Morphometric study of the genus Senna Mill. in South-western Nigeria

Mike O. Soladoye¹, Monsurat A. Onakoya¹, Emmanuel C. Chukwuma¹, Mubo A. Sonibare^2*

¹Department of Plant Science and Applied Zoology, Olabisi Onabanjo University,

P. M. B. 2002, Ago-Iwoye, Ogun State, Nigeria.

²Department of Pharmacognosy, Faculty of Pharmacy, University of Ibadan, Ibadan, Oyo State, Nigeria.

*Corresponding author. E-mail: sonibaredeola@yahoo.com.

Accepted 15 January, 2010.

   Abstract

Thirteen quantitative characters of the leaves, fruits, seeds and flowers were used in the study of eight Senna Mill. species. The characters include leaflet length, leaflet width, leaflet length/width, Number of leaflets, lamina length, petiole length, pedicel length, petal length, fruit length, fruit width, fruit length/width, seed length and seed width. These characters were measured with the aid of a line ruler and subjected to principal component analysis (PCA) and cluster analysis. The results revealed that three out of the thirteen characters employed contributed significantly in differentiating each of the species from the other at 95% level of significance. The species have great similarities hence their grouping under the same genus. Results also showed that Senna hirsuta (Linn.) H. S. Irwin and Barneby and Senna sophera (L.) Roxb. are more closely related, Senna occidentalis (Linn.) Link, Senna siamea (Lam.) H. S. Irwin and Barneby and Senna spectabilis (DC.) Irwin and Barneby all share some resemblance while S. occidentalis is distantly related to S. sophera.

Key words: Morphometrics, morphology, Senna, leguminosae, caesalpinioideae, numerical taxonomy.