The study’s aim was to investigate the density and the distribution of calcium oxalate crystals in reproductive organ of “green” morph type of wild taro (Colocation esculent (L.) Schott). Reproductive organs of “green” wild taro included flowers, fruits, and seeds. Morphological features of wild taro were evaluated based on the physiognomic characteristics of fresh specimens. Reproductive organs of “green” type were sliced thin horizontally and vertically, and double-stained with carmine alum claque–iodine green dye. The results showed that three types of crystals (druse, rawhide bundle, and free needle-liked crystals) were detected at wild taro. Calcium oxalate crystals, depend on types, were endowed very frequently at spandex pith, female flower, male flower, fruit, and seed. Druses were located in parenchyma and collenchyma cells, and present in almost parts of reproductive organs except ovule, placenta, and seed. Druse crystals were founded dense on the top of synandrium. Rawhide bundles were observed in shape of box, before or biforine-liked cells, and often located in parenchyma or collenchyma area. Free needle-liked crystals were dispersed scatteredly or gathered in clusters. It presumed that three types of crystals in reproductive organs played an important role in self-protection against herbivorous animals or insects.