Umbilicus

I've never even heard of the genus, Trond - very interesting!

The latest issue of the Sedum Society journal has an excellent picture of a true Umbilicus: what you have is Rosularia, and I believe you have Rosularia rechingeri. It is closely allied to Rosularia chrysantha, which is generally much taller.

Both are natives of Turkey, a major center of distribution of the genus. Both Umbilicus and Rosularia are really just segregates of Sedum, sensu lato.

Recent Cladistic analysis of the Crassulaceae shows that most of what we called Sedum aren't any more no how: Rosularia and Umbilicus are both quite distant from the Sedum of the anglicum/acre group.

Umbilicus rupestris is widespread in Europe where it always grows on walls and suchlike vertical surfaces. It is very tricky to grow in the garden (in my experience)--although seeing it in nature it is abundant and seemingly adaptable. I have killed hundreds. It has peltate leaves with concave surfaces (technically termed peltate)--quite charming, and rather negligible chains of greenish flowers in midsummer.

I wrote a long account of Rosularia in cultivation for the Cactus and Succulent Society Journal of the USA a decade or two ago.

I know the name Umbilicus mostly from it being a synonym of the delightful shade succulent from the caucasus, Chiastophyllum oppositifolium (syn. Umbilicus oppositifolius), but my understanding neither name is valid any more.  A friend grows this, tucked into a shady wall, and the drooping chains of yellow flowers occuring now are most attractive.

Wikipedia says "Many of its species have been given synonyms under different genera such as Rosularia, Cotyledon, and Chiastophyllum" and that there were 90+ such names.  Most of the synonymy seemed to be with Rosularia species.  So, as Panayoti says, the whole concept of these related genera has been redefined... Panayoti, do you know of a good website the enumerates the genus-species revisions?  Also, is your Rosularia article available online anywhere?

"Rosularia chrysantha" pics:
http://davesgarden.com/guides/pf/showimage/244953/
http://www.franz-alpines.org/g_rosularia_chrysantha.html

Found a cultivar: Rosularia chrysantha "Pooh-Bear", never heard of it, but I want it!
http://www.flickr.com/photos/bric_uk/2875471823/

So Trond, given that your plant is probably Rosularia rechingeri (even if that name is outdated already), here are some photo links. I love these plants, and what I like about many of them, is that they can be ornamental in flower, which is more than I can say about most sempervivum, which they can resemble.  I shall miss the name Rosularia, it is such an onomatopoeic name.  Although, I'm not too sure how widely adopted the name changes are, one can still find Rosularia in many online floras:
http://www.vanherbaryum.yyu.edu.tr/flora/famgenustur/rosularia.htm

I notice that Wrightman's Alpines sells this one, check it out (good photo too):
http://www.wrightmanalpines.com/plant/rosularia-rechingeri-turkestanica
http://davesgarden.com/guides/pf/showimage/164985/
http://www.krischanphoto.com/gardens/rock/rosularia/rosularia%20rechinge...

Also found an interesting paper on a new variety of R. chrysanthum from 2009, I guess these are now classified in the genus Prometheum.  The paper is "Prometheum chrysanthum subsp. uludaghense (Crassulaceae), a new taxon from Turkey".
http://www.sekj.org/PDF/anb46-free/anb46-456.pdf

Thanks to both of you! That clear things up a bit.
Chiastophyllum I know. It is grown here.
Umbilicus rupestris have I seen often in Europe and tried to get hold of.
Anyway, whatever the name - it is a likeable plant.

Interesting, I did not realise the genus name had been used for things other than U rupestris... a thing I find quite fascinating, but doubt would be hardy.. still wouldn't mind trying sometime.... 
As for Chiastophyllum, I think Beavercreek was offering that...

Interesting, I hadn't heard of Umbilicus being used for other than Navelwort either. As a minor wild foraged edible, I've tried growing Umbilicus rupestris here, but it's not hardy enough.  It grows mostly in winter and very early spring, over its range, which doesn't include Norway,  flowering in March/April. I've seen it growing en masse most frequently (at least in the UK/France/Italy) in quite deep shade in dry woodland (i.e., not just walls). I nowadays grow it in a pot which I overwinter in the cellar (down to +3C)  where it grows as the temperature rises in spring. It then flowers here in June. I'm currently overwintering another species, U. horizontalis.

1-2. In my garden in June
3. October leaves in woodland, Brest, France
4. Late April flowering, Brest, France
5. Umbilicus and Parietaria in wall, Firenze, Italy

Trond: If I get seed in the autumn, I'll try to remember you...would be interesting to know if it will overwinter with you.

I see, by the way, that the Plant List notes Umbilicus chrysanthus as an accepted name.

Thanks for those pics, Stephen, interesting to see, esp the forest habitat.... I may try this sometime, overwintered indoors...(or maybe fulltime...)

Stephenb wrote:

Trond: If I get seed in the autumn, I'll try to remember you...would be interesting to know if it will overwinter with you.

I see, by the way, that the Plant List notes Umbilicus chrysanthus as an accepted name.

Thanks, Stephen! Appreciated. I recognize the plant from France and Portugal I think. I also remember seeing the plant growing in unexpectedly shady places.