ve·la·men 
(və-lāmən)
(və-lāmən)n. pl. ve·lam·i·na (-lămə-nə)
1. Anatomy A membranous covering or partition; velum.
2. Botany A spongy layer of dead cells that covers the aerial roots of most orchids and certain other plants and may serve to absorb atmospheric moisture.
[Latin vēlāmen, covering, from vēlāre, to cover, from vēlum, a covering.]
vel′a·mentous (vĕl′ə-mĕntəs) adj.