Roitman, G. G. (Cátedra de Jardinería. Facultad de Agronomía, Universidad de Buenos Aires, Av. San Martín 4453. 1417. Buenos Aires, Argentina; roitman@mail.agro.uba.ar) & A. Castillo (Jardín Botánico de Ezeiza, Jujuy 1037, 1804, Ezeiza, Prov. de Buenos Aires, Argentina; ezeizabotgard@hotmail.com). A new species, Herbertia crosae (Iridaceae), from Uruguay. Brittonia 56: 361–364. 2004.—Herbertia crosae (Iridaceae) is described from the stony grasslands of northwestern Uruguay. The new species resembles Herbertia lahue but can be easily distinguished by the narrower leaves, slender habit, the smaller pale lilac flowers, the presence of yellow spots at the base of the tepals, the red, adpressed hairs along the filament column, the presence of filaments free at the apex, the channeled style arm, the recurved secondary divisions of the style arm, and the smaller fruits. A key to the species of the genus is provided in which five species are now recognized.