"The innermost layer of the periderm in some plants, composed of parenchymatous cells", Late 19th cent.; earliest use found in Alfred Bennett (1833–1902), botanist and publisher. From German Phelloderm, alteration of Phelloderma from ancient Greek ϕελλός cork + δέρμα skin.[phelloderm etymology, phelloderm origin, 英语词源]