Fig. 1

Phenotypes of nectar guide trichomes. (a) Front view of the whole corolla (upper) and enlarged view of the corolla throat of M. lewisii (Mlew, left), M. parishii (Mpar, middle), and their F1 hybrid (right). Scale bars, 5 mm (top row) and 1 mm (bottom row). The red circle marks the position where nectar guide trichome length were quantified. (b) Front view of F2 hybrids representing the four classes. Scale bars, 4 mm. (c) Light microscopy images of nectar guide trichomes of M. lewisii, M. parishii and F1 hybrids. Scale bars, 200 μm. (d) Quantification of nectar guide trichome length (n = 20 for each genotype). Error bars are 1 SD. Asterisks indicate differences from M. lewisii (** p < 0.01, student’s t test). (e) Frequency distribution of the four classes of F2 individuals