Taxonomic Significance of Morphological Characters in the Species of Stachytarpheta Found in Awka, Nigeria

Abstract

A morphological study on the genus of Stachytarpheta found in Awka, South Eastern region of Nigeria was carried out. This was done by physical observation and measurement of physiognomic features of fresh floral and vegetative parts of the plants. From the result of the analyses carried out, S. jamaicensis had an erect growth habit and stem branching was dichotomous, S. cayennensis was erect and low in growth habit, slightly woody at the base with dichotomous stem branching while S. angustifolia was weakly erect and stem branched dichotomously. Stem and petiole colour of S. jamaicensis and S. angustifolia was rarely similar while S. cayennensis had a purplish stem and petiole. Stem of the three species of Stachytarphetawere quadrangular (square shaped) towards the shoot but circular towards the base of the stem, Leaf was alternate or opposite and whorled in S. jamaicensis and S. angustifolia but opposite in S. cayennensis. Leaf colour was bluish or grayish in S. jamaicensis, greenish-gray in S. angustifolia and grayish-green flushed with purple in S. cayennensis. In addition, leaf shape, leaf base, leaf tip and leaf blade was also studied. Flowers were sessile in all three species of Stachytarpheta; they were semi immersed in the rachis depression in S. cayennensis. 3-5 flowers at a time in S. jamaicensis and S. angustifolia, 3-4 flowers in S. cayennensis. However, from the study carried out these morphological similarities are more between S. jamaicensis and S. angustifolia thereby delimiting S. cayennensis which had more isolated features.