3 urn:lsid:arphahub.com:pub:F7FCE910-8E78-573F-9C77-7788555F8AAD urn:lsid:zoobank.org:pub:66878968-5FA3-48E4-A0CA-743FBBB0315D PhytoKeys PK 1314-2011 1314-2003 Pensoft Publishers 10.3897/phytokeys.279.192928 192928 Research Article Crassulaceae Cenozoic China Sedum hengshanense (Crassulaceae), a new species from Hunan, central China Qiu Xiang-Dong https://orcid.org/0009-0007-2464-6921 1 2 3 Xia Jiang-Lin 4 Zhang Feng-Di https://orcid.org/0009-0004-8943-8419 1 3 Wang Guo-Ping 4 Tan Guo-Ping 4 Xiong Yu xiongyu19891104@163.com 5 Wang Sheng-Wei https://orcid.org/0000-0002-8785-5065 1 3 6 Wei Neng weineng@wbgcas.cn https://orcid.org/0000-0002-0313-3912 1 3 6 Wang Qing-Feng https://orcid.org/0000-0001-9143-8849 1 3 6 State Key Laboratory of Plant Diversity and Specialty Crops, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, Hubei 430074, China State Key Laboratory of Plant Diversity and Specialty Crops, Wuhan Botanical Garden, Chinese Academy of Sciences Wuhan China https://ror.org/02j0gyf89 School of Ecology and Environment, Tibet University, Lhasa 850032, Xizang, China School of Ecology and Environment, Tibet University Lhasa China https://ror.org/05petvd47 University of Chinese Academy of Sciences, Beijing 100049, China University of Chinese Academy of Sciences Beijing China https://ror.org/05qbk4x57 Nanyue Arboretum of Hunan Province, Nanyue 421900, Hunan, China Nanyue Arboretum of Hunan Province Nanyue China Matoushan National Nature Reserve, Zixi 335300, Jiangxi, China Matoushan National Nature Reserve Zixi China Sino-Africa Joint Research Center, Chinese Academy of Sciences, Wuhan, Hubei 430074, China Sino-Africa Joint Research Center, Chinese Academy of Sciences Wuhan China

Corresponding authors: Yu Xiong (xiongyu19891104@163.com); Neng Wei (weineng@wbgcas.cn)

Academic editor: Takuro Ito

 2026 23 09 2026 279 201 214 76B5963E-B50A-5050-9BA2-88AD65869A9D 25 03 2026 09 09 2026 Xiang-Dong Qiu, Jiang-Lin Xia, Feng-Di Zhang, Guo-Ping Wang, Guo-Ping Tan, Yu Xiong, Sheng-Wei Wang, Neng Wei, Qing-Feng Wang This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Sedum hengshanense, a new species of Crassulaceae from central China, is described and illustrated. Morphological evidence supports its placement in Sedum sect. Sedum. The new species is morphologically similar to S. spiralifolium, S. sarmentosum, S. lineare, S. polytrichoides and S. morrisonense, but differs by its alternate phyllotaxy, leaf apex not twisted when young, papillate leaf margin, longer basal leaf spurs (1.0–1.4 mm long) with an acuminate apex, petals with the apex mucronate at the tip and broadly spatulate to subtrapezoid, obtuse-apexed nectar scales. Phylogenetic analysis recovers S. hengshanense as sister to the clade comprising S. spiralifolium, S. sarmentosum and S. lineare. The species is assessed as Vulnerable (VU) according to the IUCN Red List Categories and Criteria.

 Hengshan Mountain phylogeny succulent plant taxonomy Citation

Qiu X-D, Xia J-L, Zhang F-D, Wang G-P, Tan G-P, Xiong Y, Wang S-W, Wei N, Wang Q-F (2026) Sedum hengshanense (Crassulaceae), a new species from Hunan, central China. PhytoKeys 279: 201–214. https://doi.org/10.3897/phytokeys.279.192928

 Introduction

Sedum L., a member of the subfamily Sempervivoideae, is the largest genus in Crassulaceae, comprising approximately 490 accepted species (POWO 2026). It is widely distributed across all continents, except Antarctica, with major centres of diversity in the Euro–Mediterranean Region, West–Central Asia, East Asia and North America (particularly the USA and Mexico) (Thiede and Eggli 2007; POWO 2026). Species of Sedum are succulent herbs typically adapted to arid and/or rocky habitats (Thiede and Eggli 2007). Some species have ornamental value, such as S. acre and S. lineare, whereas others are used in traditional medicine, including S. sarmentosum and S. praealtum (Ma et al. 2017; Boriollo et al. 2020). In addition, several species, such as S. plumbizincicola, have a strong capacity for heavy metal accumulation and show potential for applications in soil remediation (Wang et al. 2023).

China harbours a rich diversity of Sedum. Recent studies indicate that around 148 species occur in China, including 118 endemics (Dai et al. 2025; Huang et al. 2025; Yi et al. 2025; She et al. 2026). Of these, 27 species have been described as new to science over the past two decades. These recent discoveries indicate that the diversity of Sedum species in China remains underestimated and that further taxonomic exploration is needed. In April 2024, we conducted a field survey in Hengshan Mountain, Hunan Province, China, where a previously unknown perennial caespitose Sedum species was discovered in flower. This species was clearly distinct from other Sedum species encountered at the site, including S. grammophyllum, S. sarmentosum, S. emarginatum, S. bulbiferum and S. alfredii. Over the following two years, successive field investigations were carried out to further document its distribution and morphological variation. Specimens were collected and living plants were transplanted to Wuhan Botanical Garden and Nanyue Arboretum of Hunan Province for detailed morphological examination. Based on comparative morphological studies and molecular phylogenetic analyses, the species is formally described as a new species, Sedum hengshanense.

 Materials and methods Morphological study

We conducted field surveys over two years in Hengshan Mountain, Hunan Province, to investigate the morphological variation, geographic distribution and phenology of the species in its natural habitat. Based on these observations, we collected voucher specimens and samples for molecular analyses during the flowering and fruiting periods. Additionally, detailed anatomical observations and video recordings of the flowers were made. Living plants were also collected and cultivated at Nanyue Arboretum of Hunan Province and Wuhan Botanical Garden, Chinese Academy of Sciences, where the plants are currently thriving. Morphological characteristics were examined and photographed using a Zoom Stereo Microscope-TS-10W (PDV, China) and an EOS M5 Canon camera. The morphology of pollen and seed was analysed and photographed with a HITACHI TM3030 scanning electron microscope (SEM) (Hitachi, Ltd., Japan).

To evaluate whether the new species had previously been collected or overlooked, we examined Sedum specimens and specimen records available through the Chinese Virtual Herbarium (CVH), including specimens mainly deposited in PE, IBSC, KUN, NAS, WUK, LBG, SCFI and other herbaria in China. We also examined our own field collections deposited in HIB and PE. Morphological comparisons were made, based on field observations, cultivated plants, herbarium specimens and relevant taxonomic literature.

 Molecular study

The nuclear ribosomal internal transcribed spacer region (ITS) was used for the phylogenetic analyses because it has been widely employed in phylogenetic studies of Sedum (Lu and Wang 2023; Chai et al. 2024; Yi et al. 2025; She et al. 2026). A total of 81 ITS sequences representing accessions within Crassulaceae were used to reconstruct phylogenetic trees and infer the phylogenetic position of the new species. Amongst these, two sequences of this newly-discovered species, obtained from samples collected from two populations on Hengshan Mountain, were newly generated in this study, whereas the remaining 79 sequences were downloaded from the National Center for Biotechnology Information (NCBI; https://www.ncbi.nlm.nih.gov/). Of the 81 sequences included in the analysis, 79 represent taxa of Sedum, while Aeonium viscatum and Greenovia aizoon were selected as outgroups following Yi et al. (2025). Details of the materials, including their sources and GenBank accession numbers, are presented in Table 1.

Taxa included in this study with voucher information, GenBank accession numbers and references. Missing data are indicated with “–”.

Taxon Voucher Accession number Reference
S. actinocarpum Ito 1749 LC229265 Ito et al. (2017a)
S. alfredii IBK194564 FJ919949 Wang and Shu unpublished
S. alfredii IBK114924 FJ919951 Wang and Shu unpublished
S. arisanense Ito 1842 LC229273 Ito et al. (2017a)
S. arisanense Ito 1836 LC229272 Ito et al. (2017a)
S. baileyi LBG0064555 FJ919935 Wang and Shu unpublished
S. bergeri – AY352897 Ni et al. unpublished
S. boninense Ito 2371 LC229242 Ito et al. (2017a)
S. bulbiferum Ito 416 LC229234 Ito et al. (2017a)
S. bulbiferum 130514hs41 KM111166 Xie et al. (2014)
S. bulbiferum 130524qz09 KM111165 Xie et al. (2014)
S. brachyrinchum var. brachyrinchum Ito 1359 LC229274 Ito et al. (2017a)
S. danjoense Ito 3658 LC260127 Ito et al. (2017b)
S. emarginatum 130512hs27 KM111145 Xie et al. (2014)
S. emarginatum 130529hz03 KM111146 Xie et al. (2014)
S. emarginatum 130503jz21 KM111147 Xie et al. (2014)
S. emarginatum 24041001 PP981038 Dai et al. (2025)
S. emarginatum 24052201 PP981037 Dai et al. (2025)
S. emarginatum AYJT-Nanjing-0308-08 EU592006 –
S. erici-magnusii Ito 2077 LC229235 Ito et al. (2017a)
S. erythrospermum Tsutsumi 1504 AB906473 Ito et al. (2014b)
S. formosanum Ito1115 LC530813 Ito et al. (2020)
S. formosanum Ito2296 LC260124 Ito et al. (2017b)
S. hakonense Mayuzumi C00005 AB088625 Mayuzumi and Ohba (2004)
S. hangzhouense Ito 2604 LC260130 Ito et al. (2017b)
S. hengshanense 1 QS16 PZ161008 This study
S. hengshanense 2 QS112 PZ161009 This study
S. japonicum Kokubugata 16749 AB906475 Ito et al. (2014b)
S. japonicum var. oryzifolium Ito 2285 LC229239 Ito et al. (2017a)
S. japonicum var. pumilum Ito 2287 LC229240 Ito et al. (2017a)
S. japonicum var. senanense Ito 2200 LC229238 Ito et al. (2017a)
S. jinglanii Y. S. Huang 21040301 OP288035 Huang et al. (2023)
S. jinglanii DNPC 2873 OQ162326 Huang et al. (2023)
S. jiulungshanense Ito 76 LC229243 Ito et al. (2017a)
S. kiangnanense CMQ1030 LC229244 Ito et al. (2017a)
S. lineare Mayuzumi C00120 AB088623 Mayuzumi and Ohba (2004)
S. lineare TNS: Ito667 LC229245 Ito et al. (2017b)
S. lipingense ZRB1479 MN150061 Zhang et al. (2019)
S. lungtsuanense Ito 3563 LC260131 Ito et al. (2017b)
S. makinoi Kokubugata 16730 AB906476 Ito et al. (2014b)
S. mexicanum Ito 647 LC229247 Ito et al. (2017a)
S. microsepalum Ito 2771 LC229282 Ito et al. (2017a)
S. microsepalum Ito 1965 LC229281 Ito et al. (2017a)
S. morrisonense Ito 2765 LC229290 Ito et al. (2017a)
S. morrisonense Hornat S1 LM993281 Nikulin et al. (2016)
S. multicaule Miyamoto et al. TI9596136 AB088631 Mayuzumi and Ohba (2004)
S. nagasakianum Ito 2064 LC229249 Ito et al. (2017a)
S. nokoense Kokubugata 10426 AB906478 Ito et al. (2014b)
S. oligospermum Ito 74 LC229250 Ito et al. (2017a)
S. oreades Rao 090803-03 KF113733 Zhang et al. (2014)
S. spiralifolium 130425sc01 KM111158 Xie et al. (2014)
S. spiralifolium 130425sc02 KM111159 Xie et al. (2014)
S. spiralifolium 130423zy62 KM111163 Xie et al. (2014)
S. polytrichoides var. polytrichoides CMQ1057 LC229251 Ito et al. (2017a)
S. polytrichoides var. setouchiense Ito 2298 LC229253 Ito et al. (2017a)
S. rupifragum Ito2070 LC229254 Ito et al. (2017a)
S. sarmentosum 130529lq03 KM111155 Xie et al. (2014)
S. sarmentosum 130511hs22 KM111156 Xie et al. (2014)
S. sarmentosum 130531la22 KM111157 Xie et al. (2014)
S. satumense Ito 2295 LC229256 Ito et al. (2017a)
S. sekiteiense Ito 1456 LC229295 Ito et al. (2017a)
S. simingshanense – PP464049 She et al. (2025)
S. simingshanense – PP464048 She et al. (2025)
S. subtile Ito 624 AB930277 Ito et al. (2014a)
S. subtile Shimizu 1999 AB088622 Mayuzumi and Ohba (2004)
S. taiwanianum Ito 2770 LC229297 Ito et al. (2017a)
S. taiwanianum Ito 2770 LC229296 Ito et al. (2017a)
S. tetractinum Ito 3623 LC260135 Ito et al. (2017b)
S. tianmushanense Ito 355 LC229261 Ito et al. (2017a)
S. tosaense Kokubugata 16726 AB906483 Ito et al. (2014b)
S. triactina 9596091 AB088629 Mayuzumi and Ohba (2004)
S. tricarpum Ito 2269 LC229259 Ito et al. (2017a)
S. tricarpum – PP989617 –
S. trullipetalum Miyamoto et al. 9420132 AB088630 Mayuzumi and Ohba (2004)
S. truncatistigmum Ito 3254 LC229306 Ito et al. (2017a)
S. xunvense – PV101948 Chai et al. (2024)
S. xunvense – PV101947 Chai et al. (2024)
S. yabeanum Ito 396 AB906490 Ito et al. (2014b)
S. zentaro-tashiroi Ohba 1998 AB088619 Mayuzumi and Ohba (2004)
Aeonium viscatum Mort 1432 AY082154 Mort et al. (2002)
Greenovia aizoon Mort 1425 AY082112 Mort et al. (2002)

Fresh leaves from two individuals of S. hengshanense were dried in silica gel and total genomic DNA was extracted using a modified CTAB method (Doyle and Doyle 1987). DNA quality was checked by 1% agarose gel electrophoresis. The ITS region was amplified with ITS1 and ITS4 primers (White et al. 1990), which have been commonly used in phylogenetic studies of Sedum (Huang et al. 2023; Ito et al. 2023; Yi et al. 2025). PCR amplification was performed following Ito et al. (2023) with minor modifications: 94°C for 3 min; 35 cycles of 94°C for 30 s, 50°C for 30 s and 72°C for 90 s; and a final extension at 72°C for 7 min. PCR products were checked on 1% agarose gels, purified and sequenced in both directions using the same primers. Forward and reverse reads were assembled and checked manually in Geneious Prime v.2025.0.3.

All ITS sequences were aligned using MAFFT v.7 (Katoh and Standley 2013) with default parameters and poorly-aligned regions were removed with trimAl (Capella-Gutiérrez et al. 2009). Alignments were then visually inspected and manually adjusted, when necessary, in Geneious Prime v.2025.0.3 (Kearse et al. 2012). Maximum-Likelihood (ML) analysis was conducted using IQ-TREE v.2.2.0. The best-fitting nucleotide substitution model was selected using ModelFinder according to the Bayesian information criterion (BIC; Kalyaanamoorthy et al. 2017) and SYM+I+G4 was selected as the optimal model. Branch support was assessed using 5,020 ultrafast bootstrap replicates. Bayesian-Inference (BI) analysis was conducted using MrBayes v.3.2.6 (Ronquist et al. 2012) under the GTR+I+G model. Two independent runs, each with four Markov chains, were conducted for 2,000,000 generations, with trees sampled every 1,000 generations. The first 25% of sampled trees were discarded as burn-in. Convergence was assessed by confirming that the average standard deviation of split frequencies was below 0.01 and that effective sample sizes (ESS) for all parameters exceeded 200. The resulting phylogenetic trees were visualised and annotated using the Interactive Tree of Life (iTOL; Letunic and Bork 2007).

 Results Morphological comparisons

The carpels and follicles of Sedum hengshanense are adaxially gibbous. According to the sectional circumscription of Fu and Ohba (2001), the species is, therefore, placed in Sedum sect. Sedum. The species is readily recognised by its alternate and imbricate leaves, a long basal leaf spur, leaf margins with conspicuous papillae and broadly spatulate to subtrapezoid nectar scales with obtuse apices.

Morphologically, S. hengshanense is similar to S. spiralifolium, S. sarmentosum, S. lineare, S. polytrichoides and S. morrisonense. Sedum hengshanense shares with S. spiralifolium, S. sarmentosum and S. lineare a perennial habit, the presence of a basal leaf spur, petals and nectar scales of comparable size and papillate seed surfaces. However, the new species differs from these species in a combination of leaf arrangement, leaf texture, leaf shape and size, the length and apex shape of the basal leaf spur, the presence of conspicuous papillae along the leaf margins and papillate sepal apices (Table 2). Sedum hengshanense also resembles S. polytrichoides and S. morrisonense in having erect flowering stems, alternate leaves and young leaves not twisted at the apex. However, it differs from both species in having papillate leaf margins, papillate sepal apices and petals with the apex mucronate at the tip. In addition, S. hengshanense differs from S. polytrichoides in having oblong-lanceolate rather than linear to linear-lanceolate leaves and longer basal leaf spurs (1.0–1.4 mm vs. ca. 0.8 mm). It differs from S. morrisonense in having oblong-lanceolate, thinner and narrower leaves rather than oblanceolate to linear-spatulate, thicker and broader leaves and longer basal leaf spurs with acuminate rather than obtuse apices (Table 2).

Comparison of S. hengshanense and its morphologically similar species. Missing data are indicated with “–”.

Character S. hengshanense S. spiralifolium S. sarmentosum S. lineare S. polytrichoides S. morrisonense
Flowering stem Erect Erect Procumbent Erect Erect Erect
Phyllotaxy Alternate, imbricate 3-verticillate 3-verticillate 3(4)-verticillate Alternate Alternate, imbricate
Tender leaf Not twisted at apex Apex twisted Not twisted at apex Not twisted at apex Not twisted at apex Not twisted at apex
Leaf blade Oblong-lanceolate Linear-lanceolate Oblanceolate to oblong Linear Linear to linear-lanceolate Oblanceolate to linear-spatulate
Leaf margin Papillate Not papillate Not papillate Not papillate Not papillate Not papillate
Basal leaf spur 1.0–1.4 mm long, apex acuminate 1.0–1.6 mm long, mostly 3-lobed, middle tilted Ca. 1 mm long, apex obtuse Ca. 0.9–1.2 mm long, apex subacute Ca. 0.8 mm long, apex obtuse to truncate Ca. 0.5 mm long, apex obtuse
Leaf (length × width) 7–10 × 1.5–2.0 mm 10–25 × 2–3 mm 15–28 × 3–7 mm 10–15 × ca. 2 mm 5–11 × 1–2 mm 10–15 × 2.5–3 mm
Leaf thickness Ca. 0.6 mm Ca. 1 mm Ca. 1.5 mm Ca. 0.7 mm Ca. 0.7 mm Ca. 1 mm
Sepal Papillate at apex Not papillate at apex Not papillate at apex Not papillate at apex Not papillate at apex Not papillate at apex
Petal 5–6 × 1.2–1.5 mm, apex mucronate at the tip 4–7 × 1–2 mm, apex mucronate at the tip 5–8 × 1–2 mm, apex mucronate at the tip 4–6 × 1.0–1.5 mm, apex not mucronate at the tip 5–7 mm, apex not mucronate at the tip 4–6 × ca. 1.2 mm, apex not mucronate at the tip
Nectar scale Broadly spatulate to subtrapezoid, apex obtuse Nearly fan-shaped, apex obtuse Cuneate-quadrangular, apex subemarginate Broadly cuneate to subquadrangular, apex obtuse Broadly rounded-cuneate, base cuneate, apex broadly rounded Obovate
Nectar scale size Ca. 0.5 × 0.3 mm Ca. 0.5 × 0.2 mm Ca. 0.5 × 0.5 mm Ca. 0.5 × 0.5–0.6 mm Ca. 0.3 × 0.3 mm –
Flowering period Apr–May Apr May–Jul Apr–May Jul–Aug Jul–Aug
Molecular phylogenetic analyses

Based on the ITS dataset, we reconstructed both Maximum-Likelihood (ML) and Bayesian-Inference (BI) phylogenetic trees. The two analyses yielded largely congruent topologies and the branch support values (bootstrap support, BS) and posterior probabilities (PP) for each node are shown on the ML tree (Fig. 1). Sedum hengshanense forms a distinct lineage and is sister to the clade comprising S. spiralifolium, S. sarmentosum and S. lineare, with full support (BS = 100%, PP = 1). This molecular evidence further supports S. hengshanense as a distinct species.

10.3897/phytokeys.279.192928.figure1 96683326-1CA9-5AB7-A55D-E2980D71CC26

A. Maximum Likelihood phylogeny of Sedum hengshanense and its relatives inferred from ITS sequences, with the new species shown in bold red; B. The same tree as A showing branch lengths proportional to nucleotide substitutions per site.

https://binary.pensoft.net/fig/1788070 Discussion

The recognition of Sedum hengshanense as a distinct species is supported by both morphological and molecular phylogenetic evidence. Although the species is morphologically similar to several related species, including S. spiralifolium, S. sarmentosum, S. lineare, S. polytrichoides and S. morrisonense, it can be consistently distinguished by a combination of diagnostic morphological characters (Table 2). These morphological differences were consistently observed across the examined populations and specimens. Furthermore, the ITS phylogeny recovered S. hengshanense as a distinct lineage that is sister to the clade comprising S. spiralifolium, S. sarmentosum and S. lineare, with strong support (Fig. 1). Together, these results provide complementary evidence for the recognition of S. hengshanense as a distinct species.

Morphologically, S. hengshanense is assignable to Sedum sect. Sedum sensu Fu and Ohba (2001), a section comprising more than 60 species, of which 49 are recorded from China. In recent years, approximately 20 new species assignable to this section have been described from East Asia, particularly China (Dai et al. 2025; Yi et al. 2025), indicating that the species diversity of this section remains incompletely documented. The discovery of S. hengshanense, therefore, further highlights the high taxonomic diversity of Sedum in East Asia and the need for continued field and taxonomic investigations in the region.

The ITS region was used in this study because sequence data are widely available for Sedum and the marker has been widely employed in phylogenetic studies of the genus. Its use also enabled relatively broad taxon sampling, based on sequences available in public databases. However, the use of a single molecular marker and limited intraspecific sampling, comprising one ITS sequence from each of two sampled populations, restricts our ability to assess population-level genetic variation and fine-scale phylogenetic relationships. Although the current ITS data support the inferred phylogenetic placement of S. hengshanense, broader population-level sampling encompassing all known populations, together with additional molecular markers, will be necessary to more comprehensively assess its infraspecific genetic diversity and phylogenetic coherence across its known range.

Taxonomic treatment Plantae Saxifragales Crassulaceae 991343C9-9635-56D8-85BC-08752E956CC5 Sedum hengshanense urn:lsid:ipni.org:names:77397020-1 N.Wei, X.D.Qiu, J.L.Xia & Q.F.Wang sp. nov. Figs 2 , 3 Chinese name.

衡山景天.

 Type.

China • Hunan: Nanyue District, Hengshan Mountain, Zhurong Peak, alt. 1245 m, 27.293782, 112.694611, on a rocky slope, 28 Apr 2025, J.L.Xia QS112 (holotype: HIB!; isotype: PE!).

 Diagnosis.

Sedum hengshanense is morphologically most similar to S. morrisonense, but differs in having papillate leaf margins (vs. non-papillate leaf margins), smaller and thinner leaves (7–10 × 1.5–2.0 mm, ca. 0.6 mm thick vs. leaves 10–15 × 2.5–3 mm, ca. 1 mm thick), longer basal leaf spurs (1.0–1.4 mm long vs. ca. 0.5 mm long) with an acuminate apex (vs. obtuse apex) and broadly spatulate to subtrapezoid nectar scales with an obtuse apex (vs. obovate nectar scales).

10.3897/phytokeys.279.192928.figure2 D5EFE7F5-83EC-599B-9E82-336DCA29F72F

Sedum hengshanense. A, B. Habitat on the open rocky slope; C. Habit in winter; D. Habit in spring; E, F. Mature plants at flowering stage; G. Mature plants under cultivation.

https://binary.pensoft.net/fig/1788071 Description.

Perennial herbs, entirely glabrous. Stems all fertile, succulent; older stems prostrate, bearing persistent withered leaves; young stems arising from older stems, 6–12 cm tall. Leaves alternate, imbricate, oblong-lanceolate, not twisted when young, 7–10 mm long, 1.5–2.0 mm wide, ca. 0.6 mm thick; apex acute; basal leaf spur acuminate, 1.0–1.4 mm long; margins papillate, especially conspicuous in the upper part; succulent. Inflorescence cymose, terminal, 3–5-branched, 2–4 cm in diam.; bracts leaf-like, similar to the leaves. Flowers numerous, sessile, actinomorphic, 0.9–1.2 cm long. Sepals 5, unequal, oblong-lanceolate, 2.5–5.0 mm long, 1.0–1.2 mm wide; apex shortly acuminate, conspicuous papillae; base spurred, spur ca. 0.8 mm long; green, fleshy. Petals 5, elliptic-lanceolate, 5–6 mm long, 1.2–1.5 mm wide; apex acuminate, shortly mucronate at the tip; basally connate for ca. 0.3 mm; yellow, fleshy. Stamens 10; antepetalous stamens 3.5–4.2 mm long, antesepalous stamens 3.9–4.4 mm long. Pollen tricolpate, ellipsoid, 26–28 μm long, 12–13 μm wide, exine with irregularly etched ornamentation. Carpels 5, erect, adaxially gibbous, lanceolate, basally connate for ca. 0.5 mm; ca. 4 mm long, ca. 0.9 mm wide; yellow. Nectar scales 5, broadly spatulate to subtrapezoid, apex obtuse, ca. 0.5 mm long, ca. 0.3 mm wide, white. Follicles obliquely divergent, gibbous, many-seeded. Seeds ellipsoid, surface densely papillate, 0.6–0.8 mm long, 0.2 mm wide.

10.3897/phytokeys.279.192928.figure3 D0F0A607-2877-56B7-8AA6-E65C6E0E8458

Sedum hengshanense. A, B. Habit; C. Fertile stem; D. Stem and leaves; E. Leaves; F, G. Upper portion of the leaf blade (showing marginal papillae); H. Inflorescence; I. Flower (sepals removed; inset showing the mucronate apex of petal); J. Sepals (inset showing papillate sepal apices); K. A petal and the stamens; L. Pistil and nectar scales; M. Carpel; N. Nectar scale; O. Pollen; P. Fruit; Q. Seed (not well developed).

https://binary.pensoft.net/fig/1788072 Phenology.

Flowering from April to May. Fruiting from May to June.

 Distribution and habitat.

Sedum hengshanense is distributed in Hengshan Mountain, central Hunan Province, China (Fig. 4), at elevations of 480–1250 m. It grows mainly on moist rocky cliffs, especially above 1000 m.

10.3897/phytokeys.279.192928.figure4 78FCD9D6-7480-541F-BCD5-F0C6BD1BD3A4

Distribution of Sedum hengshanense in Nanyue District, Hunan Province, China.

https://binary.pensoft.net/fig/1788073 Additional specimens examined

(paratypes). • Hunan: Nanyue District, Hengshan Mountain, Zhurong Peak, 27.293782°N, 112.694610°E, alt. 1230 m, on rocky slopes, 27 Apr 2025, J.L.Xia QS16 (HIB!); • the same locality, Hongqidianzhan, 27.315003°N, 112.672141°E, alt. 481 m, on rocky slopes, 6 May 2026, J.L.Xia QHN01 (HIB!); • the same locality, Huixianqiao, 27.29469°N, 112.69115°E, alt. 1200 m, on rocky slopes, 9 Jun 2026, J.L.Xia QHN02 (HIB!); • the same locality, Nantianmen, alt. 1100 m, on rocky slopes, 9 Jun 1964, C.M.Chen ex J.S.Yue 1595 (NAS!).

 Conservation status.

Three populations were documented in the wild, comprising fewer than 1,000 mature individuals. Two of these, located near the summit of Zhurong Peak, are vulnerable to anthropogenic disturbance associated with tourism development. Following the IUCN Red List Categories and Criteria (IUCN 2024), this new species is here assessed as Vulnerable (VU) under criteria C2a(i) and D1.

 Etymology.

The specific epithet ‘hengshanense’ refers to Hengshan Mountain (Hunan), the type locality where the species was discovered.

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The authors have declared that no competing interests exist.

 Ethical statement

No ethical statement was reported.

 Artificial Intelligence (AI) use

The authors accept full responsibility for the content of the manuscript, including the disclosure of any use of AI.

No AI tools were used in the preparation of this manuscript.

 Funding

This work was supported by National Key Research and Development Program of China (2024YFE0214500; 2024YFF1307400), National Natural Science Foundation of China (32200174; 32470225), Sino-Africa Joint Research Center, Chinese Academy of Sciences (SAJC202527ZD01), Support Programme to Plant Taxonomist from Chinese Academy of Sciences (CAS-TAX-24-040), as well as the Key R&D Programme of Yunnan Province (202403AC100028).

 Author contributions

Neng Wei, Qing-Feng Wang and Yu Xiong conceived the study. Jiang-Lin Xia, Guo-Ping Wang and Xiang-Dong Qiu performed field trips. Xiang-Dong Qiu, Feng-Di Zhang and Guo-Ping Tan conducted the measurements of morphological characters, SEM observations and phylogenetic analysis. Xiang-Dong Qiu, Feng-Di Zhang and Sheng-Wei Wang wrote the early version of manuscript. Neng Wei, Qing-Feng Wang and Yu Xiong reviewed the manuscript.

 Author ORCIDs

X.-D. Qiu https://orcid.org/0009-0007-2464-6921

F.-D. Zhang https://orcid.org/0009-0004-8943-8419

S.-W. Wang https://orcid.org/0000-0002-8785-5065

N. Wei https://orcid.org/0000-0002-0313-3912

Q.-F. Wang https://orcid.org/0000-0001-9143-8849

 Data availability

All of the data that support the findings of this study are available in the main text.

Xiang-Dong Qiu and Jiang-Lin Xia contributed equally to this work.