Bryobium retusum, commonly known as Christmas Island urchin orchid,[2] is an epiphytic clump-forming orchid that has oval, fleshy green pseudobulbs, each with two leaves and between seven and twelve short-lived, self-pollinating, pale green, hairy flowers.

Bryobium retusum is an epiphytic herb that forms small dense clumps with crowded, cylindrical pseudobulbs 15–20 millimetres (0.59–0.79 in) long and 7–10 millimetres (0.28–0.39 in) wide.

[2][3] Christmas Island urchin orchid was first formally described in 1825 by Carl Ludwig Blume who gave it the name Dendrolirium retusum and published the description in Bijdragen tot de flora van Nederlandsch Indië.

[4][5] In 2005 Yan Peng Ng and Phillip Cribb changed the name to Bryobium retusum.

[6] The specific epithet (retusum) is a Latin word meaning "blunted", "rounded" or "notched at the apex".