Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† pentăphyllon, i, n., = πεντάφυλλον, i. q. quinquefolium and pentapetes, five-leaved grass, cinque-foil, Plin. 25, 9, 62, § 109; App. Herb. 2.