The origin and chromosome numbers of cultivars of Kalanchoe blossfeldiana Von Poelln.: Their history and evolution

Summary Kalanchoe blossfeldiana was described by Von Poellnitz in 1935. It is an endemic species of Madagascar where it was discovered in 1924 by Perrier de la Bâthie, who described it as the variety coccinea of K. globulifera. By 1930 living plants had been spread throughout Europe and the United States. At the same time commercial growing was initiated by Blossfeld at Potsdam, Germany. Selection within the species and, from 1939, hybridisation with several other Kalanchoe species yielded cultivars from which many have disappeared. K. blossfeldiana, like two selections, has 2n=34 chromosomes. The remaining cultivars, which are likely of hybrid origin, are polyploids. They are usually tetraploids (2n=ca 68), but in some cases numbers of 2n=72, 75, 84, 85 and 96 have been counted. Polyploidy already occurred in 1939, when the first interspecific cross, in this case with K. flammea (2n=34), was recoreed. Other species which have been crossed with K. blossfeldiana are K. pumila (2n=40), K. grandiflora (2n=34), K. schumacheri (2n=?), K. kirkii (2n=?) and K. manginii (2n=34).