Fig. 4

Developmental anatomy of the HF. a the flower primordium initiated. b The calyx primordium initiated. c When the calyx covered the central zone of the flower, the petal primordium initiated. d, e The cetral zone of the flower becomes broad, then the stamen primordium intiated. f, g The central zone (cz) of the flower apex raised as a platform. h, i During stage 6, the sepals enclose the central zone of the flower bud and the carpel primordia begin to form, where the raised cells surround the floral apex as a ridge. j, k Gynoecium continues to grow upward to form a continuous hollow cylinder. l The central zone becomes broad, where the placenta primordia will be formed; m, n At stage 7, the medial stamens become stalked at their bases, the gynoecium grows as a hollow tube, and placenta primordia are observable. o Rapid growth of the placental primordia and style, and the unilocular formed. p Period of the formation of ovule primordium. q In the centre of the ridge, ovules will form. Bar = 100 μm. Cap, calyx primordium; pep, petal primordium; cz, central zone; sp., stamen primordium; rm., ring meristem; st, stamen; p, petal; pep, petal primordium; pl, placenta primordium