Begonia rex 'Red Bull' is an exceptional hybrid developed by Antoon Hoefnagels of The Netherlands. Its leaves display a brilliant metallic red color with a darker shading where they attach to the petiole. The edges of the leaves have a waviness to them and may occasionally appear slightly darker compared to the rest of the leaf. This particular hybrid has a compact growth pattern, resulting in a full and lush appearance. Similar to other rex hybrids, the colors within the leaves may vary depending on the season.

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Genus name was established in mid 18th century: modern Latin, named in honour of the French administrator and amateur botanist Michel Bégon (1638–1710) by the botanist Charles Plumier (1646–1704), who discovered the plant on the island of Santo Domingo.