The organism grows quickly as a white colony on that pigments with age secondary to gray to brown conidia (1) Cleistothecia are produced which are 2-3 micrometers wide with thick walls and house asci with 8 acrospores. (1) Scedosporium apiospermum have similar appearing colonies, but differ from Pseudallescheria boydii by their singly produced conidia, bundled appearing hyphae, and lack of acrospores.