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This paper presents the result of consecutive floristic survey in Myanmar. Seven new species of Begonia (Begoniaceae), B. casseabri Y.H.Tan, M.B.Maw & H.B.Ding, B. persistens Y.H.Tan, M.B.Maw & H.B.Ding, B. latibracteata Y.H.Tan, M.B.Maw & H.B.Ding from Putao District, Kachin State, B. natmataungensis Y.H.Tan, M.B.Maw & H.B.Ding from Natma Taung National Park, Chin State, B. amnicola Y.H.Tan, M.B.Maw & H.B.Ding, B. sagaingensis Y.H.Tan, M.B.Maw & H.B.Ding and B. chindwinensis Y.H.Tan, M.B.Maw & H.B.Ding from Htamanthi Wildlife Sanctuary, Sagaing Region, are described and illustrated. All of the new species belongs to Begonia section Platycentrum (Klotzsch) A.DC. Detailed descriptions, colored photographs, habitat and distribution data for the seven new species are provided. A diagnostic key to species of Begonia sect. Platycentrum in Myanmar is presented.

—Amblyanthus chenii (Primulaceae; Myrsinoideae) is a new species discovered growing in the understory of primeval forests in Medog County, southeast Xizang, China and is described based on morphological evidence. This is the first generic record of Amblyanthus in China. The new species is most morphologically similar to A. multiflorus. Amblyanthus chenii can be easily distinguished from other congeneric species by various morphological differences. A phylogenetic analysis based on nuclear ribosomal ITS and six plastid markers indicated that A. chenii and Amblyanthopsis burmanica form a clade that is nested within the large pantropical genus Ardisia and is sister to Ardisia subgenus Crispardisia. The close relationship among Amblyanthus, Amblyanthopsis, and Ardisia subg. Crispardisia is strongly supported by their shared synapomorphy of crenulate leaves with marginal glands.

A distinct new species of Premna, P. caridantha which was discovered from Putao District, Kachin State, northern Myanmar, is described and illustrated here. It is characterized by having large and intricate paniculiform inflorescences which branch three times with the terminal branch formed by a spike-like thyrse, zygomorphic corolla with a short-incurved tube, and a bright yellowish spot on the middle lob of the lower corolla lip. The species is most similar to P. grandipaniculata but clearly differs in leaf shape and corolla characters. Premna caridantha is the fourth species having spike-like thyrses in Premna and the third new Premna species recently discovered from northern Myanmar.

A new species, Begonia depingiana from southern Yunnan, China, is described and illustrated. Morphologically, B. depingiana is similar to B. namkadingensis in habit, its tuberous rootstock and tepal number of the male and female flowers, but significantly differs by its 3 stigmas, and 3-locular ovary. It also resembles B. pellionioides in its pinnate leaf venation, but distinguished by the indumentum characters of its stem and ovary, tuberous rootstock, shorter plant, and unequally 3-winged capsule.

Alangium confertiflorum Y.H.Tan & H.B.Ding, a new species of Alangium section Alangium (Cornaceae) from China-Laos transboundary region, is described and illustrated here. The similarities and differences with closest allied species in the section Alangium, A. amplum W.J.de Wilde & Duyfjes and A. indochinense W.J.de Wilde & Duyfjes are discussed. The new species is assessed as Endangered (EN) following the IUCN Red List Categories and Criteria

We describe and illustrate Hoya gaoligongensis M.X. Zhao & Y.H. Tan (Apocynaceae, Asclepiadoideae), a new species native to mid-elevation moist evergreen broadleaved forests of Longling, Yunnan, SW China. We further compare the primary diagnostic morphological characters of H. gaoligongensis to its close relatives, H. yuennanensis Hand.-Mazz. and H. globulosa Hook.f. Compared with these two species, H. gaoligongensis has narrower long-oblanceolate leaves, much smaller lateral vein branch angles, and inconspicuous lateral veins. Although the corolla is similar in all three species, the relative positions of outer and inner corona lobe processes serve as a key character distinguishing these species. A side view of the corona of H. gaoligongensis shows that the outer lobe process is only slightly higher than the inner process, while the corresponding parts of H. yuennanensis are much higher, and those of H. globulosa are at almost equal heights. In addition, the glabrescent leaves and stems of both H. gaoligongensis and H. yuennanensis separate these taxa from H. globulosa.

Myanmar is botanically rich and floristically diverse: one of the world's biodiversity hotspots. However, Myanmar is still very unevenly explored, and until a plant checklist was published in 2003, relatively little work was done on its flora. This checklist included 11,800 species of spermatophytes in 273 families. Since this checklist was published, the botanical exploration of Myanmar has accelerated and there have been many additional publications. We therefore surveyed the literature of taxonomic contributions to Myanmar’s vascular flora over the last 20 years (2000–2019) and compiled a list of new and newly described taxa. Our list includes 13 genera, 193 species, 7 subspecies, 19 varieties, and 2 forms new to science; and 3 families, 34 genera, 347 species, 4 subspecies, 7 varieties, and 1 form newly recorded in Myanmar. Altogether, they represent 91 families and 320 genera. Most of the new discoveries belong to 15 families, with more than 25% (146 taxa) belonging to Orchidaceae. These new discoveries are unevenly distributed in the country, with about 41% of the newly discovered species described from Kachin State in northeast Myanmar. This reflects the incompleteness of our current knowledge of the flora of Myanmar and the urgent need for a greatly expanded effort. The completion of the flora of Myanmar requires more fieldwork from north to south, taxonomic studies on new and existing collections, and some mechanism that both coordinates the efforts of various international institutions and initiatives and encourages continued international cooperation. In addition, producing modern taxonomic treatments of the flora of Myanmar requires the participation of experts on all vascular plant families and genera. There is also an urgent need to attract young scientists to plant taxonomy, to work on inventories, identification, nomenclature, herbarium work, and comparative studies.

Two new species of Polyalthiopsis (Annonaceae), P. nigra Y.H. Tan & Bin Yang from Guangxi and Yunnan Provinces and P. xui Y.H. Tan & Bin Yang from Yunnan Province, are described and illustrated. P. nigra is morphologically similar to P. chinensis in having narrowly elliptic-oblong, lemon to yellowish green petals, but differs by having obovoid monocarps, a higher number of leaf secondary veins, leaf blades usually widest above the middle, and a lower ratio of leaf blade length to width. P. xui is morphologically similar to P. floribunda in having axillary inflorescences, 1–3(–4) flowers, elliptic leaves, and elliptic-ovate petals, but differs in the numbers of carpels per flower and ovules per carpel. The molecular phylogenetic analysis using five plastid markers confirm that the two new species belong to the genus Polyalthiopsis and show clear interspecific divergences between P. nigra and P. xui and between them and other species in the genus. Detailed descriptions, colored photographs, and habitat and distribution data for the two new species are provided. In addition, the fruit morphology of P. chinensis is described for the first time, based on living collections. Geographical distributions and a diagnostic key for all Polyalthiopsis species are also presented.

Buchanania yunnanensis was published based on a specimen consisting of a flowering branch without any leaves or fruits. Examination of morphological characters based on type specimens and our newly collected materials has shown that B. yunnanensis was incorrectly placed in Buchanania. At the time of description, and indicates that it is actually conspecific with Spondias pinnata. It is here reduced to a synonym of the latter species.

· Plant functional traits often show strong latitudinal trends. To explain these trends, studies have often focused on environmental variables, correlations with other traits that themselves show latitudinal trends, and phylogenetic conservatism. However, few studies have systematically disentangled the relative contributions of these factors.· Using partial coefficients of determination, R2, to analyze a dataset consisting of 9,370 plant species from East Asia, we investigated factors affecting fruit type (fleshy vs. dry fruits): environmental constrains (summarized by climate region), plant growth form, and phylogenetic conservatism. · Growth form and climate region are often cited in the literature as important explanations for the higher proportion of fleshy fruited species in the tropics. Nonetheless, in our analyses they explained only 1.7% and 0.3%, respectively, of the variance in fruit type. In contrast, phylogenetic conservatism explained 79.5%. Furthermore, phylogenetic conservatism was evenly distributed along the whole phylogeny, implying that fruit type reflects both ancient and recent phylogenetic relationships.· Our findings illustrate the value in parsing out the contributions of explanatory variables and phylogeny to the variance in species' traits. They also suggest that methods using the full phylogeny to calculate partial R2 give more power than traditional methods to explore the phylogenetic patterns of functional traits.

We conducted morphological and molecular analyses to describe a new species of Piperaceae, Piper semi-transparens, which was observed in Hainan, Guangdong and Guangxi Provinces, China. Detailed morphological comparisons between the newly discovered species and other members of Piper indicate that Piper semi-transparens is similar to P. bonii and P. bonii var. macrophyllum, from which it differs in having glabrous leaf blades; stem densely short and unbranched pubescent when young, glabrous when mature; veins 5(–7); stamens 2; stigmas 3, rarely 4; spikes color white when mature; floral bracts glabrous; pericarp white and semi-transparent. Molecular analyses based on the ITS marker of nuclear ribosomal DNA strongly support that P. semi-transparens is a new species in the genus Piper, most closely related to P. bonii and P. bonii var. macrophyllum.

Goniothalamus saccopetaloides Y.H. Tan & Bin Yang, a new species is described and illustrated from Laos. This species shows morphological similarities to G. yunnanensis W.T. Wang, but it differs from the latter by having almost fleshy, involute and saccate outer petals, subglobose monocarps, and single seeded monocarps. Goniothalamus cheliensis, and G. calvicarpus are new records for the Flora of Lao PDR. A key to Goniothalamus species indigenous to Laos is provided here.

Three new species of Begonia (B. chenii, B. putaoensis and B. crassitepala) belonging to Begonia section Platycentrum and a supplementary description of B. rheophytica with a detailed description of female flowers from Putao, Kachin State, Northern Myanmar, are described and illustrated. All the new species are endemic to Northern Myanmar and can be easily distinguished from other species among the section Platycentrum. A detailed description, photographs, habitat, distribution and a comparison with the most related allied species for all new species are provided.

Myanmar is known for its high species richness of genus Gastrochilus; however, most of them lack proper information for taxonomic revision. During four years of field investigation in Myanmar, two new distributional records were encountered, namely, G. arunachalensis and G. corymbosus and one species, i.e. G. pechei was rediscovered after its original description. The three species were not easy to interpret from the available original descriptions and types due to severely shrunk or poorly preserved specimens. Therefore, we hereby present more detailed illustrations and updated descriptions for these species, based on freshly collected materials.

Two taxa of Amomum (Zingiberaceae), Amomum erythranthum and Amomum ampliflorum, from Putao, Kachin State of Northern Myanmar are described and illustrated as new to science. Amomum erythranthum is morphologically similar to A. subulatum and A. nimkeyense in having similar yellow flowers, but can be distinguished by its reddish floral tube, red anther connective, red and pubescent fruit. Amomum ampliflorum is similar to A. maximum, A. dealbatum and A. odontocarpum in white flower, but differs in its longer inflorescence and much larger flower. Two species, Amomum pauciflorum and Wurfbainia microcarpum are recorded for the flora of Myanmar for the first time. Data on ecology, phenology, distribution, conservation status, similarities to the related taxa, as well as colour photographs and line drawings of the type, and voucher specimens are provided for all reported taxa.

The familial placements of Cyrtandromoea Zoll. and Wightia Wall., two small and enigmatic South‐East Asian genera, have long been controversial in Lamiales. Here we adopt a two‐step approach to resolve their phylogenetic relationships. We initially reconstructed a large‐scale phylogeny of Lamiales using six chloroplast markers (atpB, matK, ndhF, psbBTNH, rbcL, and rps4). The results showed that both Cyrtandromoea and Wightia emerged in the LMPO clade, including Lamiaceae, Mazaceae, Phrymaceae, Paulowniaceae, and Orobanchaceae. Based on the second set of six chloroplast markers (atpB, matK, ndhF, rbcL, rps16, and trnL‐F) and two nuclear ribosomal regions (external transcribed spacer and internal transcribed spacer) for the analyses focusing on the LMPO clade, our results revealed that Cyrtandromoea was consistently nested within Phrymaceae, whereas Wightia was supported as sister to Phrymaceae by the chloroplast DNA dataset or sister to Paulowniaceae by the nuclear ribosomal DNA dataset. Morphological and anatomical evidence fully supports the inclusion of Cyrtandromoea in Phrymaceae, and an updated tribal classification is done for Phrymaceae with five tribes, that is, Cyrtandromoeeae Bo Li, Bing Liu, Su Liu & Y. H. Tan, trib. nov., Diplaceae Bo Li, Bing Liu, Su Liu & Y. H. Tan, trib. nov., Leucocarpeae, Mimuleae, and Phrymeae. The conflicting phylogenetic position of Wightia indicated by different genome markers results in difficulty placing the genus in either Phrymaceae or Paulowniaceae. Considering the distinct morphological differences between Wightia and other families in the LMPO clade, we here propose a new family, Wightiaceae Bo Li, Bing Liu, Su Liu & Y. H. Tan, fam. nov., to accommodate it, which is the 26th family recognized in Lamiales.

Climate refugia are locations where plants are able to survive periods of regionally adverse climate. Such refugia may affect evolutionary processes and the maintenance of biodiversity. Numerous refugia have been identified in the context of Quaternary climate oscillations. With climate warming, there is an increasing need to apply insights from the past to characterize potential future refugia. Mountainous regions, due to the provision of spatially heterogeneous habitats, may contain high biodiversity, particularly important during climate oscillations. Here, we highlight the importance of mountaintops as climate refugia, using the example of high-mountain oaks which are distributed on the ranges of the Himalaya–Hengduan Mountains, and at high elevations in tropical rainforests. The occurrences of cold-adapted high-mountain oaks on mountaintops amidst tropical rainforest indicate that such locations are and will be climate refugia as global warming continues. We examine factors that predict the occurrence of future climate refugia on mountaintops using recognized historical refugia. Future research is needed to elucidate the fine-scale processes and particular geographic locations that buffer species against the rapidly changing climate to guide biodiversity conservation efforts under global warming scenarios.

Exotic plant invasion is an urgent issue occurring in the biosphere, which can be stimulated by environmental nitrogen (N) loading. However, the allocation and assimilation of soil N sources between leaves and roots remain unclear for plants in invaded ecosystems, which hampers the understanding of mechanisms behind the expansion of invasive plants and the co-existence of native plants. This work established a new framework to use N concentrations and isotopes of soils, roots, and leaves to quantitatively decipher intra-plant N allocation and assimilation among plant species under no invasion and under the invasion of Chromolaena odorata and Ageratina adenophora in a tropical ecosystem of SW China. We found that the assimilation of N derived from both soil ammonium (NH4+) and nitrate (NO3-) were higher in leaves than in roots for invasive plants, leading to higher leaf N levels than native plants. Compared with the same species under no invasion, most native plants under invasion showed higher N concentrations and NH4+ assimilations in both leaves and roots, and increases in leaf N were higher than in root N for native plants under invasion. These results inform that preferential N allocation, dominated by NH4+-derived N, to leaves over roots as an important N-use strategy for plant invasion and co-existence in the studied tropical ecosystem.

Costus chinensis and C. oblongus (Costaceae) has been previously placed in synonymy under C. lacerus. Our critical examination of herbarium specimens including type material demonstrates that they are morphologically distinct from each other. Therefore, the independent specific status of C. chinensis and C. oblongus is reinstated. According to recent studies, Costus chinensis as well as other two Chinese species, C. oblongus and C. viridis, should be transferred to Hellenia. Thus, a new name for C. chinensis, and two new combinations are proposed. A detailed description of C. chinensis along with a distribution map of three allied species is also provided.

The complexity of global biodiversity in the tropical Indochina Peninsula and subtropical China bioregions has fascinated biologists for decades, but little is known about the spatiotemporal patterns in these regions. Accordingly, the aims of present study were to investigate the evolutionary and distribution patterns of Engelhardia in these regions and establish a model for examining biogeographic patterns and geological events throughout the tropical Indochina Peninsula and subtropical China. The effects of geological events occurring in the area between the Indochina Peninsula and subtropical China bioregions on the two trees species (i.e., E. roxburghiana and E. fenzelii) were evaluated. A robust phylogenetic framework of 884 individuals from 79 populations was used to generate time-calibrated cytoplasmic and nuclear phylogenetic frameworks based on cpDNA, nrDNA, and nSSR data, respectively. When considered along with ancestral area reconstructions, the genetic data were also used to assess and reconstruct the species' population genetic structure and diversity. These analyses yielded important information about the (1) historical distribution relationships between the tropical and subtropical flora of China; (2) effects of the East Asian summer monsoon (EASM) on the evolutionary history of Asia's plants; and (3) importance of biogeography in conservation planning. Although cytoplasmic-nuclear discordance indicated cpDNA and nrDNA were subject to distinct evolutionary mechanisms that reflected respective evolutionary histories of the plastid and nuclear genomes of prior demographic and biogeographic events. The tropical elements of Engelhardia occupied the Indochina Peninsula during the early Eocene, whereas the subtropical elements were transformed from the tropical elements during Miocene cooling and the onset of the EASM at the Oligocene-Miocene boundary, intensified during the late Miocene and Pliocene, facilitating the transformation of Engelhardia from the tropical Indochina Peninsula to subtropical China. Demographic history provided insights into prominent planning frameworks in conservation biology, namely that subtropical China functioned as a refugium during past climate oscillations and will continue to serve in this capacity in the future.

Transboundary conservation is playing an increasingly important role in maintaining ecosystem integrity and halting biodiversity loss caused by anthropogenic activities. However, lack of information on species distributions in transboundary regions and understanding of the threats in these areas impairs conservation. We developed a spatial conservation plan for the transboundary areas between Yunnan province, southwestern China, and neighboring Myanmar, Laos, and Vietnam in the Indo-Burma biodiversity hotspot. To identify priority areas for conservation and restoration, we determined species distribution patterns and recent land-use changes and examined the spatiotemporal dynamics of the connected natural forest, which supports most species. We assessed connectivity with equivalent connected area (ECA), which is the amount of reachable habitat for a species. An ECA incorporates the presence of habitat in a patch and the amount of habitat in other patches within dispersal distance. We analyzed 197,845 locality records from specimen collections and monographs for 21,004 plant and vertebrate species. The region of Yunnan immediately adjacent to the international borders had the highest species richness, with 61% of recorded species and 56% of threatened vertebrates, which suggests high conservation value. Satellite imagery showed the area of natural forest in the border zone declined by 5.2% (13,255 kmPlaneación de la Conservación en las Fronteras de China con Myanmar, Laos y Vietnam Resumen La conservación transfronteriza cada vez juega un papel más importante en la preservación de la integridad del ecosistema y en el freno a la pérdida local de la biodiversidad causada por las actividades antropogénicas. Sin embargo, la falta de información sobre la distribución de las especies en las regiones transfronterizas y de la comprensión de las amenazas en estas áreas obstaculiza la conservación. Desarrollamos un plan de conservación espacial para las áreas transfronterizas entre la provincia de Yunnan, al suroeste de China, y los países vecinos Myanmar, Laos y Vietnam localizadas en el punto caliente de biodiversidad Indo-Burma. Para identificar las áreas prioritarias para la conservación y la restauración, determinamos los patrones de distribución de las especies y los recientes cambios en el uso de suelo y examinamos las dinámicas espaciotemporales del bosque natural conectado, el cual mantiene a la mayoría de las especies. Evaluamos la conectividad con el área equivalente conectada (AEC), que es la cantidad de hábitat accesible para una especie. Un AEC incorpora la presencia del hábitat en un fragmento y la cantidad de hábitat en otros fragmentos dentro de la distancia de dispersión. Analizamos 197,845 registros de localidades desde colecciones de especímenes y monografías para 21,004 especies de plantas y de vertebrados. La región de Yunnan inmediatamente adyacente a las fronteras internacionales tuvo la riqueza de especies más alta con el 61% de las especies registradas y el 56% de los vertebrados amenazados, lo que sugiere un elevado valor de conservación. Las imágenes satelitales mostraron que el área del bosque natural en la zona fronteriza declinó en un 5.2% (13,255 km跨境保护在维持生态系统完整和阻止人类活动引起的生物多样性丧失方面起着重要的作用。然而, 跨境区域的物种分布信息和所受威胁的认识都很匮乏, 这不利于进一步的保护。在印-缅生物多样性热点地区, 我们为中国云南省及其毗邻的缅甸, 老挝和越南的跨境区域提供了一个空间保护计划。通过分析物种分布格局, 近期土地利用变化以及为大多数物种提供了生境的天然林的连通性时空动态, 我们识别了该跨境区域的保护和恢复优先区。我们利用等同连接面积(ECA)指数来评估连通性。该指数可以测量一个物种在其扩散距离范围内可以到达的总的生境数量。我们从标本和专著中收集了21,004个植物和脊椎动物物种并分析了197,845条分布记录, 结果显示云南省边境地区具有最高的物种丰富度, 61%的已记录的物种和56%的受威胁脊椎动物分布在云南边境地区, 这表明边境地区具有高的保护价值。卫星影像分析显示, 从1995至2018年, 跨境区域天然林面积减少了5.2% (13,255 km2), 而单一种植的人工林面积增加了92.4%, 灌丛面积增加了10.1%, 农田面积增加了6.2%。由此引起的连通的天然林面积的下降减少了生境数量, 这对扩散能力较弱的森林特化物种的影响尤为明显。中-越边境上的连通性下降最为严重。许多优先区跨越了国界线, 这表明了建立跨境保护地的需求和潜力。我们的结果阐明了双边或多边合作保护生物多样性的重要性, 同时也为该跨境区域未来的保护规划和实践提供了指导。.

Zingiber porphyrochilum Y.H. Tan & H.B. Ding sp. nova (Zingiberaceae) from Yunnan, China is described and illustrated. It is similar to Z. densissimum in its bilobed ligule and flower shape but differs from it by having a longer clumped pseudostem (1.5–2.5 m tall vs. solitary, 0.4–0.7 m tall), longer ligules (3–11 mm long vs. ca. 3 mm long), brownish yellow corolla lobes (vs. pure white), labellum and lateral staminodes brownish yellow at the base, and bright clear red to dark purplish towards the apex and margins (vs. pure white).

Biodiversity managements are always hot topics in China that harbors so much hyper-biodiversity. However, biodiversity loss is continuing as economic growth is accelerating during recent decades. Questions that need to be addressed with regard to the conflict between biodiversity conservation and economic growth are: how much conservation effort is required and what measures are necessary to reconcile conflicts. Here we evaluate the phenomenon and conservation status of representative of the rare plants with important economic values in tropical China. They are facing the danger of extinction, even are disappearing as they are discovered. This topic enables us to propose conservation measures to resolve the dilemma that continued biodiversity loss is linked closely with economic growth. A combination of ex situ conservation, in situ conservation and in-depth surveys, is necessary to protect biodiversity in the tropical China. Insights gained from current conflict will permit a greater understanding of the rare plants with significant evolutionary and ecological roles but which are threatened by economic development, thus enabling the relevant departments to develop and implement appropriate conservation policies.

1. Exotic plant invasion has been changing the vegetation composition and function of terrestrial ecosystems. Nitrogen (N) and phosphorus (P) are often the limiting nutrients for terrestrial plants. However, under invasive pressure, in situ plant N and P usage mechanisms remain poorly understood but are pivotal for a better understanding of plant invasion and coexistence in invaded ecosystems. 2. Nitrogen and P concentrations, natural N-15 abundance (delta N-15 values) were investigated in leaves and soils under different invasive pressures (here expressed as the biomass percentages of invasive plants in each plot) for two invasive species (Chromolaena odorata and Ageratina adenophora) in Xishuangbanna in tropical China. 3. Soil N and P concentrations revealed the relatively N-rich but P-poor status of our study site. Under invasion, soil inorganic N (dominated by ammonium) and available P did not increase significantly. The leaf N and P of invasive plants increased, while leaf N increased but P decreased for native species. Natural delta N-15 mass balance between leaves and soil inorganic N sources revealed that ammonium dominated N utilization in both natives and invaders. Invasive plants showed ammonium utilization with increasing leaf N levels, while native plants under no invasion showed nitrate utilization with increasing leaf N levels. 4. Synthesis. Increased soil ammonium availability contributed to preferential ammonium utilization by invasive plants and elevated ammonium utilization in natives, but the P competition of natives decreased in invaded ecosystems. These novel insights into nutrient dynamics in invaded ecosystems enhance our understanding of plant invasion and coexistence mechanisms.

Seed dormancy profiles are available for the major vegetation regions/types on earth. These were constructed using a composite of data from locations within each region. Furthermore, the proportion of species with nondormant (ND) seeds and the five classes of dormancy is available for each life form in each region. Using these data, we asked: will the results be the same if many species from a specific area as opposed to data compiled from many locationsare considered? Germination was tested for fresh seeds of 358 species in 95 families from the Xishuangbanna seasonal tropical rainforest (XSTRF): 177 trees, 66 shrubs, 57 vines and 58 herbs. Seeds of 12.3% of the species were ND, and 0.3, 14.8, 60.6, 12.0 and 0% of the species had morphological (MD), morphophysiological (MPD), physiological (PD), physical (PY), and combinational (PY + PD) dormancy, respectively. PD was more important than ND in all life forms, PY was highest in shrubs, MD was not important in any life form and MPD was most common for herb and vines. The seed dormancy profile for XSTRF differs considerably from the composite profile for this vegetation type worldwide, most obviously in ND being much lower and PD much higher in XSTRF.

Dendrobium naungmungense, a new species from Naungmung, Kachin State, North Myanmar, is described and illustrated. It is morphologically similar to D. ciliatilabellum and D. vexabile, but the epichile is oblong with three long-ciliate laminae and the column wing has significant denticulation. A preliminary risk-of-extinction assessment shows that the new species should be regarded as Critically Endangered (CR) according to the IUCN Red List Categories and Criteria.

Hedychium putaoense Y.H. Tan & H.B. Ding, a new species of Zingiberaceae from Putao, Kachin state, Northern Myanmar, is described and illustrated. It is similar to H. densiflorum Wall. and H. longipedunculatum A.R.K. Sastry & D.M. Verma, but differs by its very small bract (4–6 × 2.5–3 mm vs. 18–19 × 5–5.5 mm and ca. 11 × 7 mm, respectively), semicircle and dark red bracteole, orange flower and broadly falcate to lanceolate lateral staminodes.

Aristolochia sinoburmanica Y.H.Tan & B.Yang, a new species of Aristolochiaceae from Putao, Kachin State, Myanmar, is described and illustrated. According to morphology (strongly curved perianth, 3-lobed limb, as well as 3-lobed gynostemium, anthers 6, adnate in 3 pairs to the base of gynostemium, opposite to the lobes), the species belongs to Aristolochia subgenus Siphisia. It is morphologically similar to A. faviogonzalezii, A. hainanensis, A. tonkinensis, A. saccata and A. xuanlienensis. The major differences between them are outlined and discussed. A detailed description, along with line drawings, photographs, habitat, distribution and conservation status, as well as a comparison to morphologically similar species, are also provided.

Recent molecular and morphological studies have clarified generic circumscriptions in Annonaceae tribe Miliuseae and resulted in the segregation of disparate elements from the previously highly polyphyletic genus Polyalthia s.l. Several names in Polyalthia nevertheless remain unresolved, awaiting assignment to specific genera, including Polyalthia litseifolia . Phylogenetic analyses of seven chloroplast regions ( atpB-rbcL , matK , ndhF , psbA-trnH , rbcL , trnL-F , ycf1 ; ca. 8.3 kb, 116 accessions, including representatives of all currently accepted genera in subfamily Malmeoideae) unambiguously placed Polyalthia litseifolia in a clade with three accessions from Thailand, which have previously been shown to represent an undescribed genus sister to the Neotropical clade ( Desmopsis , Sapranthus , Stenanona , Tridimeris ) in the predominantly Asian tribe Miliuseae. The collective clade is sister to Meiogyne . Polyalthia litseifolia shares several diagnostic characters with most species in the Neotropical genera and Meiogyne , including: petals that are similar in shape and size in both whorls; multiple ovules per ovary in one or two rows; and lamelliform endosperm ruminations. It is distinct in being deciduous, bearing subpetiolar buds and having inflorescences growing from the leaf scar of the dropped leaves. Morphological comparisons and phylogenetic analyses corroborate its recognition as a new genus, which is formally described and illustrated here as Wuodendron . Polyalthia litseifolia is furthermore found to be conspecific with Desmos praecox , and the latter name is used as the basis for the name of the type. Molecular divergence time estimates under an uncorrelated lognormal relaxed clock place the Wuodendron -Neotropical clade split within the Miocene (ca. 14–12 Ma), highlighting the importance of post-boreotropical dispersal and vicariance in shaping intercontinental tropical disjunctions in Annonaceae.

Alseodaphne is a genus of timber trees (ca. 40 spp.) belonging to the Persea group of the Lauraceae. It is widely distributed in tropical Asia, but is often confused with Dehaasia and Nothaphoebe, and the systematics of the genus is unclear. Here, the complete chloroplast genome sequences of A. semecarpifolia will be reported, the type species of Alseodaphne, and two China-endemic species, A. gracilis and A. huanglianshanensis. The three plastomes were 153 051 bp, 153 099 bp and 153 070 bp, respectively. Comparative genomic analyses indicate that the three Alseodaphne plastomes have similar genome size and those are very different with previously published plastomes of Lauraceae in length. The length difference is directly caused by inverted repeats expansion/contraction. Four highly variable loci including psbD-trnM, ndhF-rpl32, rpl32-trnL and ycf1 among the three Alseodaphne species were identified as useful plastid candidate barcodes for Alseodaphne and Lauraceae species. Phylogenetic analyses based on 12 complete plastomes of Lauraceae species confirm a monophyletic Persea group comprising species of Alseodaphne, Phoebe, Persea and Machilus.

Coelogyne magnifica (Orchidaceae), a new species from Putao, Kachin State, Myanmar, is described and illustrated. It belongs to Coelogyne section Ocellatae Pfitzer & Kraenzl. and it is morphologically similar to Coelogyne corymbosa and C. taronensis, but can be distinguished from these species by its larger flowers, lanceolate sepals and petals, a narrowly ovate lip, which has two bright yellow patches surrounded by shiny brownish red and two fimbriate or erose-lacerate lateral keels on the lip. The major differences between these species are outlined and discussed.

Available plastomes of the Lauraceae show similar structure and varied size, but there has been no systematic comparison across the family. In order to understand the variation in plastome size and structure in the Lauraceae and related families of magnoliids, we here compare 47 plastomes, 15 newly sequenced, from 27 representative genera. We reveal that the two shortest plastomes are in the parasitic Lauraceae genus Cassytha, with lengths of 114,623 (C. filiformis) and 114,963 bp (C. capillaris), and that they have lost NADH dehydrogenase (ndh) genes in the large single-copy region and one entire copy of the inverted repeat (IR) region. The plastomes of the core Lauraceae group, with lengths from 150,749 bp (Nectandra angustifolia) to 152,739 bp (Actinodaphne trichocarpa), have lost trnI-CAU, rpl23, rpl2, a fragment of ycf2, and their intergenic regions in IRb region, whereas the plastomes of the basal Lauraceae group, with lengths from 157,577 bp (Eusideroxylon zwageri) to 158,530 bp (Beilschmiedia tungfangensis), have lost rpl2 in IRa region. The plastomes of Calycanthus (Calycanthaceae, Laurales) have lost rpl2 in IRb region, but the plastome of Caryodaphnopsis henryi (Lauraceae) remain intact, as do those of the nonLaurales magnoliid genera Piper, Liriodendron, and Magnolia. On the basis of our phylogenetic analysis and structural comparisons, different loss events occurred in different lineages of the Laurales, and fragment loss events in the IR regions have largely driven the contraction of the plastome in the Lauraceae. These results provide new insights into the evolution of the Lauraceae as well as the magnoliids as a whole.

Polyalthia yingjiangensis sp. nov. is described from the China/Myanmar border. It is distinct in having outer petals that are much shorter than the inner petals and having a very long pedicel. It is most similar to P. miliusoides I.M. Turner, but differs in having perianth parts that are glabrous adaxially and pubescent abaxially, thicker and sparsely pubescent pedicels, as well as verrucose and darker monocarps.

In the present study, we describe and illustrate a new species, Premna bhamoensis Y. T. Tan & B. Li (Lamiaceae), from Myanmar. In the 1980s, this species was transplanted from Bhamo County in northeastern Myanmar to the Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences. The species shows striking morphological similarity to P. menglaensis B. Li, and thus, has been misidentified as the latter for a long period of time. However, morphological comparison revealed that P. bhamoensis is distinct from P. menglaensis in many aspects. Moreover, literature survey and specimen examinations also indicated that P. bhamoensis is undoubtedly different from all seven known congenetic species recorded from Kachin State, Myanmar, and a key for their identification has been provided in this paper.

A phylogenetic analysis based on 18S nuclear ribosomal DNA and four plastid markers (atpB, matK, rbcL and trnLF) strongly supports the position of a new genus in Euphorbiaceae tribe Epiprineae (subfamily Acalyphoideae). Tsaiodendron dioicum gen. nov., sp. nov. is described and illustrated here as a new genus and species from Yunnan province, south-western China. The phylogenetic position of the new taxon is also supported by morphological and palynological evidence. Tsaiodendron is a distinct lineage sister to Cladogynos in tribe Epiprineae and is easily distinguished from related members of the tribe by the sexual system, inflorescence arrangement and presence of disc glands in the pistillate flower. Molecular divergence dating analysis based on matK, rbcL and trnL-F sequences suggests that Tsaiodendron originated in the late Miocene 10.42 Mya (95% HPD: 5.23-18.88 Mya). The origin of Tsaiodendron may be correlated with the Red River incision from south-western China. Tribe Epiprineae are shown to be monophyletic and phylogenetic relationships and evolutionary trends in the sexual system are also discussed based on our phylogenetic results.

Alseodaphnopsis maguanensis and A. putaoensis, two new species of Alseodaphnopsis (Lauraceae) from southwestern China (Yunnan Province) and northern Myanmar (Kachin State), are here described and illustrated based on both morphological and molecular evidence. They are morphologically similar to Alseodaphnopsis rugosa and phylogenetically closely related to A. rugosa and A. hainanensis respectively. Their preliminary conservation status is also estimated according to the IUCN Red List Categories and Criteria.

Enhanced efficacy in species delimitation is critically important in biology given the pending biodiversity crisis under global warming and anthropogenic activity. In particular, delineation of traditional classifications in view of the complexity of species requires an integrative approach to effectively define species boundaries, and this is a major focus of systematic biology. Here, we explored species delimitation of Engelhardia in tropical and subtropical Asia. In total, 716 individuals in 71 populations were genotyped using five chloroplast regions, one nuclear DNA region (nrITS), and 11 nuclear simple sequence repeats (nSSR). Phylogenetic trees were constructed and relationships among species were assessed. Molecular analyses were then combined with 14 morphological characteristics of 720 specimens to further explore the species boundaries of Engelhardia. Integrating phylogenetic and morphological clusters provided well-resolved relationships to delineate seven species. The results suggested that: first, that E. fenzelii, E. roxburghiana, E. hainanensis, E. apoensis, and E. serrata are distinct species; second, E. spicata var. spicata, E. spicata var. aceriflora, E. spicata var. colebrookeana, and E. rigida should be combined under E. spicata and treated as a species complex; third, E. serrata var. cambodica should be raised to species level and named E. villosa. We illuminated that bias thresholds determining the cluster number for delimiting species boundaries were substantially reduced when morphological data were incorporated. Our results urge caution when using the concepts of subspecies and varieties in order to prevent confusion, particularly with respect to species delimitation for tropical and subtropical species. In some cases, re-ranking or combining subspecies and/or varieties may enable more accurate species delimitation.

Marsdenia yarlungzangboensis(Apocynaceae, Asclepiadoideae), a new species from Motuo County, southeastern Xizang of China, is described and illustrated. It is morphologically similar toM. medogensis,M. teniiandM. yuei, the major differences between the new species and the morphological relatives are outlined and discussed. A diagnostic key to the new species and its closely related species in China is provided.