A comparative study of the morphological and anatomical features of the leaves and stems of Stachytarphetajamaicensis and S. cayennensis was undertaken; both species have been widely reported in several herbal medicines. The presence of angular stem and pubescent leaves in the latter distinguishes it morphologically from the former, which is characterized by smooth circular stem and glabrous leaves. The use of a light microscope revealed the presence of trichomes in the leaf of S. caynnensis but absent in S. jamaicensis. Differences in epidermal structure and stomata arrangements were also prominent features for separating between these species.
Idu, M.; Erhabor, J. O.; and Odia, E. A.
"Morphological and Anatomical Studies of the Leaf and Stem of Some Medicinal Plants: Stachytarpheta jamaicensis (L.) Vahl. and S. cayennensis (L.C.Rich) Schau.,"
Ethnobotanical Leaflets: Vol. 2009
, Article 9.
Available at: http://opensiuc.lib.siu.edu/ebl/vol2009/iss11/9