Periplasmic cuticular calcium oxalate crystal deposition in Dracaena sanderiana

The chemical nature and biological basis for crystal deposition in epiderma l sub-cuticular areas are reported here for the angiosperm Dracaena sanderi ana. Position, development and identification of crystals in adult leaves of D. sanderiana was carried out using X-ray diffraction, crystal morphology and scanning and transmission electron microscopy techniques. Numerous small (< 1-6 <mu>m) calcium oxalate monohydrate crystals were foun d between the primary epidermal cell wall and the cuticle. Their formation was highly specific and predictable with respect to location and relative t iming of development during leaf ontogeny. The crystals were perisplasmic a s, at formation, the nascent epidermal cell wall was external to the crysta ls. Cuticular crystallization of calcium oxalate monohydrate in D. sanderia na occurred in crystal chambers situated between the plasma membrane and th e primary cell wall. Crystal deposition did not occur in developing guard c ells. The spatial pattern of calcium oxalate monohydrate within the epidermal cel ls, orientation of the crystallographic axes and the existence of crystal c hambers outside the plasma membrane suggest biologically controlled crystal deposition in D. sanderiana.