Taxonimic Evaluation of some Species in the Family Cucurbitaceae
Ten species with four varieties in the family Cucurbitaceae were subjected to morphological, anatomical and palynological assessment with a view to finding additional diagnostic characters of taxonomic importance. The species studied were Telfairia occidentalis (Hook. f), Trichosanthes anguina Linn., Citrullus lanatus (Thunb.) Matsum. and Nakai., Cucumis melo Linn., Lagenaria siceraria (Molina) Stand., Cucumeropsis edulis (Hooker.f) cogn., Cucurbita maxima Duch.ex Lam., Cucumis sativus Linn., Luffa cylindrica M.(Roem) and Momordica charantia Linn. The habits of the species were noted while other qualitative morphological characters were studied by direct observation and quantitative morphological characters were measured. For anatomical studies, epidermal peels and venation study were carried out using standard methods. The palynological study was also carried out using standard methods. Quantitative data obtained were subjected to Analysis of Variance, Duncan Multiple Range Test and Palaentological Statistics (PAST). The result of the morphological study revealed many morphological similarities among the species with few variations. The Single Linkage Cluster Analysis using morphological quantitative data revealed the clustering of the taxa based on generic similarities with few overlaps. Characters delimiting species based on foliar anatomy include: epidermal cell shape and size on adaxial and abaxial surfaces, anticlinal wall pattern, stomata index and areole size. The plant species were all amphistomatic except in Telfairia occidentalis which was hypostomatic. Stomata type was largely brachyparacytic and anomocytic with anisocytic type occurring often. Staurocytic type of stomata was unique to Cucumeropsis edulis while contiguous stomata were unique to Cucumeropsis edulis and Telfairia occidentalis (Female). Glandular multicellular and nonglandular multicellular trichomes were encountered in all the species studied except in Trichosanthes anguina with only nonglandular trichomes. The palynological study revealed the following type of pollen grain shapes in the species studied: Spheroidal, Sub – Spheroidal, Sub – prolate, Sub – oblate, Prolate, Spheroidal to Oblate – Spheroidal, Prolate – Sphereoidal, Sub – Oblate, Oblate – Spheroidal. Acolpate, monocolpate, monoporate, bicolporate, tricolporate and tetracolporate pollen types were observed and documented. Tetracolpate pollen was encountered in Cucumeropsis edulis only. Classification based on size reveals that all the species studied belong to the Media group except Momordica charantia and Cucurbita maxima. Many morphological, anatomical and palynological characters separated the male and the female Telfairia occidentalis and the varieties of Lagenaria siceraria, Citrullus lanatus and Cucumis melo studied. The study provided additional information on the characters and relationships between the species and varieties in the family Cucurbitaceae, using taxonomic evidences derived from morphology, anatomy and palynology.