S. stiriacum - in general

Photo of plant along with a small distribution map:

http://www.flora-austria.at/Endemiten-Detail/Taxa-Endemiten/Sempervivum-stiriacum.htm

stiriacum is a subspecies of S. montanum => S. montanum stiriacum

Thank you, Cromaphyto.

S. montanum subsp. stiriacum than, according to new taxonomy ...

Oooooooooooh, what a mess...

but since the distribution hardly overlaps, and there are NO reported hybrids, both taxa are clearly independent "evolutionary units". So under the more and more often used phylogenetic (evolutionary) species concept, they will probably be called different species as soon as a plant taxonomist seriously looks at them.

S. stiriacum is reported to have twice as many chromosomes as S. montanum.

Full species now, see post on S. carpathicum.

https://sempervivum.aforumfree.com/t2467-synonymes-for-s-carpathicum#7841

Of course anyone is free to accept or reject this change. To me, the reasoning is rather convincing.