American Journal of Plant Sciences, 2014, 5, 2389-2401 Published Online July 2014 in SciRes. http://www.scirp.org/journal/ajps http://dx.doi.org/10.4236/ajps.2014.515252 Ergastic Substances (Calcium Oxalate Crystals) in the Leaf of Combretum Loefl. (Combretaceae) Species in Nigeria Chimezie Ekeke, Ikechukwu O. Agbagwa Department of Plant Science and Biotechnology, Faculty of Biological Sciences, University of Port Harcourt, Port Harcourt, Nigeria Email:
[email protected] Received 12 May 2014; revised 16 June 2014; accepted 6 July 2014 Copyright © 2014 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ Abstract Leaves of twenty-two (22) species of Combretum in Nigeria were examined for occurrence and distribution of different types and sizes of ergastic substances (calcium oxalate crystals). Fresh and herbarium specimens were used for the study. These specimens were wax embedded, sec- tioned, mounted and micro-photographed using Leica WILD MPS 52 microscope camera on Leitz Diaplan microscope. Results revealed two types of calcium oxalate crystals—crystal sand and druses. Based on the observed differences in the size of the crystals, three groups of calcium oxa- late crystals are reported [large crystals: 180.0 - 360.0 µm (241 ± 44.57 µm), moderate crystals: 90.0 - 144.0 µm (117.0 ± 20.60 µm), and small crystals: 18.0 - 72.0 µm (50.21 ± 20.42 µm)]. Crystal sand was found only in Combretum sp. 1 but druses of varying sizes predominated amongst spe- cies of the genus.