| Summary: | Chloroplast (cp) DNA genomes are traditional workhorses for studying the evolution of species and reconstructing phylogenetic relationships in plants. Species of the genus <i>Castanea</i> (chestnuts and chinquapins) are valued as a source of nuts and timber wherever they grow, and chestnut species hybrids are common. We compared the cp genomes of <i>C. mollissima, C. seguinii, C. henryi</i>, and <i>C. pumila</i>. These cp genomes ranged from 160,805 bp to 161,010 bp in length, comprising a pair of inverted repeat (IR) regions (25,685 to 25,701 bp) separated by a large single-copy (LSC) region (90,440 to 90,560 bp) and a small single-copy (SSC) region (18,970 to 19,049 bp). Each cp genome encoded the same 113 genes; 82–83 protein-coding genes, 30 transfer RNA genes, and four ribosomal RNA genes. There were 18 duplicated genes in the IRs. Comparative analysis of cp genomes revealed that <i>rpl22</i> was absent in all analyzed species, and the gene ycf1 has been pseudo-genized in all Chinese chestnuts except <i>C. pumlia</i>. We analyzed the repeats and nucleotide substitutions in these plastomes and detected several highly variable regions. The phylogenetic analyses based on plastomes confirmed the monophyly of <i>Castanea</i> species.
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