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Comparative Morphology of the Leaf Epidermis in Six Citrus Species and its Biosystematic Importance

Inyama CN, Osuoha VUN, Mbagwu FN and Duru CM

Studies on comparative morphology of the leaf epidermis in six Citrus species- C. sinensis, C. limon, C. aurantifolia, C. reticulata, C. paradisi and C. maxima were carried out to ascertain the systematic importance of epidermal features in classification of these taxa. The epidermal carpet shows no appendages or subsidiary cells. The six species studied are hypostomatic with anomocytic type of stomata. Contiguous, mega stomata and special sheath cells are present in some species and could be of taxonomic and ecological potential. There are contiguous stomata in C. sinensis, C. limon, C. aurantifolia and C. maxima while lacking in C. reticulata and C. paradisi. The mega stomata are present in C. sinensis and C. limon but lacking in other species. The sheath cells are present in C. sinensis, C. limon, C. paradisi and C. maxima in the upper epidermis, and in C. limon, C. aurantifolia and C. reticulata in the lower epidermis. In the leaf epidermal carpet architecture there is a consistent variation among the species of citrus studied each exhibiting its own character and some with remote characters ranging from rectangular, cuboidal, triangular, pentagonal, hexagonal, pyramidal and trapezial in the upper epidermis while in the lower epidermis C. reticulata, C. paradisi and C. maxima distinguished themselves from others. The biosystematic implications of these findings have been discussed in the light of current literature.