Potential C-to-U RNA editing sites in the start codons (a) and stop codons (b) of the 19 lycophyte species. Sites were checked based on the chloroplast genome sequences. Blue bars (‘abnormal’) represent the percentages of genes with the start codon ACG and stop codon CAA, CAG, or CGA, which are potential RNA editing sites. Orange bars (‘normal’) represent the percentages of genes with the normal start codon ATG and stop codons TAA, TAG, and TGA. Gray bars (‘others’) indicate the percentages of genes with start or stop codons that do not fall into either category. † Complete plastomes sequenced, assembled, and annotated in this study.