Plant glandular trichomes are epidermal secretory structures producing various specialized metabolites. These metabolites are involved in plant adaptation to its environment and many of them have remarkable properties exploited by fragrance, flavor, and pharmaceutical industries. The identification of genes controlling glandular trichome development is of high interest to understand how plants produce specialized metabolites. Our knowledge about this developmental process is still limited, but genes controlling glandular trichome initiation and morphogenesis have recently been identified. In particular, R2R3-MYB and HD-ZIP IV transcription factors appear to play essential roles in glandular trichome initiation in Artemisia annua and tomato. In this review, we focus on the results obtained in these two species and we propose genetic regulation models integrating these data. Glandular trichomes are multicellular organs that cover the surface of more than 30% of all land plants. Glandular trichomes synthesize, store, and secrete diverse specialized metabolites.Recent studies have reported genes and protein complexes regulating glandular trichome development in Artemisia annua and tomato. We propose a genetic model to explain the glandular trichome initiation in each species.R2R3-MYB and HD-ZIP IV transcription factor families play essential roles in glandular trichome initiation.Glandular trichome density and size are important factors regulating metabolic content. Increasing glandular trichome density by genetic engineering successfully enhanced specialized metabolite content without any adverse effect on plant growth.