^ Guillaume Chomicki; Luc P.R. Bidel; Feng Ming; Mario Coiro; Xuan Zhang; Yaofeng Wang; Yves Baissac; Christian Jay-Allemand & Susanne S. Renner (2015). "The velamen protects photosynthetic orchid roots against UV‐B damage, and a large dated phylogeny implies multiple gains and losses of this function during the Cenozoic". New Phytologist. 205 (3): 1330–1341. doi:10.1111/nph.13106.
The leaves of some orchids are considered ornamental. The leaves of the Macodes sanderiana, a semiterrestrial or rock-hugging ("lithophyte") orchid, show a sparkling silver and gold veining on a light green background. The cordate leaves of Psychopsis limminghei are light brownish-green with maroon-puce markings, created by flower pigments. The attractive mottle of the leaves of lady's slippers from tropical and subtropical Asia (Paphiopedilum), is caused by uneven distribution of chlorophyll. Also, Phalaenopsis schilleriana is a pastel pink orchid with leaves spotted dark green and light green. The jewel orchid (Ludisia discolor) is grown more for its colorful leaves than its white flowers.
^ Thomas J. Givnish, Daniel Spalink, Mercedes Ames, Stephanie P. Lyon, Steven J. Hunter, Alejandro Zuluaga, William J.D. Iles, Mark A. Clements, Mary T.K. Arroyo, James Leebens-Mack, Lorena Endara, Ricardo Kriebel, Kurt M. Neubig, W. Mark Whitten, Norris H. Williams, and Kenneth M. Cameron. 2015. "Orchid phylogenomics and multiple drivers of their extraordinary diversification". Proceedings of the Royal Society, series B (biological sciences) 282(1814):pages??. doi:10.1098/rspb.2015.1553.[full citation needed]
Orchids of all types have also often been sought by collectors of both species and hybrids. Many hundreds of societies and clubs worldwide have been established. These can be small, local clubs, or larger, national organisations such as the American Orchid Society. Both serve to encourage cultivation and collection of orchids, but some go further by concentrating on conservation or research.