Nutlet Morphometry in the Lamiaceae

The Nepetoideae and the Lamioideae are the largest subfamilies of the family Lamiaceae comprising more than half of the family’s species including mostly shrubs or herbs, many of which are applied as culinary and medicinal herbs. The results of previous analysis of twenty-one species in the subfamily Nepetoideae indicated a relationship of nutlet size and shape with the taxonomic position, with larger nutlets in the tribe Elsholtzieae, intermediate in the tribe Ocimeae, and smaller in the tribe Mentheae, except for Salvia species. This work focuses on 49 species, 34 in the Nepetoideae and 15 in the Lamioideae, and shows differences in nutlet size and shape between both subfamilies. The nutlets of the Lamioideae are larger and have higher aspect ratio and lower circularity, roundness, and solidity values. Elliptic Fourier Transform equations were obtained allowing the representation of average outlines for each of these species. Curvature analysis indicates higher absolute values of maximum and average curvature in the subfamily Lamioideae. Morphometric analysis including geometric measurements, curvature, and the coefficients of Fourier equations reveals differences between genera and species in both subfamilies of the Lamiaceae that can be of applied interest in the taxonomy of this family.