Characterised by the rounded or scalloped, not toothed, segment margins. This is the correct name for most of the Christmas Cactus available. This is probably a hybrid raised in the 1840s by William Buckley at Rollisson's Nursery, Tooting, London, combining the graceful habit and pendent flowers of S. russelliana (Hook.) Britton & Rose with the free flowering and size of S. truncata.

Source: Thompson, A, ; Forbes, S.; Spencer, R. (1997). Cactaceae. In: Spencer, R.. Horticultural Flora of South-eastern Australia. Volume 2. Flowering plants. Dicotyledons. Part 1. The identification of garden and cultivated plants. University of New South Wales Press.