Fig. 5. blr enhances a weak allele of stm. Twelve-day-old seedlings of stm-11 (A), blr stm-11 (B), stm-2 (C) and blr stm-2 (D). blr stm-11 double mutants are similar to stm-11 single mutants. No vegetative shoot is produced and the base of the cotyledons are fused. Plants homozygous for the weak stm-2 allele show limited fusion at the base of the cotyledons and initiate a vegetative shoot. The meristem defect is enhanced in blr stm-2 double mutants which do not develop vegetative shoot structures and there is significant fusion of the cotyledons.