Fig. 9. SEM of developing spikelets. (A) Normal spikelet pair. The more advanced upper floret develops on the adaxial side and the lower floret, which is partially covered by the outer glume, forms on the abaxial side. (B) ids1-mum1 spikelet pair. One of the spikelets is developing a third floret between the upper and the lower floret. The carpel ridge (arrow) of the extra floret (f*) has an orientation opposite to that of the upper floret and similar to that of the lower floret. (C) Spikelet pair from an ifa1-r ids1-mum1 ear. An indeterminate meristem arises between two florets (sm*). The floral meristems produce additional carpel ridges as seen in the single ifa1 mutant. (D) Longitudinal row of ifa1-r zag1-mum1 spikelets. Lateral organs form from the ovule primordium (arrowheads). uf, upper floret; lf, lower floret; og, outer glume; ig, inner glume; st, stamen; sm*, indeterminate meristem.
