Nicola Terracciano described Xiphion collinum (Iridaceae) in 1872, based on specimens collected in Campania region, southwestern Italy. The taxon has been treated as a synonym of Iris graminea, of I. lorea, or of I. sintenisii. Critical evaluation of original material and literature confirms that X. collinum and I. lorea are the same taxon, here regarded as a synonym of I. sintenisii. This species can be chiefly distinguished from I. graminea by its rosette leaves firmer and narrower, stem terete, outer bract not longer than the inner one, claw of the outer perianth segments without distinct wings, and fruits with a slender beak and ribs in close pairs. Besides, a lectotype is designated for the name Xiphion collinum and the correct combination in Chamaeiris is provided.