In a survey of the Leguminosae (167 species of 89 genera), calcium oxalate crystals were found in tapetal cells in all three subfamilies (84 species of 52 genera). Crystal form ranged from small scattered crystals to lens‐like to various large prismatic types, and included the first report of styloid crystals in the Caesalpinioideae. Over half of the caesalpinioid and papilionoid legumes examined had crystals. Crystals were not common in the Mimosoideae, however, but this may be because of the small sample. The distribution of species with various crystal types, and of species lacking crystals, did not reveal any patterns that conform to the presently defined taxa. Crystals in tapetal cells have previously been reported only in the Commelinaceae and Labiata