Calcium oxalate crystals in the stems of Vitis vulpina L

Calcium oxalate crystals are found throughout the stems of Vitis vulpina as determined by light and electron microscopy. Prismatic calcium oxalate monohydrate (COM) crystals are present in the epidermis, cortex, vascular tissue and pith. Druse COM crystals occur in the cortex, vascular tissue and pith. Druse crystals are the most prevalent morphologic crystal form in the stem, occurring in files of cells extending parallel to the long axis of the stem. Raphide and styloid COM crystals are present in the cortex, vascular tissue and pith. In addition to these four morphological forms, a new crystal form not previously described is present. These new crystals are elongate, raphide-like crystals, but unlike raphide crystals, they appear to be spatially distributed in a nest-like manner in the vacuole of the crystal idioblast, lacking the ordered, parallel arrangement normally seen with raphide crystals in a raphide idioblast.