Comparative Study on the Vegetative and Floral Morphology of Three Ipomoea Species from Nigeria

Aim: The aim of this study was to determine the different vegetative and floral morphological features of three species of Ipomoea; Ipomoea aquatica, Ipomoea asarifolia and Ipomoea involucrate.

Area of Study, Collection and Identification of Plants: The study was conducted in Nnamdi Azikiwe University Awka, Anambra state of Nigeria. Three species were selected from the genus Ipomoea, they include: Ipomoea asarifolia, Ipomoea involucrate and Ipomoea aquatica. All the samples were collected from different locations across Nnamdi Azikiwe University premises.

Methodology and Statistical Analysis: The Morphological study was done by physical observation and measurement of physiognomic features of the fresh flower, leaf and stem. Plant type and growth habit were done by physical observation. The flower of each specimen was sectioned longitudinally and transversely to observe their placentation, stamen and carpel. The length of the sepal, petal, stamen and carpel were measured with a meter rule (cm). Counts were taken of the number of stamen, carpel, sepal, the inflorescence type, the floral symmetry, the number of sepal and petal colour were all observed and recorded carefully. The leaf texture, leaf arrangement, leaf shape, leaf type, leaf margin, leaf venation, leaf apex, leaf base were observed also and recorded. Data collected were analyzed using confidence interval at 95%, one way analysis of variance and mean separation by Duncan Multiple Range Test (DMRT) using SPSS version 21.

Results: Result of the vegetative morphology of three species of Ipomoea revealed that the three species are trailing herbs. The leaf shape is cordate for all species. The leaf apex of I. asarifolia is rounded while that of I. involucrata and I. aquatica is acuminate. The leaf base for I. asarifolia and I. involucrate is cordate while that of I. aquatic is truncate. The leaf arrangement and leaf venation is alternate and reticulate respectively for all species studied. The result on the quantitative vegetative characters revealed that the petiole is longer in I. asarifolia (13.655-16.045b) and shorter in I. involucrata (3.805-4.815 cm). The leaf length is also higher in I. asarifolia (9.522-10.898 cm) and lower in I. aquatic (4.273-4.887 cm). The leaf width is higher in I. asarifolia (11.799-12.301 cm) and lower in I. aquatic (4.351-5.29 cm). There was a significant difference in all quantitative vegetative characters studied (p<0.05). Result of the floral morphology of three species of Ipomoea revealed that the flower type is complete in the three species. There is presence of hairs on the sepals of I. involucrata but absent on I. asarifolia and I. aquatic. The floral symmetry is generally actinomorphic in all three species. Result on the quantitative floral characters revealed that diameter of flower is higher in I. aquatic (4.04-4.72 cm) and lower in I. involucrata (3.08-3.38 cm). There was a significant difference in the diameter of flower and pedicle length between the three species of Ipomoea.

Conclusion: Generally, the members of this genus Ipomoea have morphological differences or species uniqueness for easy identification.