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We have found previously that the sequences important for recognition of pre‐mRNA introns in dicot plants differ from those in the introns of vertebrates and yeast. Neither a conserved branch point nor a polypyrimidine tract, found in yeast and vertebrate introns respectively, are required. Instead, AU‐rich sequences, a characteristic feature of dicot plant introns, are essential. Here we show that splicing in protoplasts of maize, a monocot, differs significantly from splicing in a dicot, Nicotiana plumbaginifolia. As in the case of dicots, a conserved branch point and a polypyrimidine tract are not required for intron processing in maize. However, unlike in dicots, AU‐rich sequences are not essential, although their presence facilitates splicing if the splice site sequences are not optimal. The lack of an absolute requirement for AU‐rich stretches in monocot introns in reflected in the occurrence of GC‐rich introns in monocots …