Systematic Importance of Leaf Anatomical Characters in Some Species of <i>Microcos</i> Linn. Section <i>Eumicrocos</i> Burret. in Nigeria

Abstract

The leaf anatomy of six Microcos L. species belonging to section Eumicrocos in Nigeria was investigated by transverse sectioning of the lamina and examined by light microscope to determine their taxonomic significance in species delimitation and classification. The common anatomical characteristics in all the species are as follows: the uniseriate epidermis; the hypostomatic and bifacial leaves; presence of 2 layers of palisade tissues; presence of bundle sheath extension to both epidermises; presence of glandular and non-glandular trichomes; presence of secretory ducts on abaxial surface; presence of druse crystal in the mesophyll and midrib and; sclerenchyma cells associated with the phloem. Anatomical characters which are significant for species delimitation include: the presence/absence of sclerenchyma cells associated with the xylem in the midrib; presence/absence of starch grains in the mesophyll and midrib; the presence/absence of secretory ducts on the adaxial surface of the midrib; the presence/absence of medullary plates in midrib; the number of secretory ducts in the midrib and the midrib adaxial outline. The section can be separated into two distinct groups based on the number of spongy tissue layers in the mesophyll, number of sclerenchyma cells associated with the phloem and presence/absence of sclerenchyma cells in xylem both groupings correlated with those obtained from foliar epidermal and pollen characters. The importance of these characters is discussed in relation to the taxonomy of the taxon.