New Solomon’s Seal Species Hidden in Plain Sight in Southeastern China

A striking botanical discovery has emerged from the misty forests of southeastern China: a species of Solomon’s seal that has been hiding in plain sight, misidentified for years as one of the region’s most familiar medicinal plants. In a study published in the journal PhytoKeys, researchers formally describe Polygonatum kiangnanense, a new species of the genus Polygonatum in the family Asparagaceae, collected from wild populations across the provinces of Anhui, Hubei, and Zhejiang. The find is remarkable not because the plant is rare or elusive, but because it grew alongside a species so well known that few thought to look twice. Its formal recognition now reshapes the taxonomy of a genus central to Traditional Chinese Medicine and demonstrates how modern genomics can settle disputes that morphology alone cannot.

The genus Polygonatum, commonly known as Solomon’s seal, is the most species-rich genus within its tribe, Polygonateae, with a distribution spanning the northern temperate, northern subtropical, and frigid zones of the Northern Hemisphere. More than 80 species have been recognized worldwide, and over 40 of them are endemic to China, making the country a key hub for the genus’ distribution and genetic diversification. The greatest concentration of species diversity stretches from the Himalayas to northern East Asia. Within Traditional Chinese Medicine, the dried rhizomes of select Polygonatum species, marketed as Polygonati Odorati Rhizoma, serve a dual role as both medicine and food, valued for properties described as nourishing yin, moistening dryness, and promoting fluid production. More than 20 additional species are used medicinally in regional practices, underscoring the considerable economic and therapeutic weight carried by the genus.

Species delineation in Polygonatum has traditionally rested on morphological characteristics such as leaf arrangement, filament morphology, flower size, shape and color, and rhizome structure. But these traits can overlap deceptively among close relatives. With the advancement of molecular biological techniques, chloroplast genome sequencing has emerged as a powerful tool for taxonomic identification and phylogenetic analysis in the genus, providing robust evidence for resolving the boundaries of closely related species. The new study combines both approaches, pairing detailed comparative morphology with complete chloroplast genome sequencing and phylogenetic reconstruction to test whether a suspicious plant from southeastern China truly belongs to the widespread species Polygonatum odoratum, or stands apart as something new.

The trail began during field surveys of wild Polygonatum germplasm resources conducted in southeastern China, encompassing Anhui, Hubei, and Zhejiang provinces. The researchers collected plant specimens that were initially identified as P. odoratum because of their similar rhizome morphology. However, detailed observations revealed notable differences in aboveground traits: a plant height ranging from 40 to 62 centimeters, oblong leaf blades, and yellowish-green campanulate-cylindrical flowers with a distinctive constriction at the mid-section. To confirm the taxonomic status of this plant, the team conducted comprehensive comparative morphological studies, chloroplast genome sequencing, and phylogenetic analyses. The cumulative evidence demonstrated that the taxon represents a previously unrecognized species, now formally described as Polygonatum kiangnanense sp. nov.

Between 2022 and 2025, the putative new species was sampled from five wild populations across the three provinces during key developmental stages, including growth initiation, flowering, and fruiting. Five individuals were transplanted to the Botanical Garden of West Anhui University for long-term monitoring of morphological traits and phenological patterns. For comparison, P. odoratum individuals were collected from Tonghua in Jilin Province and cultivated under identical environmental conditions. Voucher specimens of all sampled individuals were deposited in the Herbarium of Anhui University of Traditional Chinese Medicine. Chloroplast DNA sequences of the new species were generated through sequencing, while sequences of other Polygonatum species, including P. odoratum and P. infundiflorum, along with outgroup taxa from the closely allied genus Heteropolygonatum, were retrieved from the NCBI database.

The genomic workflow followed established pipelines. Genomic DNA was extracted from silica-gel-dried leaves using a commercial plant kit, and whole-genome sequencing was carried out on the BGISEQ-500 platform. Raw sequencing reads were filtered with the software fastp, and the chloroplast genome was assembled with SPAdes version 3.10.0. Genome annotation was performed using GeSeq and BLASTx, and the plastid genome map was generated with OGDRAW. The complete chloroplast genome sequences of P. kiangnanense, carrying GenBank accession numbers PX404796 and PX404797, and a newly sequenced P. odoratum from Tonghua, accession PX404798, have been deposited in GenBank. Comparative analyses of the chloroplast genomes of P. kiangnanense, P. odoratum, P. falcatum, P. langyaense, and P. infundiflorum were performed using Geneious software.

The results reveal a genome with a story to tell. The complete chloroplast genome of P. kiangnanense ranges from 154,571 to 154,593 base pairs in length, exhibiting the typical quadripartite structure characteristic of most angiosperms, consisting of a large single-copy region, a small single-copy region, and two inverted repeat regions. The genome contains a total of 133 genes, including 87 protein-coding genes, 8 rRNA genes, and 38 tRNA genes, consistent with the gene content observed in other Polygonatum species. Comparative analysis indicates that the chloroplast genome of P. kiangnanense is shorter than that of P. odoratum, which measures 155,310 base pairs, with the differences localized primarily to the large and small single-copy regions. The GC content of the new species ranges from 37.7 to 37.8 percent, closely mirroring its congeners.

Phylogenetic analyses based on complete chloroplast genomes, using both Maximum Likelihood and Bayesian Inference methods, reveal that all individuals of P. kiangnanense form a well-supported monophyletic clade, with bootstrap support of 100 percent and a Bayesian posterior probability of 100 percent. The dataset comprised chloroplast genome sequences of two individuals of the new species, 48 Polygonatum species represented by 67 individuals retrieved from NCBI, and two outgroup species, Heteropolygonatum alternicirrhosum and Heteropolygonatum ogisui, which are frequently employed as reliable outgroups in Polygonatum systematics. Maximum Likelihood analysis was performed using FastTree version 2.1.10 under the GTR plus GAMMA substitution model, with node support evaluated through 1,000 site-likelihood re-samplings and the Shimodaira-Hasegawa test. Bayesian Inference was conducted using MrBayes v3.2.7 with the GTR+F+I+G4 model selected via ModelFinder, and Markov chain Monte Carlo sampling was run for 100,000 generations.

Perhaps the most intriguing finding concerns the true P. odoratum. Although numerous P. odoratum chloroplast genomes are available in GenBank, preliminary phylogenetic analysis indicated that these sequences are polyphyletic, meaning they do not all descend from a single common ancestor as currently labeled. Most sequences clustering with P. kiangnanense appear to be misidentified specimens from southern China, whereas genuine P. odoratum from Northeast China forms a well-supported monophyletic clade clearly separated from the new species. The researchers therefore newly sampled and sequenced P. odoratum from Tonghua in Jilin Province to ensure robust phylogenetic inference. Interestingly, P. kiangnanense did not cluster with P. odoratum at all, but instead showed a relatively greater phylogenetic distance from it, forming a sister relationship with the clade containing P. falcatum, P. langyaense, P. infundiflorum, and P. grandicaule with strong statistical support.

Morphologically, the new species bears its closest affinity to P. odoratum, yet can be clearly differentiated by a suite of distinct traits. It has a terete rhizome measuring 9 to 14 millimeters in thickness, an angled stem, oblong leaf blades measuring 8.0 to 13.0 by 3.5 to 5.0 centimeters, and racemose inflorescences typically bearing one to two, occasionally three, pendulous flowers, compared with three to seven or even up to fourteen in P. odoratum. The flowers are yellowish-green, campanulate-cylindrical, and constricted at the mid-section, with perianth lobes 6 to 8 millimeters in length, accounting for half of the total flower length, whereas P. odoratum has lobes of only about 3 millimeters. The filaments are adnate to the lower two-thirds of the perianth, measuring 12 to 14 millimeters, smooth, and without apical saccate protrusions. The berries are black, 6 to 8 millimeters in diameter, containing two to four seeds, compared with seven to nine in P. odoratum. These traits far exceed the natural morphological variation range of P. odoratum, supporting the recognition of the taxon as a previously undescribed species.

The new species differs from its other close relative, the Korean endemic P. infundiflorum, in having an angled rather than terete stem, oblong rather than lanceolate leaves, campanulate-cylindrical rather than funnel-shaped flowers, and a distribution in southeastern China rather than Korea. The specific epithet kiangnanense refers to the Jiangnan region, south of the Yangtze River, where the species was originally discovered and where most of its populations occur. The Chinese name is jiang nan yu zhu. The species flowers from March to April and fruits from April to October, growing mainly under deciduous broad-leaved forests and bamboo forests at elevations of 200 to 1,300 meters, with a notable concentration south of the Yangtze River and scattered distribution in the Dabie Mountains.

The discovery carries implications beyond taxonomy. The researchers carefully checked specimen records in the Chinese Virtual Herbarium and found that, in addition to the collected specimens from Anhui, Hubei, and Zhejiang, some specimens deposited in recent years and previously identified as P. odoratum actually represent P. kiangnanense. These specimens are documented from Anhui, Zhejiang, Hubei, and Hunan provinces, providing reliable evidence for predicting the potential distribution of the new species. Accordingly, P. kiangnanense is considered to be naturally distributed mainly within these four provinces of southeastern China, concentrated in the Yangtze River Basin. The finding suggests that herbarium collections, often treated as static records, can conceal unrecognized diversity waiting to be uncovered with modern tools.

For a genus so deeply woven into medicine, agriculture, and culture, the recognition of P. kiangnanense is more than an academic exercise. Accurate species boundaries underpin conservation planning, germplasm management, and the sustainable use of medicinal plants. If specimens of the new species have been routinely mislabeled as P. odoratum, then the ecological ranges, population sizes, and harvest pressures attributed to the familiar species may need recalibration. The study also adds a newly identified P. odoratum chloroplast genome from northeastern China to GenBank, helping to untangle the polyphyletic mess that has clouded the species’ genomic record. As chloroplast genome sequencing becomes routine, botanists may find that more of China’s Solomon’s seals, long assumed to be well catalogued, still hold surprises of their own.

Subject of Research: Polygonatum kiangnanense (Asparagaceae), a new species from southeastern China

Article Title: Polygonatum kiangnanense ( Asparagaceae ), a new species from southeastern China

Article References: Xu, T., Song, X.-W., Wang, W., Li, W.-T., Han, B.-X., & Yi, S.-Y. (2026). Polygonatum kiangnanense (Asparagaceae), a new species from southeastern China. PhytoKeys, 277, 227-240. https://doi.org/10.3897/phytokeys.277.198454

Image Credits: AI Generated

DOI: 10.3897/phytokeys.277.198454

Keywords: Polygonatum, kiangnanense, Asparagaceae, species, southeastern, China, scientific research