Notes on Kalanchoe ×Houghtonii (Crassulaceae Subfam. Kalanchooideae), an Early Hybrid between Two Species of K. Subg. Bryophyllum

Abstract: Aspects of the biology and history of Kalanchoe ×houghtonii D.B.Ward, one of the earliest known hybrids artificially created between two species of Kalanchoe Adans. (Crassulaceae subfam. Kalanchooideae), are discussed. Both parent species, K. daigremontiana Raym.-Hamet & H.Perrier and K. tubiflora (Harv.) Raym.-Hamet, are included in K. subg. Bryophyllum (Salisb.) Koorders. This hybrid was created artificially more than once on different continents. An amplified description is provided for the somewhat variable K. ×houghtonii D.B.Ward ‘Garbí’ D.Guillot, E.Laguna, López-Pujol, L.Sáez & C.Puche, a form of this nothospecies that has become naturalised on the Iberian Peninsula and slightly beyond. A new locality where it has become established in continental Portugal is recorded. Other forms of K. ×houghtonii have similarly become established in several mild-climate parts of the world. The nothogenus name ×Bryokalanchoe Resende is a synonym of Kalanchoe.