Begonia rex
Begonia rex, the king begonia, fancy-leaf begonia, or painted-leaf begonia is a species of flowering plant in the family Begoniaceae. It's a rhizomatous begonia first brought to England from Assam, and documented in 1857.
It is native to the East Himalayas, found from South Bhutan to North Myanmar, and has been introduced to Bangladesh, Cuba, The Dominican Republic, and Haiti.
These plants are noted for their dark leaves with prominent silvery grey bands, and are usually grown for their foliage, not flowers. When this species was introduced into cultivation, it became popular as a houseplant. Hybrids began to appear with varying leaf patterns as Rex begonias hybridize quite freely.
Rex Cultorum
The "original" Rex, Begonia rex ‘Putzey,’ was thought to be a distinct species until molecular taxonomy revealed that Begonia rex ‘Putzey’ is likely only one cultivar within a large complex of closely related begonias with similar appearances, all of which make up the species. The species and it's progeny are collectively referred to as the Begonia Rex Cultorum.Begonia rex ‘Putzey’ is in the parentage of over 500 cultivars in the Begonia Rex Cultorum Group of houseplants.
Other parents in the multitude of crosses made during the creation of the Group include Begonia annulata, B.cathayana, B.decora, B.diadema, B.dregei, B.grandis, B.hatacoa, B.palmata, and B.xanthina.