During a checking of generic names of Malesian plants I asked the opinion of Mr. C.Jeffrey (Kew) about the status of the monotypic genus Guerreroia Merr., described from Luzon. In his opinion it deserves generic distinction. Fortunately Merrill’s description was accompanied by an excellent figure from which I had much earlier concluded that the species had already been described in Bidens, as B. tridentata Turcz., also from Luzon, which Merrill had erroneously reduced to Glossogyne tenuifolia Cass, in his Enumeration of Philippine Flowering Plants vol. 3 (1923)613.