Queen Sirikit is a cross between a cultivar of Mussaenda erythrophylla 'Dona Trining', a West African species and a cultivar of Mussaenda philippica ‘Aurorae’ which is native to the Philippines.
Queen Sirikit was bred in the Philippines in the 1940s. There are more than 200 known species of Mussaenda worldwide, of which about ten are found in cultivation, with three of these being widely used for landscaping.
(Smith, A. C. 1988. Flora Vitiensis Nova Vol. 4)
(McLaughlin, J. and Garofalo, J. Mussaendas for South Florida Landscapes)
(Staples, G. W. and D. R. Herbst. 2005. A Tropical Garden Flora: Plants cultivated in the Hawaiian Islands and other tropical places. Bishop Museum Press, Honolulu, Hawai`i.)