Intracellular calcium oxalate crystal structure in Dracaena sanderiana

The chemistry, crystallography and ultrastructure of intracellular calcium oxalate deposits in the angiosperm, Dracaena sanderiana are reported here. Crystalline deposits extracted from mature leaves and leaf primordia of D. sanderiana were studied by scanning electron microscopy and X-ray powder di ffractometry techniques, and compared with X-ray standards for calcium mono hydrate and calcium oxalate dihydrate. Intracellular calcium oxalate deposits were of two types; calcium oxalate m onohydrate raphides or solitary calcium oxalate dihydrate crystals. Raphide -containing cells exhibited lamellate sheaths around the chamber walls, muc ilage-like materials surrounding the developing crystal chambers, and parac rystalline bodies with closely spaced subunits within the chambers. The int racellular calcium oxalate dihydrate crystals usually displayed typical tet ragonal-dipyramidal morphology, but development of some unusual crystal fac es occasionally occurred. Two intracellular hydrate forms of calcium oxalate (monohydrate and dihydra te) exist in D. sanderiana. The elaboration of crystal Yacuoles derived fro m rough endoplasmic reticulum and modified crystals with energetically unfa vourable faces suggest that precipitation of calcium oxalate dihydrate in D . sanderiana cells might be biologically controlled.