B. rajah is a rhizomatous species with distinctive foliage. It was discovered in Malaya in 1894 by Ridley.
The rhizome is slender and creeping. Leaves are ovate, base cordate with overlapping blade bases, and approximately 10 cm. at maturity. The color is a deep mahogany on both upper and reverse surfaces (new leaves are almost red) and indented with distinctive green veins. The leaf area between the veins is raised, giving a large bubbly effect. Blossoms are pale pink, and appear in summer.
Humidity: B. rajah is strictly a closed container plant.
Water: It enjoys high humidity but will not tolerate wet feet. Water only when necessary.
Feeding: B. rajah responds to regular full strength foliar feeding.
Light and temperature: This species will only look its best when grown in a cool position in low light levels. If receiving too much light or heat the leaves tend to lose their rich color and become olive green.
Propagation: Propagation is by leaf stem, or wedge cutting, or by seed. Margaret Chandler of Western Australia had great success with freshly harvested seed, but there was no germination of seeds eight weeks old. Maybe this seed has a short viability.