S. ‘Constant Nymph’ is one of the classic hybrids, extremely vigorous and floriferous, quite unlike most of the other hybrids available prior to the 1950s. Its characteristic flower shape and floriferousness are a result of the crossing of a standard hybrid with S. johannis. Many other such crosses have been made, some producing more compact and brightly coloured cultivars.
I grew this specimen under lights in a cool basement, where it took up the better part of one bench. The leaftip to leaftip size was something like 30″, and at one point it had nearly 100 flowers open. Newer cultivars are usually considerably more compact, which is nice — but it is unfortunate that we seldom see the truly spectacular large-sized hybrids any more.