11Two distantly-related North American montane monkeyflower species, Mimulus lewisii and 12 Mimulus tilingii, possess glandular trichomes. In this study, we characterized the 13 morphological and histochemical features of these glandular trichomes. For each species, we 14 used traditional light microscopy and scanning electron microscopy (SEM) to examine 15 morphological characteristics, and determined the main components of the secretory products 16 using histochemical and thin layer chromatography (TLC) staining techniques. We identified 17 type VI glandular trichomes on leaf surfaces in both species of monkeyflowers. These 18 trichomes exhibited stalk-cell lengths and head-cell counts that varied across adaxial and 19 abaxial leaf surfaces, stems, and sepals. Both species contained secretory products within the 20 cuticle of the trichome head, which releases the subcuticular metabolites when ruptured. 21 Histochemical tests in both M. lewisii and M. tilingii confirmed that secretions contained 22 lipids and polysaccharides. TLC plate staining indicated the presence of UV active 23 compounds with polyalcohols, lipids, and amines. The common morphology and chemistry 24 of the glandular trichomes suggests an analogous response to similar environmental 25 conditions in these evolutionary distant montane monkeyflowers. 26 27

Two distantly-related North American montane monkeyflower species, Mimulus lewisii and Mimulus tilingii, possess glandular trichomes. In this study, we characterized the morphological and histochemical features of these glandular trichomes. For each species, we used traditional light microscopy and scanning electron microscopy (SEM) to examine morphological characteristics, and determined the main components of the secretory products using histochemical and thin layer chromatography (TLC) staining techniques. We identified type VI glandular trichomes on leaf surfaces in both species of monkeyflowers. These trichomes exhibited stalk-cell lengths and head-cell counts that varied across adaxial and abaxial leaf surfaces, stems, and sepals. Both species contained secretory products within the cuticle of the trichome head, which releases the subcuticular metabolites when ruptured.Histochemical tests in both M. lewisii and M. tilingii confirmed that secretions contained lipids and polysaccharides. TLC plate staining indicated the presence of UV active . CC-BY-NC-ND 4.