Fig. 1. Structure of wild-type and rbe flowers. (A) A wild-type flower. (B,C) rbe-1 flowers. The arrowhead in B indicates the small petal, and black and white arrowheads in C indicate the spoon-shaped and filamentous petals, respectively. (D) An rbe-2 flower. Arrowheads indicate filamentous petals. Sepals have been removed in B-D. (E-I) Scanning electron micrographs of petals of wild type (E-G) and rbe-1 (H,I). (E) A stage 15 wild-type flower. (F,G) Epidermal cells on the upper (adaxial; F) and lower (abaxial; G) surfaces of a wild-type petal. (H) A rbe-1 filamentous petal. Note that it is formed at the normal position. The sepal on the right side has been removed. (I) A high magnification image of the filamentous petal in H. The epidermal cells are flattened and elliptical with irregular epicuticular ridges. (J) Diagram of a flower. Petals are numbered based on their position relative to the inflorescence meristem (IM). (K-N) Longitudinal sections of wild-type (K,M) and rbe-2 (L,N) flowers. (K) A wild-type stage 6 flower. Arrowheads indicate the petal primordia. (L) An rbe-2 stage 6 flower. Arrowhead indicates the position where petal primordia should form. (M) A wild-type stage 10 flower. Arrowheads indicate the elongated petals. (N) An rbe-2 stage 10 flower. Arrowheads indicate the positions where petal should form. se, sepal; p, petal; st, stamen; ca, carpel. Scale bars: E, 250 µm; F,G,I, 10 µm; H, 200 µm; K,L,M,N, 50 µm.