x engadinense Brügger, 1882
Parentage : Sedum annuum x S. alpestre
Type : Krättli, Brgg. 1881, collected in Upper Engadine, V. Bever, 1830 m.
Description (translation of the German protologue) :
Looking like a bigger, more robust and more elongated form of S. alpestre, however regarding form of leaves and petals resembling S. annuum, concerning colours, size and branching intermediate between the parents.
Stems creeping or procumbent-ascending, below branched, above simple, 6 – 8 cm high, leaves loosely arranged, sterile stems very few or none.
Leaves oblong-terete, 3 – 5 mm long, base distinctly spurred, spur obtuse whitish.
Cymes 3- to 7-flowered, rather lax, almost bifurcate.
Flowers pale yellow, 6 – 7 mm broad, petals oblong, acute, 3 x 1.2 mm.
Flowering time : July – August in 1800 – 1900 m, i.e. in areas where both parent species occasionally are co-occurring due to avalanches which dispatch plants of S. atratum from higher altitudes in regions where S. annuum is common. Otherwise S. alpestre is confined to alpine regions (2000 - 3000 m) while S. annuum is found growing in mountainous areas at the foothills of the Alps in the Engadin (below 2000 m asl.).
The introductory text to the descriptions of S. engadinense and S. erraticum calls these two taxa "transitional forms which very likely have to be considered hybrids" (Aufzählung neuer Pflanzenbastarde der Bündner- und Nachbarfloren (Enumeration of plant hybrids of Grisons and adjacent regions), compiled by Chr. G. Brügger (Jahresbericht der Naturforschenden Gesellschaft Graubünden's 25, 1882).
't Hart & Bleij (IHSP, p.237, 2003) consider both names as of unresolved application.