Leaflet trichome micromorphology in the Dolentes-Brevipedes taxonomic complex (Mimosa L., Mimosoideae)

Abstract

We studied leaflets of 18 taxa of the genus Mimosa, specifically the Dolentes-Brevipedes taxonomic complex, focusing on micromorphology, type, shape, and density of trichomes. Within the nonglandular trichomes we described 3 types of nonbranched and 2 types of branched trichomes. We also described 2 types of stalked glandular trichomes, extending the recent classifications of trichomes in Mimosa. Multiseriate trichomes with lateral projections, which resemble incipient branching, are described here for many taxa. Most studied taxa have pubescent leaflets and show great variability in trichome density values. We also found 3 different types of blade margins with variation in type, alignment, and orientation of trichomes. Results show that the micromorphology of blade trichomes allows distinguishing groups of taxa in this complex, which could be a new tool for performing taxonomic treatment of both subseries.