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, sectioned, 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 oxalate 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 species of the genus. Crystals were distributed within the spongy mesophyll, palisade mesophyll, sub-epidermis adaxial, sub-epidermis abaxial and between the palisade and spongy mesophyll. The findings of this work provide information on the occurrence and distribution of the crystals in the leaf epidermis of these taxa in Nigeria. The formation, occurrence and distribution of the crystal type in the Combretum species constitute dependable taxonomic character especially when combined with other characters.
Highlights
Combretum Loefl. belongs to the tribe Combreteae, subfamily Combretoideae in the family Combretaceae [1]
Crystals were observed in the spongy mesophyll layer, palisade mesophyll layer, between the palisade and spongy mesophylls, between the palisade mesophyll and the adaxial epidermis or between the spongy and the abaxial epidermis as shown in Figure 1 and Figure 2
Distribution of Calcium Oxalate in the Leaf Lamina In C. mooreanum and C. paniculatum Table 2, the oxalate crystals were found in the spongy mesophyll, palisade mesophyll, sub-epidermis adaxial and sub-epidermis abaxial layers
Summary
Combretum Loefl. belongs to the tribe Combreteae, subfamily Combretoideae in the family Combretaceae [1]. It. How to cite this paper: Ekeke, C. and Agbagwa, I.O. (2014) Ergastic Substances (Calcium Oxalate Crystals) in the Leaf of Combretum Loefl. O. Agbagwa comprises two subgenera Combretum with eleven sections and Cacoucia [2]. Agbagwa comprises two subgenera Combretum with eleven sections and Cacoucia [2] This family is highly heterogeneous and occurs mainly in the tropics, warm temperate and sub-tropical zones of the world. The members of this family are trees or small trees, shrubs or deciduous climbers, sometimes scrambling shrubs with 4- to 5-winged fruits [3] [4]. Forty-nine (49) known species and 8 imperfectly known species have been reported in West Africa with 25 species occurring in Nigeria [4].
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