Plastome Sequences Uncover the Korean Endemic Species Polygonatum grandicaule (Asparagaceae) as Part of the P. odoratum Complex

<b>Background/Objectives:</b><i>Polygonatum grandicaule</i> Y.S.Kim, B.U.Oh & C.G.Jang (Asparagaceae Juss.), a Korean endemic species, has been described based on its erect stem, tubular perianth shape, and pedicel length. However, its taxonomic status remains unclear due to limited molecular data. <b>Methods:</b> This study presents the complete plastid genomes (plastomes) of two <i>P. grandicaule</i> individuals and its close relative, <i>P</i>. <i>odoratum</i> (Mill.) Druce var. <i>thunbergii</i> (C.Morren & Decne.) H.Hara. <b>Results:</b> The plastomes, ranging from 154,578 to 154,579 base pairs (bp), are identical to those of <i>P</i>. <i>falcatum</i> A.Gray, <i>P</i>. <i>odoratum</i> var. <i>odoratum</i>, and another Korean endemic species, <i>P</i>. <i>infundiflorum</i> Y.S.Kim, B.U.Oh & C.G.Jang. All contain 78 plastid protein-coding genes (PCGs), 30 tRNA genes, and four rRNA genes, except for the pseudogene <i>inf</i>A. Phylogenetic analyses using 78 plastid PCGs and whole intergenic spacer (IGS) regions strongly support the three sections within <i>Polygonatum</i> Mill. and show that <i>P</i>. <i>odoratum</i> and its variety are nested within <i>P</i>. <i>falcatum</i>, <i>P</i>. <i>grandicaule</i>, and <i>P</i>. <i>infundiflorum</i>. <b>Conclusions:</b> Given the limited genomic variation and phylogenetic relationships, we propose treating <i>P</i>. <i>falcatum</i>, <i>P</i>. <i>grandicaule</i>, and <i>P</i>. <i>infundiflorum</i> as part of the <i>P</i>. <i>odoratum</i> complex, despite their morphological differences. This study offers valuable putative molecular markers for species identification and supports the application of plastome-based super-barcoding in the morphologically diverse genus <i>Polygonatum</i>.