Fig. 2

Cell morphologies of J. calliantha floral organs. a Jigsaw-shaped cells on the abaxial (lower) surface of the sepal. b Jigsaw-shaped cells on the adaxial (upper) sepal surface. c Slightly raised rounded cells of the adaxial petals. d Jigsaw-shaped cell of the abaxial petals. e Elongated cells of anthers. f Flattened and highly elongated cells of the stamen filaments. g Slightly raised rounded cells of the stamen base. h Slightly raised rounded cells of the corona. i Toothed elongated cells of the style. j Highly rounded cells of the ovary surface. k, l Sections through a mid-stage toluidine blue-stained flower bud showing mature conventional floral organs, prior to corona growth. m Initiation of corona development as a ring of tissue connecting the stamen bases. n, o Late-stage corona and petal development revealing similar inner layers of dark blue-stained rapidly dividing cells. p Section from the same flower as k, l toward the center of the flower showing the swollen stamen base stamen thecae. q Cartoon of a wax-embedded J. calliantha flower illustrating the angle of sectioning in n–p. Note that the fused corolla (light green) is artificially pushed upward to enclose the inner corona (red), stamens (purple), and gynoecium (yellow). pet petals, st stamens, gyn gynoecium, rec receptacle, cor corona, stb swollen stamen base. Scale bars = 100 µm for (a–j) and 1 mm for (k–p)