Preliminary results of the study of crystals in fruits of the clade Apieae of the family Umbelliferae

Abstract

The presence, shape and distribution of calcium oxalate crystals in fruits are of great importance for the taxonomy of Umbelliferae; these traits characterize tribes and subfamilies. We are talking about prismatic crystals, large druses and globular clusters 15-25 microns in size, which are clearly visible in a light microscope. Smaller crystals were practically ignored. We studied 20 species of the Apieae clade using conventional light and polarized microscopy, scanning electron microscopy, and energy-dispersive spectroscopy. Cross sections, the surface of the commissure and seed, exocarp and endocarp fragments were studied. Large differences between species are shown - from numerous crystals in the exocarp, mesocarp or endocarp, on the commissure to their complete absence in the pericarp. Crystals occur in the form of crystalline sand, small (up to 9 ^m) drusen, naviculas, prisms, and irregularly shaped inclusions. The calcium content in the pericarp is quite high, in different areas from 1 % to 13 %, a significant part of the calcium compounds do not have birefringence. Most of the crystals contain species of subclade B3. The significance of small crystals for taxonomy remains to be evaluated. The content of silicon in the studied fruits is low, < 0.3 %.