Hyphodontia sambuci, the elder whitewash, is a basidiomycete fungal pathogen on deadwood, especially elder.[1]
It is resupinate, forming a very thin structure which is white, pruinose (flour-like dusting) or chalky in appearance. It is inedible.[1] It also grows on dead but still hanging branches of Fraxinus, Berberis, Nothofagus, Ulmus, Populus, Hedera, Ribes, Symphoricarpos and rarely on conifers such as Cryptomeria.[2]
As stated, H. sambuci occurs in North Europe mostly on Sambucus nigra, but there is a much bigger spectrum of substrates in warmer regions in southern areas. The variability of micromorphology increases in the tropics, but the macromorphological characteristics however always stay the same: the basidiocarp with chalky white color and often growing as aerophyte on dead branches of trees and bushes, that are still attached to the tree. H. sambuci consists of a complex of species. Similar species with capitate cystidia; thin-walled hyphae and exactly the same chalky white fruit body are H. griselinae and H. fimbriata. They can be differentiated by their spores and morphology of their basidiocarp.[2]