EN
The type and distribution (locations) of calcium oxalate crystals in mature leaves of 19 taxa of Philodendron (subgenera Meconostigma, Pteromischum and Philodendron) were studied. The calcium oxalate crystals were mainly found in the form of raphides, druses, styloids and prisms. The leaves of Philodendron demonstrate the presence of five distinctive raphide crystal types (biforine, thin-walled spindle-shaped, wide cells containing a wide raphide bundle, bundles of obliquely overlapping crystal and unmodified cells with either a single crystal needle or their cluster). Styloids and druses were found in all taxa at varying frequencies. Simple prisms and variations in crystal forms were most frequently observed in the ground tissue in petioles and midribs. This study represents additional data concerning calcium oxalate crystals in Philodendron.