Book  (2012)  
 
p40. We know of one Riethmuller rose which was named but never released. 'Showboat' was a hybrid tea, "a bit like 'Ena Harkness' in flower, but with an even weaker neck." Roger Mann personal communication.
No horse called Showboat was racing in Sydney when Roger Mann saw the rose in the early Sixties, but the musical film Show Boat came out in 1951. Given the usual pattern, the rose was probably bred before 1951 and named in 1951.

p61 As we have seen, Roger Mann reports a red hybrid tea called 'Showboat' grown at Turramurra. This rose may be 'Denise McClelland' under another name.

p60. 'Showboat'. No date. Hybrid tea. Red. Extant - unknown.
p60. 'Denise McClelland'. 1964. Hybrid tea. Dark red. Extant - unknown.