Velamen radicum
Silvery-green shimmering Velamen radicum on the roots of a Cattleya
The velamen radicum ( Latin : velamen "cover, garment, veil"; radix "root") is a tissue made of dead cells that envelops the aerial roots of araces and orchids , especially epiphytic orchids. It has a sponge-like structure that can quickly absorb water and the nutrients it contains, store it and pass it on to the root cortex via an exodermis equipped with passage cells .
When dry, the Velamen radicum appears silvery-white due to its air-filled cells. When moist, the underlying tissues shimmer through, and the aerial roots of epiphytic organisms appear green due to chloroplasts embedded in the roots .
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- ↑ D. Denffer, H. Ziegler, F. Ehrendorfer, A. Bresinsky: Strasburger Textbook of Botany . 32nd edition. 1983, p. 124 .