A phytochemical examination of various accessions of Phalaris coerulescens for the presence of toxic phenylethylamines, indoloamines and tetrahydro-beta-carbolines revealed the presence of oxindoles previously not reported to occur in Phalaris species. One of the oxindoles, the structure of which was elucidated by spectroscopic methods, has not hitherto been reported to occur naturally and has been given the;trivial name coerulescine. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.