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...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.展开更多
Microcos Linn. (Malvaceae s.l) is a genus made up of about 60 spp. distributed in Asia and Tropical Africa. In West Africa, 8 species have been recorded of which six species have been documented for Nigeria to occur i...Microcos Linn. (Malvaceae s.l) is a genus made up of about 60 spp. distributed in Asia and Tropical Africa. In West Africa, 8 species have been recorded of which six species have been documented for Nigeria to occur in lowland rainforest. This study is designed to carry out preliminary foliar epidermal and pollen morphological studies with a view to advance the understanding of the taxonomic relationship between and among species in the genus using the Nigerian taxa. The foliar epidermal and pollen characters were investigated by light microscopy. The epidermises are composed of isodiametric, polygonal or irregular cells. Anticlinal walls are straight, curved or un-dulate. All taxa are hypostomatic with anisocytic, paracytic and staurocytic stomata types. The mean stomatal size varies from 13.8 × 13.5 μm in M. barombiensis to 16.0 × 18.0 μm in M. coriacea. The dense distribution of stellate trichomes on the abaxial surface of M. malacocarpa and the absence of crystals in M. oligoneura are diagnostic for these taxa. The pollen grains are small in size (10-25 μm), tricolporate with short colpi, subprolate or prolate. Mean colpi length varies from 15.7 μm in M. iodocarpa to 17.5 μm in M. malacocarpa. The ora size varies from 5.4 μm in M. barombiensis to 12.5 μm in M. malacocarpa. The ambient and ora size are significant in the delimitation of the studied taxa. The two groups obtained from epidermal and pollen characters correlate with those earlier obtained from morphological data.展开更多
文摘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.
文摘Microcos Linn. (Malvaceae s.l) is a genus made up of about 60 spp. distributed in Asia and Tropical Africa. In West Africa, 8 species have been recorded of which six species have been documented for Nigeria to occur in lowland rainforest. This study is designed to carry out preliminary foliar epidermal and pollen morphological studies with a view to advance the understanding of the taxonomic relationship between and among species in the genus using the Nigerian taxa. The foliar epidermal and pollen characters were investigated by light microscopy. The epidermises are composed of isodiametric, polygonal or irregular cells. Anticlinal walls are straight, curved or un-dulate. All taxa are hypostomatic with anisocytic, paracytic and staurocytic stomata types. The mean stomatal size varies from 13.8 × 13.5 μm in M. barombiensis to 16.0 × 18.0 μm in M. coriacea. The dense distribution of stellate trichomes on the abaxial surface of M. malacocarpa and the absence of crystals in M. oligoneura are diagnostic for these taxa. The pollen grains are small in size (10-25 μm), tricolporate with short colpi, subprolate or prolate. Mean colpi length varies from 15.7 μm in M. iodocarpa to 17.5 μm in M. malacocarpa. The ora size varies from 5.4 μm in M. barombiensis to 12.5 μm in M. malacocarpa. The ambient and ora size are significant in the delimitation of the studied taxa. The two groups obtained from epidermal and pollen characters correlate with those earlier obtained from morphological data.
