Nutlet morphology in the tribe Elsholtzieae (Lamiaceae)

A comprehensive study on nutlet morphology on 46 taxa from the tribe Elsholtzieae was conducted using stereomicroscopy, light microscopy, and scanning electron microscopy. The objectives were to evaluate the nutlet characteristics in a systematics context and to provide additional evidence for taxon delimitation. The nutlet shape varied from elliptical, widely elliptical, spheroidal, and ovate to pyriform. The size ranged from 0.50 to 2.70 mm in length and 0.34 to 2.65 mm in width. The three types of trichomes included simple non-glandular trichomes (Collinsonia punctata), clavate non-glandular trichomes (Elsholtzia cephalantha), and peltate glandular trichomes (Mosla grosseserrata and M. chinensis). We also report the presence of mucilaginous reaction in nine species of the genus Elsholtzia in Elsholtzieae. Four types (undulate, papillae-like projection, thorn-like pattern, and reticulate) and three subtypes (reticulate, reticulate-cellular, and supra-reticulate) of nutlet surface patt...