things by the time I wrote the text).
Although in Romanian you might find useful the list of synonyms and the list of names linked to other recognized varieties, plus some other names used by collectors and plant distributors, most of them not valid.
The number of forms, varieties, variants or regional types goes allegedly close to 100. Some of them it is said that once cultivated lose their characteristic feature so that the enormous range of habitat conditions may also play a role in the apparent huge variety of the plant. Even look-alike nursery stock plants end in few years as being total different to each other. Sometimes the plants are very reduced, not even 30 cm high, sometimes shrubby-like, with or without red leaf margins, more or less glaucous, with undulate margins or (mostly) not, deep green to silver grey, from big leaves to rather smallish - everything is possible.
One of the photos from my article (C. orbiculata var. orbiculata) is showing a quite different plant (smaller, with greenish-yellow leaves, different colour of the flowers) in a group of plants growing wild in New Zealand (it is naturalized here in coastal regions). Have no idea how it could be that different, just one plant out of few dozens forming this small population at Piha, on a high rocky outcrop isolated in the middle of the beach. The plants seem to vary quite a lot and regional "forms" (hybrids?) have been noticed even here. It's a taxonomic nightmare this plant!