Intracellular calcium oxalate crystal structure in Dracaena sanderiana

Abstract

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 diffractometry techniques, and compared with X-ray standards for calcium monohydrate and calcium oxalate dihydrate. Intracellular calcium oxalate deposits were of two types; calcium oxalate monohydrate raphides or solitary calcium oxalate dihydrate crystals. Raphide-containing cells exhibited lamellate sheaths around the chamber walls, mucilage-like materials surrounding the developing crystal chambers, and paracrystalline bodies with closely spaced subunits within the chambers. The intracellular calcium oxalate dihydrate crystals usually displayed typical tetragonal-dipyramidal morphology, but development of some unusual crystal faces occasionally occurred. Two intracellular hydrate forms of calcium oxalate (monohydrate and dihydrate) exist in D. sanderiana. The elaboration of crystal vacuoles derived from rough endoplasmic reticulum and modified crystals with energetically unfavourable faces suggest that precipitation of calcium oxalate dihydrate in D. sanderiana cells might be biologically controlled.