In this study, we describe a property of Gramineae genes, and perhaps all monocot genes, that is not observed in eudicot genes. Along the direction of transcription, beginning at the junction of the 5'-UTR, and the coding region, there are gradients in GC content, codon usage, and amino-acid usage. The magnitudes of these gradients to hinder the annotation the rice genome and to confound the detection of gradients are large enough protein homologies across the monocot-eudicot divide.