Fig. 3. Scanning electron microscopy of wild type, ids1-mum1 and ids1-mum1;sid1-mum3. (A) Wild-type maize tassel, side view. (B) Wild-type tassel, top view, showing seven rows of SPM (arrowheads). (C) Wild-type ear floret with initiating floral organs. Carpels are growing over the ovule primordium. (D) Older ear floret showing growing silk composed of fused carpels. (E) Top view of ids1-Burr ear showing six SPM rows (arrowheads). (F) ids1-Burr spikelets with florets in the axils of extra lemma bracts. (G) Older ids1-Burr spikelet with initiating floral organs. Floral organs initiate in a pattern similar to wild type. (H-M) ids1-Burr;sid1-mum4 double mutant. (H) Tassel primordium with a single BM (arrowhead). (I) Top view of tassel showing four rows of SPM (arrowheads). (J) Indeterminate male spikelets with multiple bracts and no florets. (K) Young ear primordium with four rows of SPM (arrowheads). (L) Female spikelet terminating in an ovule primordium. (M) Older female spikelet with bract-to-silk transformations. SPM, spikelet pair meristem; SM, spikelet meristem; BM, branch meristem; S, stamen; OP, ovule primordium; Le, lemma bract; LF, lower floret; Si, silk; F, floret; C, carpel. Scale bars: 100 µm.