Pub Date : 2024-09-11DOI: 10.1093/botlinnean/boae059
João A M Carmo, Marcelo Reginato, Sandra V Sobrado, Laila M Miguel, Steven B Janssens, Steven Dessein, Roberto M Salas, André O Simões
The Spermacoce clade, found primarily in the Americas, poses taxonomic challenges, notably in the unclear boundaries of Borreria and Spermacoce. These genera intertwine with smaller, morphologically distinct ones, including Psyllocarpus, a Brazilian endemic redefined into two sections. Psyllocarpus sect. Psyllocarpus, being based on the original genus delineation, encompasses nine species in the Cerrado and campo rupestre of eastern Brazil, and P. sect. Amazonica includes three species in the Amazonian campinas, while Psyllocarpus intermedius remains unclassified. Our phylogenetic study, sampling extensively across the Spermacoce clade for nuclear ribosomal (ETS and ITS) and plastid (rps16 and trnL-trnF) DNA regions and using a variety of approaches to analyse our dataset, revealed that Psyllocarpus is not monophyletic. Notably, P. campinorum (representing P. sect. Amazonica) and P. intermedius are distinct lineages in the Spermacoce clade but fall outside Psyllocarpus. Conversely, P. sect. Psyllocarpus forms a well-supported clade, closely related to Staelia. Therefore, Psyllocarpus has to be circumscribed based on its original concept, excluding P. sect. Amazonica and P. intermedius. This defines the genus as a distinct, easily diagnosable taxon. We provide a synoptic list of names and nomenclatural types of Psyllocarpus to formalize our results, with an updated description of the genus.
{"title":"There and back again: molecular phylogenetics of the Brazilian endemic Psyllocarpus (Rubiaceae: Spermacoceae) supports a circumscription of the genus based on its original concept","authors":"João A M Carmo, Marcelo Reginato, Sandra V Sobrado, Laila M Miguel, Steven B Janssens, Steven Dessein, Roberto M Salas, André O Simões","doi":"10.1093/botlinnean/boae059","DOIUrl":"https://doi.org/10.1093/botlinnean/boae059","url":null,"abstract":"The Spermacoce clade, found primarily in the Americas, poses taxonomic challenges, notably in the unclear boundaries of Borreria and Spermacoce. These genera intertwine with smaller, morphologically distinct ones, including Psyllocarpus, a Brazilian endemic redefined into two sections. Psyllocarpus sect. Psyllocarpus, being based on the original genus delineation, encompasses nine species in the Cerrado and campo rupestre of eastern Brazil, and P. sect. Amazonica includes three species in the Amazonian campinas, while Psyllocarpus intermedius remains unclassified. Our phylogenetic study, sampling extensively across the Spermacoce clade for nuclear ribosomal (ETS and ITS) and plastid (rps16 and trnL-trnF) DNA regions and using a variety of approaches to analyse our dataset, revealed that Psyllocarpus is not monophyletic. Notably, P. campinorum (representing P. sect. Amazonica) and P. intermedius are distinct lineages in the Spermacoce clade but fall outside Psyllocarpus. Conversely, P. sect. Psyllocarpus forms a well-supported clade, closely related to Staelia. Therefore, Psyllocarpus has to be circumscribed based on its original concept, excluding P. sect. Amazonica and P. intermedius. This defines the genus as a distinct, easily diagnosable taxon. We provide a synoptic list of names and nomenclatural types of Psyllocarpus to formalize our results, with an updated description of the genus.","PeriodicalId":9178,"journal":{"name":"Botanical Journal of the Linnean Society","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-09DOI: 10.1093/botlinnean/boae055
Jeffrey G Duckett, Karen S Renzaglia, Silvia Pressel
The recent realization that bryophyte sporophytes are homoiohydric enabled the present analysis of morphological features specifically associated with poikilohydry. The only morphological feature absolutely diagnostic of poikilohydry is schizolytic intercellular spaces. In vascular plants these are gas-filled from the outset, but in bryophytes are liquid-filled initially. They remain in this condition in liverwort gametophytes but become gas-filled following stomatal opening in hornworts and mosses. These have fixed apertures and are completely unresponsive to environmental cues. Stomata in Devonian fossils may have had similarly fixed apertures. Unistratose lamellae, characteristic of moss and liverwort leaves and pteridophyte gametophytes, are optimal structures for reversible cell shrinkage and recovery accompanying de- and rehydration. In 1 M sucrose, gametophytic tissues and filmy fern leaves undergo shrinkage, whereas sporophyte cells plasmolyse. Under extreme desiccation, hydroids are the only bryophyte cells to undergo cavitation. Like bryophytes, desiccation-tolerant streptophyte algae undergo reversible cell shrinkages. Mucilage secretion is unimportant in bryophyte desiccation biology and developmental differences rule out homology between the mucilage clefts and stomata in hornworts and Blasiales. Elaborate placental walls in basal liverwort lineages and a stomatal toolkit in the capsule walls of Haplomitrium suggest that liverworts’ ancestors may have had more complex sporophytes than those in extant taxa.
最近，人们认识到叶绿体孢子体是同水生的，因此能够对与水生形态相关的形态特征进行分析。唯一能绝对诊断出水生现象的形态特征是分裂的细胞间隙。在维管植物中，细胞间隙从一开始就是充满气体的，但在红叶植物中，细胞间隙最初是充满液体的。肝草配子体的细胞间隙保持这种状态，但角草和苔藓的细胞间隙在气孔打开后会变成充满气体。这些气孔孔径固定，对环境线索完全没有反应。泥盆纪化石中的气孔可能也有类似的固定孔径。苔藓和肝草叶片以及翼叶植物配子体所特有的单丝状薄片是细胞在脱水和再水化过程中可逆收缩和恢复的最佳结构。在 1 M 蔗糖中，配子体组织和丝状蕨类叶片会发生收缩，而孢子体细胞则会溶解。在极度干燥的情况下，水螅是唯一会发生空洞化的叶绿体细胞。与红叶植物一样，耐干燥的链格藻也会发生可逆的细胞收缩。粘液分泌在红叶植物的干燥生物学中并不重要，而且发育上的差异也排除了角叉菜和褐藻的粘液裂隙与气孔之间存在同源性的可能性。肝草基系中复杂的胎盘壁和 Haplomitrium 的蒴果壁中的气孔工具包表明，肝草的祖先可能拥有比现生类群更复杂的孢子体。
{"title":"Reflections on the absence of stomata on the gametophyte generation of extant land plants: a focus on poikilohydry","authors":"Jeffrey G Duckett, Karen S Renzaglia, Silvia Pressel","doi":"10.1093/botlinnean/boae055","DOIUrl":"https://doi.org/10.1093/botlinnean/boae055","url":null,"abstract":"The recent realization that bryophyte sporophytes are homoiohydric enabled the present analysis of morphological features specifically associated with poikilohydry. The only morphological feature absolutely diagnostic of poikilohydry is schizolytic intercellular spaces. In vascular plants these are gas-filled from the outset, but in bryophytes are liquid-filled initially. They remain in this condition in liverwort gametophytes but become gas-filled following stomatal opening in hornworts and mosses. These have fixed apertures and are completely unresponsive to environmental cues. Stomata in Devonian fossils may have had similarly fixed apertures. Unistratose lamellae, characteristic of moss and liverwort leaves and pteridophyte gametophytes, are optimal structures for reversible cell shrinkage and recovery accompanying de- and rehydration. In 1 M sucrose, gametophytic tissues and filmy fern leaves undergo shrinkage, whereas sporophyte cells plasmolyse. Under extreme desiccation, hydroids are the only bryophyte cells to undergo cavitation. Like bryophytes, desiccation-tolerant streptophyte algae undergo reversible cell shrinkages. Mucilage secretion is unimportant in bryophyte desiccation biology and developmental differences rule out homology between the mucilage clefts and stomata in hornworts and Blasiales. Elaborate placental walls in basal liverwort lineages and a stomatal toolkit in the capsule walls of Haplomitrium suggest that liverworts’ ancestors may have had more complex sporophytes than those in extant taxa.","PeriodicalId":9178,"journal":{"name":"Botanical Journal of the Linnean Society","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219979","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-28DOI: 10.1093/botlinnean/boae045
Maarten J M Christenhusz, Rafaël Govaerts
Species go extinct each day, most without notice. The current human-induced extinction rate is up to 700 times higher than the background rate. Extinctions are not different for plants, animals, or fungi, although botanical and invertebrate extinctions are much more poorly documented than those of charismatic vertebrates. In a recent book on extinct plants (Christenhusz & Govaerts, 2023), an overview of botanical extinctions since 1753 was presented, listing which species became extinct and the probable reason for their extinction. As most have a date when they were last documented, a timeline of extinction can also be compiled based on these data. This timeline shows an increase from 1890 to 1940, but a decline in new recorded extinctions after the 1980s, which is likely a result of taxonomic impediment. Extinction rates before 1800 are impacted by the lack of data (here named Berkeley extinction). It can be concluded that extinction is highest in biodiversity-rich areas with high human influence (extinction hotspots). Two new combinations and a new name are proposed here, showing the importance of taxonomy to conservation. Although anthropogenic plant extinction is a global phenomenon, areas of particular concern are the Hawaiian Islands, southern Africa, Australia, the Indian Subcontinent, Southeast Asia, and Brazil. Extinctions have been mainly caused by land clearing for agriculture and urbanization, invasive feral animals, mining, river dams, diseases, and poaching. We predict that the unusual weather patterns associated with rapid climate change may result in more plant extinctions. Reintroduction, even if a species persists in cultivation, is not always possible due to lack of suitable remaining habitat where threats are decreased or removed. Successful reintroduction cannot be guaranteed. It is costly and usually dependent on short-term funding, after which these efforts may be in vain. Protection of species in their natural habitat is much more cost-effective in the long term. Sometimes, rescued plants should be introduced in similar habitats outside their natural range where the threats are absent. This follows the programmes of assisted migration for climate change mitigation, but this can also be assisted introduction to prevent extinction. Protection of critically endangered species that have naturalized outside their native range should also be considered.
{"title":"Plant extinction in the Anthropocene","authors":"Maarten J M Christenhusz, Rafaël Govaerts","doi":"10.1093/botlinnean/boae045","DOIUrl":"https://doi.org/10.1093/botlinnean/boae045","url":null,"abstract":"Species go extinct each day, most without notice. The current human-induced extinction rate is up to 700 times higher than the background rate. Extinctions are not different for plants, animals, or fungi, although botanical and invertebrate extinctions are much more poorly documented than those of charismatic vertebrates. In a recent book on extinct plants (Christenhusz & Govaerts, 2023), an overview of botanical extinctions since 1753 was presented, listing which species became extinct and the probable reason for their extinction. As most have a date when they were last documented, a timeline of extinction can also be compiled based on these data. This timeline shows an increase from 1890 to 1940, but a decline in new recorded extinctions after the 1980s, which is likely a result of taxonomic impediment. Extinction rates before 1800 are impacted by the lack of data (here named Berkeley extinction). It can be concluded that extinction is highest in biodiversity-rich areas with high human influence (extinction hotspots). Two new combinations and a new name are proposed here, showing the importance of taxonomy to conservation. Although anthropogenic plant extinction is a global phenomenon, areas of particular concern are the Hawaiian Islands, southern Africa, Australia, the Indian Subcontinent, Southeast Asia, and Brazil. Extinctions have been mainly caused by land clearing for agriculture and urbanization, invasive feral animals, mining, river dams, diseases, and poaching. We predict that the unusual weather patterns associated with rapid climate change may result in more plant extinctions. Reintroduction, even if a species persists in cultivation, is not always possible due to lack of suitable remaining habitat where threats are decreased or removed. Successful reintroduction cannot be guaranteed. It is costly and usually dependent on short-term funding, after which these efforts may be in vain. Protection of species in their natural habitat is much more cost-effective in the long term. Sometimes, rescued plants should be introduced in similar habitats outside their natural range where the threats are absent. This follows the programmes of assisted migration for climate change mitigation, but this can also be assisted introduction to prevent extinction. Protection of critically endangered species that have naturalized outside their native range should also be considered.","PeriodicalId":9178,"journal":{"name":"Botanical Journal of the Linnean Society","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142220014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-08DOI: 10.1093/botlinnean/boae041
Maria A Polezhaeva, Makar V Modorov, Olga A Mochalova, Stefanie M Ickert-Bond
The Kamchatka rhododendron (Therorhodion camtschaticum s.l.) is a small, cold-resistant arcto-alpine shrub species with a controversial taxonomy and a wide Beringian distribution, from northern Eurasia to Arctic North America. Some authors regard T. camtschaticum and the closely related Therorhodion glandulosum as separate species while others suggest that they represent regionally differentiated subspecies. In order to resolve this relationship, we sampled 33 populations within the native species ranges, using three fragments of plastid DNA (ptDNA) and ten nuclear microsatellites (nSSR). We recovered two genetic lineages consistent with species rather than subspecies. The distribution of these genetic lineages are consistent with two different migration pathways of species from western Beringia to eastern Beringia: (i) for T. glandulosum a northern pathway from northern East Asia to the Seward Peninsula in northern Alaska; and (ii) for T. camtschaticum a southern pathway from the southern part of western Beringia to the Aleutian Islands and the seashore of south-east Alaska. The northern route extends from the Okhotsk seashore through the Kolyma region, Chukotka, and central and northern Kamchatka. The southern route begins at the Sikhote-Alin ridge, and goes through Sakhalin Island, the Kuril Islands, and southern Kamchatka. Demographic analysis using nSSR data inferred a divergence time between T. camtschaticum and T. glandulosum long before the Last Glacial Maximum.
堪察加杜鹃花（Therorhodion camtschaticum s.l.）是一种小型、耐寒的极地高山灌木物种，其分类学颇有争议，在白令海地区分布广泛，从欧亚大陆北部一直到北美洲北极地区。一些作者认为 T. camtschaticum 和关系密切的 Therorhodion glandulosum 是两个独立的物种，而另一些作者则认为它们代表了地区差异亚种。为了解决这种关系，我们利用三个质体 DNA 片段（ptDNA）和十个核微卫星位点（nSSR）对原生种范围内的 33 个种群进行了采样。我们发现了两个与物种而非亚种一致的遗传系。这些基因系的分布与物种从白令西亚西部向白令西亚东部迁徙的两条不同路径一致：(i) T. glandulosum 从东亚北部向阿拉斯加北部的苏厄德半岛迁徙的北部路径；(ii) T. camtschaticum 从白令西亚西部南部向阿留申群岛和阿拉斯加东南部海滨迁徙的南部路径。北部路线从鄂霍次克海滨延伸到科雷马地区、楚科奇以及堪察加半岛中部和北部。南线始于锡霍特-阿林山脊，途经萨哈林岛、千岛群岛和堪察加半岛南部。利用 nSSR 数据进行的人口统计分析推断，T. camtschaticum 和 T. glandulosum 的分化时间早于末次冰川极盛时期。
{"title":"The migration history of the Kamchatka rhododendron (Therorhodion camtschaticum s.l.) indicates two distinct dispersal routes towards Eastern Beringia","authors":"Maria A Polezhaeva, Makar V Modorov, Olga A Mochalova, Stefanie M Ickert-Bond","doi":"10.1093/botlinnean/boae041","DOIUrl":"https://doi.org/10.1093/botlinnean/boae041","url":null,"abstract":"The Kamchatka rhododendron (Therorhodion camtschaticum s.l.) is a small, cold-resistant arcto-alpine shrub species with a controversial taxonomy and a wide Beringian distribution, from northern Eurasia to Arctic North America. Some authors regard T. camtschaticum and the closely related Therorhodion glandulosum as separate species while others suggest that they represent regionally differentiated subspecies. In order to resolve this relationship, we sampled 33 populations within the native species ranges, using three fragments of plastid DNA (ptDNA) and ten nuclear microsatellites (nSSR). We recovered two genetic lineages consistent with species rather than subspecies. The distribution of these genetic lineages are consistent with two different migration pathways of species from western Beringia to eastern Beringia: (i) for T. glandulosum a northern pathway from northern East Asia to the Seward Peninsula in northern Alaska; and (ii) for T. camtschaticum a southern pathway from the southern part of western Beringia to the Aleutian Islands and the seashore of south-east Alaska. The northern route extends from the Okhotsk seashore through the Kolyma region, Chukotka, and central and northern Kamchatka. The southern route begins at the Sikhote-Alin ridge, and goes through Sakhalin Island, the Kuril Islands, and southern Kamchatka. Demographic analysis using nSSR data inferred a divergence time between T. camtschaticum and T. glandulosum long before the Last Glacial Maximum.","PeriodicalId":9178,"journal":{"name":"Botanical Journal of the Linnean Society","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141968870","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-03DOI: 10.1093/botlinnean/boae052
Vladimir R Filin, Anna G Platonova
The tapetum is an important tissue in the sporangia of tracheophytes that provides nutrition for developing spores and participates in sporoderm construction, but the data on the tapetum in the sporangia of bryophytes and, in particular, hornworts, are contradictory. Some investigators considered the capsule wall and pseudoelates a tapetum in hornworts, but others suppose that the tapetum is absent in hornwort capsules at all. The structure of the sporocytes and spores, pseudoelaters, the lining layer of the capsule wall, and the outer layer of the columella of Phaeoceros laevis were studied at successive developmental stages by light, fluorescence, and transmission electron microscopy. We revealed that sporocytes accumulate carbohydrates that are required for the construction of the sporoderm and the storage of nutrients in mature spores before the formation of a special wall. Such a feature significantly distinguishes hornworts from mosses and angiosperms. Pseudoelaterocytes and pseudoelaters do not possess any ultrastructural features, indicating that they provide the sporocytes and spores with nutrition. Cells of the lining layer of the capsule wall and the outer layer of the columella do not possess characteristic ultrastructural features of secretory tissue at any developmental stage (in contrast to the moss tapetum), but they apparently participate in the transfer of nutrients in the capsule locule from the foot at the time the sporocytes are actively growing and accumulating nutrients. We accept the strict interpretation of the tapetum as a tissue that lines the capsule locule and has the specialized ultrastructure characteristic of the secretory tissues. Therefore, contrary to the opinion of some researchers, we believe that neither pseudoelaters nor the lining layer of the capsule wall should be considered a tapetum. Columella cells have a structural specialization for upward transport of assimilates, and they should not be regarded as a tapetum. We suppose that tapetum was absent in the common ancestor of the hornworts as well as in the common ancestor of embryophytes.
{"title":"Is there a tapetum in the hornwort capsule? Evidence from the sporogenesis of Phaeoceros","authors":"Vladimir R Filin, Anna G Platonova","doi":"10.1093/botlinnean/boae052","DOIUrl":"https://doi.org/10.1093/botlinnean/boae052","url":null,"abstract":"The tapetum is an important tissue in the sporangia of tracheophytes that provides nutrition for developing spores and participates in sporoderm construction, but the data on the tapetum in the sporangia of bryophytes and, in particular, hornworts, are contradictory. Some investigators considered the capsule wall and pseudoelates a tapetum in hornworts, but others suppose that the tapetum is absent in hornwort capsules at all. The structure of the sporocytes and spores, pseudoelaters, the lining layer of the capsule wall, and the outer layer of the columella of Phaeoceros laevis were studied at successive developmental stages by light, fluorescence, and transmission electron microscopy. We revealed that sporocytes accumulate carbohydrates that are required for the construction of the sporoderm and the storage of nutrients in mature spores before the formation of a special wall. Such a feature significantly distinguishes hornworts from mosses and angiosperms. Pseudoelaterocytes and pseudoelaters do not possess any ultrastructural features, indicating that they provide the sporocytes and spores with nutrition. Cells of the lining layer of the capsule wall and the outer layer of the columella do not possess characteristic ultrastructural features of secretory tissue at any developmental stage (in contrast to the moss tapetum), but they apparently participate in the transfer of nutrients in the capsule locule from the foot at the time the sporocytes are actively growing and accumulating nutrients. We accept the strict interpretation of the tapetum as a tissue that lines the capsule locule and has the specialized ultrastructure characteristic of the secretory tissues. Therefore, contrary to the opinion of some researchers, we believe that neither pseudoelaters nor the lining layer of the capsule wall should be considered a tapetum. Columella cells have a structural specialization for upward transport of assimilates, and they should not be regarded as a tapetum. We suppose that tapetum was absent in the common ancestor of the hornworts as well as in the common ancestor of embryophytes.","PeriodicalId":9178,"journal":{"name":"Botanical Journal of the Linnean Society","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141968868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-03DOI: 10.1093/botlinnean/boae044
Christian Silva, Júlia da Costa Hillmann, Juan Manuel Acosta, Reyjane Patrícia Oliveira, Fernando Omar Zuloaga
Panicum was once one of the largest grass genera with >450 species associated to >4000 names. The revelation of its polyphyletic nature emerged with the use of molecular data in phylogenetic studies. Consequently, most of its species have been transferred to other genera. A notable case occurred with Panicum (subg. Phanopyrum) sect. Stolonifera, whose species were recovered in tribe Paspaleae, distantly related to Panicum s.s. (P. subg. Panicum), placed in tribe Paniceae. Most species from the section were transferred to Ocellochloa, leaving only one enigmatic species, P. venezuelae, remaining as incertae sedis. In this study, we endeavoured to clarify the phylogenetic placement of P. venezuelae by expanding the taxon sampling and increasing the number of molecular markers. The nuclear External Transcribed Spacer marker was used for the first time in a comprehensive analysis of Paspalinae genera. Additionally, we reviewed the literature and herbarium records to provide a comprehensive update on the morphology and distribution of the species, and a conservation assessment. Our findings confirm that Panicum venezuelae belongs to the tribe Paspaleae, which is here transferred to a new genus, Drakkaria. However, identifying its closest relative remains an open question within Paspaleae. The new genus is considered here endemic to the diverse and threatened Neotropical Seasonally Dry Tropical Forests.
{"title":"One more step into the resolution of Panicum (Poaceae) polyphyly: Drakkaria, a new segregate genus from neotropical Seasonally Dry Tropical Forests","authors":"Christian Silva, Júlia da Costa Hillmann, Juan Manuel Acosta, Reyjane Patrícia Oliveira, Fernando Omar Zuloaga","doi":"10.1093/botlinnean/boae044","DOIUrl":"https://doi.org/10.1093/botlinnean/boae044","url":null,"abstract":"Panicum was once one of the largest grass genera with >450 species associated to >4000 names. The revelation of its polyphyletic nature emerged with the use of molecular data in phylogenetic studies. Consequently, most of its species have been transferred to other genera. A notable case occurred with Panicum (subg. Phanopyrum) sect. Stolonifera, whose species were recovered in tribe Paspaleae, distantly related to Panicum s.s. (P. subg. Panicum), placed in tribe Paniceae. Most species from the section were transferred to Ocellochloa, leaving only one enigmatic species, P. venezuelae, remaining as incertae sedis. In this study, we endeavoured to clarify the phylogenetic placement of P. venezuelae by expanding the taxon sampling and increasing the number of molecular markers. The nuclear External Transcribed Spacer marker was used for the first time in a comprehensive analysis of Paspalinae genera. Additionally, we reviewed the literature and herbarium records to provide a comprehensive update on the morphology and distribution of the species, and a conservation assessment. Our findings confirm that Panicum venezuelae belongs to the tribe Paspaleae, which is here transferred to a new genus, Drakkaria. However, identifying its closest relative remains an open question within Paspaleae. The new genus is considered here endemic to the diverse and threatened Neotropical Seasonally Dry Tropical Forests.","PeriodicalId":9178,"journal":{"name":"Botanical Journal of the Linnean Society","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141968869","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-01DOI: 10.1093/botlinnean/boae051
Florencia D Dosil Hiriart, Marcelo P Hernández, Luciano N Segura, Liliana Katinas
Myxodiaspory, the extrusion of sticky substances by the diaspores (seeds, fruits, anthocarps, and parts of infrutescences), has several selective advantages, one of which is aiding the adherence of diaspores between feathers/fur of animals that transport them over short or long distances. The diaspores of Asteraceae have three structures that can contain sticky substances: exocarp epidermal cells, exocarp trichomes, and viscid pappus. The South American species Adenostemma brasilianum (Asteraceae) has all three features. We examined the anatomy, secreted substances, and mode of adhesion of the diaspores of A. brasilianum to understand its strategies for dispersion. The fruit comprises an exocarp with glandular trichomes arranged spirally and scarce nonglandular trichomes, two layers of mesocarp separated by phytomelanin, and an endocarp. The pappus has a basal ring, a stalk, and a head with glandular trichomes. The mucilage, secreted by the glandular trichomes of fruit and pappus, reacted positively to tests for pectins, essential oils, lipophilic substances, and gums. The test for tannins gave a homogeneous positive reaction in the phytomelanin area, and as droplets, in the outer mesocarp layer and in the exocarp. The whole capitulum of A. brasilianum is adapted for successful transportation of its diaspores via diaspore release, secretion, and positioning. We discuss the idea that the dispersal adaptive traits found here evolved as phylogenetic parallelisms in the family.
{"title":"Myxodiaspory in Adenostemma brasilianum (Asteraceae): morphological and histochemical strategies for diaspore dispersion","authors":"Florencia D Dosil Hiriart, Marcelo P Hernández, Luciano N Segura, Liliana Katinas","doi":"10.1093/botlinnean/boae051","DOIUrl":"https://doi.org/10.1093/botlinnean/boae051","url":null,"abstract":"Myxodiaspory, the extrusion of sticky substances by the diaspores (seeds, fruits, anthocarps, and parts of infrutescences), has several selective advantages, one of which is aiding the adherence of diaspores between feathers/fur of animals that transport them over short or long distances. The diaspores of Asteraceae have three structures that can contain sticky substances: exocarp epidermal cells, exocarp trichomes, and viscid pappus. The South American species Adenostemma brasilianum (Asteraceae) has all three features. We examined the anatomy, secreted substances, and mode of adhesion of the diaspores of A. brasilianum to understand its strategies for dispersion. The fruit comprises an exocarp with glandular trichomes arranged spirally and scarce nonglandular trichomes, two layers of mesocarp separated by phytomelanin, and an endocarp. The pappus has a basal ring, a stalk, and a head with glandular trichomes. The mucilage, secreted by the glandular trichomes of fruit and pappus, reacted positively to tests for pectins, essential oils, lipophilic substances, and gums. The test for tannins gave a homogeneous positive reaction in the phytomelanin area, and as droplets, in the outer mesocarp layer and in the exocarp. The whole capitulum of A. brasilianum is adapted for successful transportation of its diaspores via diaspore release, secretion, and positioning. We discuss the idea that the dispersal adaptive traits found here evolved as phylogenetic parallelisms in the family.","PeriodicalId":9178,"journal":{"name":"Botanical Journal of the Linnean Society","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141880905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-22DOI: 10.1093/botlinnean/boae027
Lucas Vieira Lima, Thaís Elias Almeida, Michael Kessler, Germinal Rouhan, Shuichiro Tagane, Vinícius Antonio de Oliveira Dittrich, Alexandre Salino
Gleicheniaceae is an early diverging lineage of leptosporangiate ferns. Although the family can be readily recognized by the pseudodichotomous branching pattern of its fronds, generic circumscription has long been debated. Phylogenetic analyses based on genomic data supported the monophyly of six genera (Dicranopteris, Diplopterygium, Gleichenella, Gleichenia, Rouxopteris, and Stromatopteris) but indicate the paraphyly of Sticherus. To accommodate this latter result, we describe a new genus, Sticheropsis, gen. nov., segregated from Sticherus. We provide a new taxonomic treatment of Gleicheniaceae, including an identification key to all eight genera, descriptions of the genera with comments and notes concerning geographic distributions and phylogenetic affinities, as well as an overview of the morphology of the family with a revised and unified terminology for the fronds. We recognize 149 species plus two hybrids for the family, distributed into eight genera, and propose six new combinations.
{"title":"The classification of the fern family Gleicheniaceae, with the description of a new genus, segregated from Sticherus","authors":"Lucas Vieira Lima, Thaís Elias Almeida, Michael Kessler, Germinal Rouhan, Shuichiro Tagane, Vinícius Antonio de Oliveira Dittrich, Alexandre Salino","doi":"10.1093/botlinnean/boae027","DOIUrl":"https://doi.org/10.1093/botlinnean/boae027","url":null,"abstract":"Gleicheniaceae is an early diverging lineage of leptosporangiate ferns. Although the family can be readily recognized by the pseudodichotomous branching pattern of its fronds, generic circumscription has long been debated. Phylogenetic analyses based on genomic data supported the monophyly of six genera (Dicranopteris, Diplopterygium, Gleichenella, Gleichenia, Rouxopteris, and Stromatopteris) but indicate the paraphyly of Sticherus. To accommodate this latter result, we describe a new genus, Sticheropsis, gen. nov., segregated from Sticherus. We provide a new taxonomic treatment of Gleicheniaceae, including an identification key to all eight genera, descriptions of the genera with comments and notes concerning geographic distributions and phylogenetic affinities, as well as an overview of the morphology of the family with a revised and unified terminology for the fronds. We recognize 149 species plus two hybrids for the family, distributed into eight genera, and propose six new combinations.","PeriodicalId":9178,"journal":{"name":"Botanical Journal of the Linnean Society","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141776193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-20DOI: 10.1093/botlinnean/boae046
Olga V Yatsenko, Alexey N Sorokin, Mikhail S Romanov, Alexey V F Ch Bobrov, Petr S Iovlev, Nikita S Zdravchev, Anton S Timchenko, Anna A Mikhaylova, Natalia D Vasekha, Maxim V Kandidov, Kirill V Kuptsov
Details of fruit anatomy and pericarp histogenesis were studied in Mediterranean species of Arbutus with the aim to determine the morphogenetic fruit type, to reveal the functional and ecological significance of fruit structure, and to suggest the most probable scenarios of fruit structural transformations in Arbutoideae (Ericaceae). The pericarp of the coenocarpous berries of Arbutus is differentiated into: one-layered exocarp, multilayered parenchymatous mesocarp with scattered solitary and groups of sclereids, and one-layered endocarp composed of thin-walled cells. The warts covering the fruit surface are formed by parenchymatous cells of the mesocarp and the exocarp. The process of pericarp development in Arbutus is divided into four periods, which correlate with the phenology and climatic factors of the Mediterranean region. The origin of the dormancy period in the middle part of fruit development in Arbutus is interpreted as an important adaptation to the arid Mediterranean climate. The data obtained suggest that both the berry of Arbutus and the pyrenariums of Arctostaphylos and Arctous are highly specialized fruit types that could not have derived from each other. The capsule of Hamamelis type of Enkianthoideae is recognized as the original fruit type of the berries and pyrenariums of Arbutoideae.
{"title":"Fruit anatomy and histogenesis in Mediterranean species of Arbutus (Ericaceae: Arbutoideae): ecological and morphogenetic aspects","authors":"Olga V Yatsenko, Alexey N Sorokin, Mikhail S Romanov, Alexey V F Ch Bobrov, Petr S Iovlev, Nikita S Zdravchev, Anton S Timchenko, Anna A Mikhaylova, Natalia D Vasekha, Maxim V Kandidov, Kirill V Kuptsov","doi":"10.1093/botlinnean/boae046","DOIUrl":"https://doi.org/10.1093/botlinnean/boae046","url":null,"abstract":"Details of fruit anatomy and pericarp histogenesis were studied in Mediterranean species of Arbutus with the aim to determine the morphogenetic fruit type, to reveal the functional and ecological significance of fruit structure, and to suggest the most probable scenarios of fruit structural transformations in Arbutoideae (Ericaceae). The pericarp of the coenocarpous berries of Arbutus is differentiated into: one-layered exocarp, multilayered parenchymatous mesocarp with scattered solitary and groups of sclereids, and one-layered endocarp composed of thin-walled cells. The warts covering the fruit surface are formed by parenchymatous cells of the mesocarp and the exocarp. The process of pericarp development in Arbutus is divided into four periods, which correlate with the phenology and climatic factors of the Mediterranean region. The origin of the dormancy period in the middle part of fruit development in Arbutus is interpreted as an important adaptation to the arid Mediterranean climate. The data obtained suggest that both the berry of Arbutus and the pyrenariums of Arctostaphylos and Arctous are highly specialized fruit types that could not have derived from each other. The capsule of Hamamelis type of Enkianthoideae is recognized as the original fruit type of the berries and pyrenariums of Arbutoideae.","PeriodicalId":9178,"journal":{"name":"Botanical Journal of the Linnean Society","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141743657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-13DOI: 10.1093/botlinnean/boae040
Katrijn De Bock, Hans Jacquemyn, Nhora H Ospina-Calderón, Nicola S Flanagan, Agustina Ventre-Lespiaucq
Assessing variation in root functional traits may offer novel insights into plant adaptations to changing environmental conditions. However, such studies, particularly on epiphytic species in tropical ecosystems, are still limited. Previous research has suggested that precipitation has a major impact on epiphyte survival and thus can be considered a candidate driver of epiphytic root trait variation, though compelling evidence is lacking. In this study, we investigated variation in 19 root functional traits in 43 epiphytic (36 species) and 14 terrestrial (7 species) orchids along an elevational gradient in Colombia and examined whether this variation is associated with differences in abiotic conditions. Contrary to previous studies, our findings did not associate trait variation with precipitation but revealed strong correlations with solar radiation, temperature, and water vapour pressure. The variation was particularly pronounced in traits related to the velamen radicum. Epiphytic and terrestrial orchids showed similar responses despite their different growth habits. Overall, these patterns suggest that higher sunlight and temperature conditions lead both orchid types to allocate more resources to root structures that mitigate abiotic stress, and highlight the role of other environmental factors in driving root trait variability.
{"title":"Variation in root functional traits of Neotropical epiphytic and terrestrial orchids along an elevational gradient","authors":"Katrijn De Bock, Hans Jacquemyn, Nhora H Ospina-Calderón, Nicola S Flanagan, Agustina Ventre-Lespiaucq","doi":"10.1093/botlinnean/boae040","DOIUrl":"https://doi.org/10.1093/botlinnean/boae040","url":null,"abstract":"Assessing variation in root functional traits may offer novel insights into plant adaptations to changing environmental conditions. However, such studies, particularly on epiphytic species in tropical ecosystems, are still limited. Previous research has suggested that precipitation has a major impact on epiphyte survival and thus can be considered a candidate driver of epiphytic root trait variation, though compelling evidence is lacking. In this study, we investigated variation in 19 root functional traits in 43 epiphytic (36 species) and 14 terrestrial (7 species) orchids along an elevational gradient in Colombia and examined whether this variation is associated with differences in abiotic conditions. Contrary to previous studies, our findings did not associate trait variation with precipitation but revealed strong correlations with solar radiation, temperature, and water vapour pressure. The variation was particularly pronounced in traits related to the velamen radicum. Epiphytic and terrestrial orchids showed similar responses despite their different growth habits. Overall, these patterns suggest that higher sunlight and temperature conditions lead both orchid types to allocate more resources to root structures that mitigate abiotic stress, and highlight the role of other environmental factors in driving root trait variability.","PeriodicalId":9178,"journal":{"name":"Botanical Journal of the Linnean Society","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141611532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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