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Léanne L. Dreyer - One of the best experts on this subject based on the ideXlab platform.
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Nomenclatural notes on southern African Oxalis species
Bothalia, 2018Co-Authors: Léanne L. Dreyer, Kenneth C. Oberlander, Ronell R. KlopperAbstract:Background: The correct author citation of Oxalis sonderiana (Kuntze) J.F.Macbr. and the validity and identity of the species Oxalis beneprotecta R.Knuth, Oxalis bullulata T.M.Salter and Oxalis pulchella Jacq. var. beneprotecta (R.Knuth) T.M.Salter are unclear. Objectives: To resolve the nomenclatural and taxonomic confusion surrounding these four taxa. Method: We studied relevant herbarium records (especially type material) of all the taxa, and paired this with scrutiny of all publications that bear reference to the nomenclature and taxonomy of these species. Results: The correct author citation for Oxalis sonderiana has been determined; Oxalis bullulata is confirmed as a distinct species, and the continued recognition of Oxalis beneprotecta as a variety of Oxalis pulchella is suggested. It is further ascertained that the name ‘ Oxalis nidulans Turcz.’ is not a later homonym, but a reference to a misapplication of Oxalis nidulans Eckl. & Zeyh. to the type specimen of Oxalis sonderiana . Conclusion: These results clarify the current confusion surrounding these taxa in global herbaria and in national and international databases.
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Two new Oxalis (Oxalidaceae) species, including 5 varieties, from the Richtersveld of South Africa
Phytotaxa, 2017Co-Authors: Léanne L. Dreyer, Francois Roets, Kenneth C. OberlanderAbstract:Two new species of Oxalis (Oxalidaceae) from the Richtersveld are described, namely Oxalis canaliculata and O. magnifolia . These widespread species are morphologically distinct and easily identified, but both contain populations in which individuals consistently differ morphologically from typical varieties. The typical variety of Oxalis canaliculata is widespread throughout the Richtersveld, while O. canaliculata var. trifoliolata is known from a single population and O. canaliculata var. graniticola is known only from granite outcrops. Oxalis magnifolia includes the typical variety that is widespread and Oxalis magnifolia var. reduplicata , which is only known from two populations in close proximity to one another. Morphological characters, preliminary phylogenetic position based on data from the nuclear ITS region, habitat description and formal taxonomic descriptions are provided for all taxa. The diagnostic characters of the new species are compared to all phenotypically similar southern African species.
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The phylogenetic significance of leaf anatomical traits of southern African Oxalis.
BMC evolutionary biology, 2016Co-Authors: Michelle Jooste, Léanne L. Dreyer, Kenneth C. OberlanderAbstract:Background The southern African Oxalis radiation is extremely morphologically variable. Despite recent progress in the phylogenetics of the genus, there are few morphological synapomorphies supporting DNA-based clades. Leaflet anatomy can provide an understudied and potentially valuable source of information on the evolutionary history and systematics of this lineage. Fifty-nine leaflet anatomical traits of 109 southern African Oxalis species were assessed in search of phylogenetically significant characters that delineate clades.
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New relatives of Oxalis pes-caprae (Oxalidaceae) from South Africa
Blumea - Biodiversity Evolution and Biogeography of Plants, 2014Co-Authors: Francois Roets, Kenneth C. Oberlander, Léanne L. DreyerAbstract:The genus Oxalis in southern Africa contains more than 200 species, with the vast bulk of species in the Greater Cape Floristic Region (GCFR). Recent fieldwork has suggested that many await discovery. Here we investigate the identity of two apparently undescribed Oxalis species from Northern Cape, South Africa, using morphological comparisons with closely related taxa. We provide a preliminary phylogenetic placement using DNA sequence-based analyses of the Internal Transcribed Spacer (ITS) region. Both putative new species are distinguished from all known Oxalis species based on macro-morphological traits. Molecular data placed both within a clade consisting of the weedy O. pes-caprae and its close relatives. Oxalis hirsutibulba sp. nov. is characterised by densely hairy bulb tunics, a trait absent from all known members of the O. pes-caprae clade. Oxalis fenestrata sp. nov. is unique in producing apple green succulent stems and leaflets usually with translucent white markings at their incisions. We also provide the first phylogenetic placement of the GCFR narrow endemic O. lasiorrhiza in the O. pes-caprae clade. In conjunction with several other recent discoveries, these two new species and the phylogenetic placement of O. lasiorrhiza show that the O. pes-caprae clade is much more speciose than previously estimated.
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An Unusual Night-Flowering Oxalis from South Africa (Oxalidaceae)
Systematic Botany, 2014Co-Authors: Léanne L. Dreyer, R. M. Macfarlane, Francois Roets, Kenneth C. OberlanderAbstract:Abstract A new Oxalis (Oxalidaceae) species from the Hantamsberg (South Africa) is described and typified as Oxalis noctiflora using morphological, palynological, and molecular characters. Superficially it closely resembles Oxalis aridicola, Oxalis callosa, Oxalis odorata, and Oxalis primuloides, and it shares a unique supra-areolate pollen type with most of these species. No single vegetative morphological character defines this species, but a unique combination of bulb and leaflet characters distinguishes it from all other known species. The flowers of Oxalis noctiflora are unique for the genus in displaying typical moth-pollination characters. The white flowers open at night, have a long, unusually narrow, corolla tube, and produce a strong sweet scent. All previously described Oxalis species have flowers that open during the day. Phylogenetic analyses based on nuclear Internal Transcribed Spacer data placed this species sister to O. aridicola within a clade of morphologically and palynologically simil...
Kenneth C. Oberlander - One of the best experts on this subject based on the ideXlab platform.
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Nomenclatural notes on southern African Oxalis species
Bothalia, 2018Co-Authors: Léanne L. Dreyer, Kenneth C. Oberlander, Ronell R. KlopperAbstract:Background: The correct author citation of Oxalis sonderiana (Kuntze) J.F.Macbr. and the validity and identity of the species Oxalis beneprotecta R.Knuth, Oxalis bullulata T.M.Salter and Oxalis pulchella Jacq. var. beneprotecta (R.Knuth) T.M.Salter are unclear. Objectives: To resolve the nomenclatural and taxonomic confusion surrounding these four taxa. Method: We studied relevant herbarium records (especially type material) of all the taxa, and paired this with scrutiny of all publications that bear reference to the nomenclature and taxonomy of these species. Results: The correct author citation for Oxalis sonderiana has been determined; Oxalis bullulata is confirmed as a distinct species, and the continued recognition of Oxalis beneprotecta as a variety of Oxalis pulchella is suggested. It is further ascertained that the name ‘ Oxalis nidulans Turcz.’ is not a later homonym, but a reference to a misapplication of Oxalis nidulans Eckl. & Zeyh. to the type specimen of Oxalis sonderiana . Conclusion: These results clarify the current confusion surrounding these taxa in global herbaria and in national and international databases.
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Two new Oxalis (Oxalidaceae) species, including 5 varieties, from the Richtersveld of South Africa
Phytotaxa, 2017Co-Authors: Léanne L. Dreyer, Francois Roets, Kenneth C. OberlanderAbstract:Two new species of Oxalis (Oxalidaceae) from the Richtersveld are described, namely Oxalis canaliculata and O. magnifolia . These widespread species are morphologically distinct and easily identified, but both contain populations in which individuals consistently differ morphologically from typical varieties. The typical variety of Oxalis canaliculata is widespread throughout the Richtersveld, while O. canaliculata var. trifoliolata is known from a single population and O. canaliculata var. graniticola is known only from granite outcrops. Oxalis magnifolia includes the typical variety that is widespread and Oxalis magnifolia var. reduplicata , which is only known from two populations in close proximity to one another. Morphological characters, preliminary phylogenetic position based on data from the nuclear ITS region, habitat description and formal taxonomic descriptions are provided for all taxa. The diagnostic characters of the new species are compared to all phenotypically similar southern African species.
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Oxalis dreyerae (Oxalidaceae), a new species from South Africa
Phytotaxa, 2016Co-Authors: Francois Roets, Kenneth C. OberlanderAbstract:Oxalis dreyerae , a new species from the arid Richtersveld region of South Africa, is described. It is most similar to O. inconspicua from which it differs, among others, by having a larger plant body, larger and showier flowers with a broadly trumpet-shaped tube, much larger leaflets, petioles that are thicker than the peduncles, much larger lanceolate sepals and short, stubby teeth on the longer filaments. Its placement within the O. flava clade is supported by nrDNA ITS sequence evidence, which is also consistent with a close relationship to O. inconspicua. Oxalis dreyerae represents the eighth described species of Oxalis endemic to the arid Richtersveld of the Northern Cape, thus supporting the importance of the floristically diverse Gariep Centre of Endemism, of which the region forms a part.
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The phylogenetic significance of leaf anatomical traits of southern African Oxalis.
BMC evolutionary biology, 2016Co-Authors: Michelle Jooste, Léanne L. Dreyer, Kenneth C. OberlanderAbstract:Background The southern African Oxalis radiation is extremely morphologically variable. Despite recent progress in the phylogenetics of the genus, there are few morphological synapomorphies supporting DNA-based clades. Leaflet anatomy can provide an understudied and potentially valuable source of information on the evolutionary history and systematics of this lineage. Fifty-nine leaflet anatomical traits of 109 southern African Oxalis species were assessed in search of phylogenetically significant characters that delineate clades.
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New relatives of Oxalis pes-caprae (Oxalidaceae) from South Africa
Blumea - Biodiversity Evolution and Biogeography of Plants, 2014Co-Authors: Francois Roets, Kenneth C. Oberlander, Léanne L. DreyerAbstract:The genus Oxalis in southern Africa contains more than 200 species, with the vast bulk of species in the Greater Cape Floristic Region (GCFR). Recent fieldwork has suggested that many await discovery. Here we investigate the identity of two apparently undescribed Oxalis species from Northern Cape, South Africa, using morphological comparisons with closely related taxa. We provide a preliminary phylogenetic placement using DNA sequence-based analyses of the Internal Transcribed Spacer (ITS) region. Both putative new species are distinguished from all known Oxalis species based on macro-morphological traits. Molecular data placed both within a clade consisting of the weedy O. pes-caprae and its close relatives. Oxalis hirsutibulba sp. nov. is characterised by densely hairy bulb tunics, a trait absent from all known members of the O. pes-caprae clade. Oxalis fenestrata sp. nov. is unique in producing apple green succulent stems and leaflets usually with translucent white markings at their incisions. We also provide the first phylogenetic placement of the GCFR narrow endemic O. lasiorrhiza in the O. pes-caprae clade. In conjunction with several other recent discoveries, these two new species and the phylogenetic placement of O. lasiorrhiza show that the O. pes-caprae clade is much more speciose than previously estimated.
Eve Emshwiller - One of the best experts on this subject based on the ideXlab platform.
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diversification of the american bulb bearing Oxalis oxalidaceae dispersal to north america and modification of the tristylous breeding system
American Journal of Botany, 2012Co-Authors: Andrew G Gardner, Magdalena Vaio, Marcelo Guerra, Eve EmshwillerAbstract:PREMISE OF THE STUDY The American bulb-bearing Oxalis (Oxalidaceae) have diverse heterostylous breeding systems and are distributed in mountainous areas from Patagonia to the northeastern United States. To study the evolutionary processes leading to this diversity, we constructed the first molecular phylogeny for the American bulb-bearing Oxalis and used it to infer biogeographic history and breeding system evolution. METHODS We used DNA sequence data (nuclear ribosomal internal transcribed spacer, trnL-trnL-trnF, trnT-trnL, and psbJ-petA) to infer phylogenetic history via parsimony, likelihood, and Bayesian analyses. We used Bayes Multistate to infer ancestral geographic distributions at well-supported nodes of the phylogeny. The Shimodaira-Hasegawa (SH) test distinguished among hypotheses of single or multiple transitions from South America to North America, and tristyly to distyly. KEY RESULTS The American bulb-bearing Oxalis include sampled members of sections IonOxalis and Pseudobulbosae and are derived from a larger clade that includes members of sections Palmatifoliae, Articulatae, and the African species. The American bulb-bearing Oxalis comprise two clades: one distributed in SE South America and the other in the Andes and North America. An SH test supports multiple dispersals to North America. Most sampled distylous species form a single clade, but at least two other independent distylous lineages are supported by the topologies and SH tests. CONCLUSIONS Phylogenetic results suggest the American bulb-bearing Oxalis originated in southern South America, dispersed repeatedly to North America, and had multiple transitions from tristyly to distyly. This study adds to our understanding of biogeographic history and breeding system evolution and provides a foundation for more precise inferences about the study group.
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The Role of Organic Acids in the Domestication of Oxalis tuberosa: A New Model for Studying Domestication Resulting in Opposing Crop Phenotypes^1
Economic Botany, 2011Co-Authors: E. Jane Bradbury, Eve EmshwillerAbstract:Los ácidos orgánicos y la domesticación de Oxalis tuberosa: un nuevo modelo para el estudio de la domesticación que resulta en los fenotipos domésticos opuestos. Aunque pocos cultivos presentan fenotipos domésticos directamente opuestos , estos cultivos pueden ser la clave para entender los procesos de domesticación que muestran conflicto en la presión selectiva en el ecosistema agrícola. Dos ejemplos relativamente bien conocidos son la yuca (Manihot esculenta Crantz), que tiene variedades de alto y bajo contenido de cianuro, y la papa (Solanum sección Petota). Entre las papas hay varias especies, incluyendo la papa común (Solanum tuberosum L.), que tienen bajos niveles de glicoalcaloides mientras otras especies como las "papas amargas", tienen elevados niveles de glicoalcaloides. Nosotros proponemos que Oxalis tuberosa Molina, oca, puede representar un tercer ejemplo de este sistema de cultivo, con niveles altos y bajos de ácidos orgánicos. Cada grupo de variedades de oca tiene diferentes practicas culturales respecto a su preparación como alimentos (categorías de uso), similar a las categorías de uso que se han descrito para las papas en los Andes (Brush et al. Economic Botany 35;70–88, 1981 ; Zimmerer Journal of Biogeography 18;165–178, 1991 ). Los análisis iniciales sugieren que los ácidos orgánicos en los tubérculos pueden deberse a una diferencia bioquímica importante entre el uso de categorías basadas en el ácido oxálico y los datos de pH. En este artículo examinamos nuestra interpretación de los ácidos orgánicos en los tubérculos de oca, además de destacar las áreas que merecen mayor investigación. The Role of Organic Acids in the Domestication of Oxalis tuberosa : A New Model for Studying Domestication Resulting in Opposing Crop Phenotypes. Though few crops display directly opposing domesticated phenotypes, these crops may be the key to understanding domestication processes that address conflicting selective pressures in the agricultural ecosystem. Two relatively well-known examples are cassava ( Manihot esculenta Crantz), which has high-cyanide and low-cyanide varieties, and potato ( Solanum section Petota ). Among the potatoes are several species, including the common potato ( Solanum tuberosum L.), that have low levels of glycoalkaloids and there are other species of “bitter potato” with elevated levels of glycoalkaloids. We propose that Oxalis tuberosa Molina, “oca,” may represent a third example of such a crop system, with opposing high organic acid and low organic acid cultivars. Each cultivar set has different cultural food preparation practices (“use-categories”), similar to the “use-categories” that have been described for potatoes in the Andes (Brush et al. Economic Botany 35;70–88, 1981 ; Zimmerer Journal of Biogeography 18;165–178, 1991 ). Our initial analyses suggest that organic acids in tubers may be an important biochemical difference between use-categories, based on both oxalic acid and pH data. Here, we review our understanding of organic acids in oca tubers, while highlighting areas that merit further investigation.
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the role of organic acids in the domestication of Oxalis tuberosa a new model for studying domestication resulting in opposing crop phenotypes1
Economic Botany, 2011Co-Authors: Jane E Bradbury, Eve EmshwillerAbstract:The Role of Organic Acids in the Domestication ofOxalis tuberosa: A New Model for Studying Domestication Resulting in Opposing Crop Phenotypes. Though few crops display directly opposing domesticated phenotypes, these crops may be the key to understanding domestication processes that address conflicting selective pressures in the agricultural ecosystem. Two relatively well-known examples are cassava (Manihot esculenta Crantz), which has high-cyanide and low-cyanide varieties, and potato (Solanum section Petota). Among the potatoes are several species, including the common potato (Solanum tuberosum L.), that have low levels of glycoalkaloids and there are other species of “bitter potato” with elevated levels of glycoalkaloids. We propose that Oxalis tuberosa Molina, “oca,” may represent a third example of such a crop system, with opposing high organic acid and low organic acid cultivars. Each cultivar set has different cultural food preparation practices (“use-categories”), similar to the “use-categories” that have been described for potatoes in the Andes (Brush et al. Economic Botany 35;70–88, 1981; Zimmerer Journal of Biogeography 18;165–178, 1991). Our initial analyses suggest that organic acids in tubers may be an important biochemical difference between use-categories, based on both oxalic acid and pH data. Here, we review our understanding of organic acids in oca tubers, while highlighting areas that merit further investigation.
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origins of domestication and polyploidy in oca Oxalis tuberosa oxalidaceae 3 aflp data of oca and four wild tuber bearing taxa
American Journal of Botany, 2009Co-Authors: Eve Emshwiller, Terra J. Theim, Alfredo Grau, Victor Nina, Franz TerrazasAbstract:Many crops are polyploids, and it can be challenging to untangle the often complicated history of their origins of domestication and origins of polyploidy. To complement other studies of the origins of polyploidy of the octoploid tuber crop oca (Oxalis tube rosa) that used DNA sequence data and phylogenetic methods, we here compared AFLP data for oca with four wild, tuber-bearing Oxalis taxa found in different regions of the central Andes. Results confirmed the divergence of two use-categories of cultivated oca that indigenous farmers use for different purposes, suggesting the possibility that they might have had separate origins of do mestication. Despite previous results with nuclear-encoded, chloroplast-expressed glutamine synthetase suggesting that O. pic chensis might be a progenitor of oca, AFLP data of this species, as well as different populations of wild, tuber-bearing Oxalis found in Lima Department, Peru, were relatively divergent from O. tuberosa. Results from all analytical methods suggested that the unnamed wild, tuber-bearing Oxalis found in Bolivia and O. chicligastensis in NW Argentina are the best candidates as the genome donors for polyploid O. tuberosa, but the results were somewhat equivocal about which of these two taxa is the more strongly supported as oca's progenitor.
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Origins of domestication and polyploidy in oca (Oxalis tuberosa; Oxalidaceae). 3. AFLP data of oca and four wild, tuber‐bearing taxa
American Journal of Botany, 2009Co-Authors: Eve Emshwiller, Terra J. Theim, Alfredo Grau, Victor Nina, Franz TerrazasAbstract:Many crops are polyploids, and it can be challenging to untangle the often complicated history of their origins of domestication and origins of polyploidy. To complement other studies of the origins of polyploidy of the octoploid tuber crop oca (Oxalis tube rosa) that used DNA sequence data and phylogenetic methods, we here compared AFLP data for oca with four wild, tuber-bearing Oxalis taxa found in different regions of the central Andes. Results confirmed the divergence of two use-categories of cultivated oca that indigenous farmers use for different purposes, suggesting the possibility that they might have had separate origins of do mestication. Despite previous results with nuclear-encoded, chloroplast-expressed glutamine synthetase suggesting that O. pic chensis might be a progenitor of oca, AFLP data of this species, as well as different populations of wild, tuber-bearing Oxalis found in Lima Department, Peru, were relatively divergent from O. tuberosa. Results from all analytical methods suggested that the unnamed wild, tuber-bearing Oxalis found in Bolivia and O. chicligastensis in NW Argentina are the best candidates as the genome donors for polyploid O. tuberosa, but the results were somewhat equivocal about which of these two taxa is the more strongly supported as oca's progenitor.
Franz Terrazas - One of the best experts on this subject based on the ideXlab platform.
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origins of domestication and polyploidy in oca Oxalis tuberosa oxalidaceae 3 aflp data of oca and four wild tuber bearing taxa
American Journal of Botany, 2009Co-Authors: Eve Emshwiller, Terra J. Theim, Alfredo Grau, Victor Nina, Franz TerrazasAbstract:Many crops are polyploids, and it can be challenging to untangle the often complicated history of their origins of domestication and origins of polyploidy. To complement other studies of the origins of polyploidy of the octoploid tuber crop oca (Oxalis tube rosa) that used DNA sequence data and phylogenetic methods, we here compared AFLP data for oca with four wild, tuber-bearing Oxalis taxa found in different regions of the central Andes. Results confirmed the divergence of two use-categories of cultivated oca that indigenous farmers use for different purposes, suggesting the possibility that they might have had separate origins of do mestication. Despite previous results with nuclear-encoded, chloroplast-expressed glutamine synthetase suggesting that O. pic chensis might be a progenitor of oca, AFLP data of this species, as well as different populations of wild, tuber-bearing Oxalis found in Lima Department, Peru, were relatively divergent from O. tuberosa. Results from all analytical methods suggested that the unnamed wild, tuber-bearing Oxalis found in Bolivia and O. chicligastensis in NW Argentina are the best candidates as the genome donors for polyploid O. tuberosa, but the results were somewhat equivocal about which of these two taxa is the more strongly supported as oca's progenitor.
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Origins of domestication and polyploidy in oca (Oxalis tuberosa; Oxalidaceae). 3. AFLP data of oca and four wild, tuber‐bearing taxa
American Journal of Botany, 2009Co-Authors: Eve Emshwiller, Terra J. Theim, Alfredo Grau, Victor Nina, Franz TerrazasAbstract:Many crops are polyploids, and it can be challenging to untangle the often complicated history of their origins of domestication and origins of polyploidy. To complement other studies of the origins of polyploidy of the octoploid tuber crop oca (Oxalis tube rosa) that used DNA sequence data and phylogenetic methods, we here compared AFLP data for oca with four wild, tuber-bearing Oxalis taxa found in different regions of the central Andes. Results confirmed the divergence of two use-categories of cultivated oca that indigenous farmers use for different purposes, suggesting the possibility that they might have had separate origins of do mestication. Despite previous results with nuclear-encoded, chloroplast-expressed glutamine synthetase suggesting that O. pic chensis might be a progenitor of oca, AFLP data of this species, as well as different populations of wild, tuber-bearing Oxalis found in Lima Department, Peru, were relatively divergent from O. tuberosa. Results from all analytical methods suggested that the unnamed wild, tuber-bearing Oxalis found in Bolivia and O. chicligastensis in NW Argentina are the best candidates as the genome donors for polyploid O. tuberosa, but the results were somewhat equivocal about which of these two taxa is the more strongly supported as oca's progenitor.
Francois Roets - One of the best experts on this subject based on the ideXlab platform.
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Two new Oxalis (Oxalidaceae) species, including 5 varieties, from the Richtersveld of South Africa
Phytotaxa, 2017Co-Authors: Léanne L. Dreyer, Francois Roets, Kenneth C. OberlanderAbstract:Two new species of Oxalis (Oxalidaceae) from the Richtersveld are described, namely Oxalis canaliculata and O. magnifolia . These widespread species are morphologically distinct and easily identified, but both contain populations in which individuals consistently differ morphologically from typical varieties. The typical variety of Oxalis canaliculata is widespread throughout the Richtersveld, while O. canaliculata var. trifoliolata is known from a single population and O. canaliculata var. graniticola is known only from granite outcrops. Oxalis magnifolia includes the typical variety that is widespread and Oxalis magnifolia var. reduplicata , which is only known from two populations in close proximity to one another. Morphological characters, preliminary phylogenetic position based on data from the nuclear ITS region, habitat description and formal taxonomic descriptions are provided for all taxa. The diagnostic characters of the new species are compared to all phenotypically similar southern African species.
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Oxalis dreyerae (Oxalidaceae), a new species from South Africa
Phytotaxa, 2016Co-Authors: Francois Roets, Kenneth C. OberlanderAbstract:Oxalis dreyerae , a new species from the arid Richtersveld region of South Africa, is described. It is most similar to O. inconspicua from which it differs, among others, by having a larger plant body, larger and showier flowers with a broadly trumpet-shaped tube, much larger leaflets, petioles that are thicker than the peduncles, much larger lanceolate sepals and short, stubby teeth on the longer filaments. Its placement within the O. flava clade is supported by nrDNA ITS sequence evidence, which is also consistent with a close relationship to O. inconspicua. Oxalis dreyerae represents the eighth described species of Oxalis endemic to the arid Richtersveld of the Northern Cape, thus supporting the importance of the floristically diverse Gariep Centre of Endemism, of which the region forms a part.
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New relatives of Oxalis pes-caprae (Oxalidaceae) from South Africa
Blumea - Biodiversity Evolution and Biogeography of Plants, 2014Co-Authors: Francois Roets, Kenneth C. Oberlander, Léanne L. DreyerAbstract:The genus Oxalis in southern Africa contains more than 200 species, with the vast bulk of species in the Greater Cape Floristic Region (GCFR). Recent fieldwork has suggested that many await discovery. Here we investigate the identity of two apparently undescribed Oxalis species from Northern Cape, South Africa, using morphological comparisons with closely related taxa. We provide a preliminary phylogenetic placement using DNA sequence-based analyses of the Internal Transcribed Spacer (ITS) region. Both putative new species are distinguished from all known Oxalis species based on macro-morphological traits. Molecular data placed both within a clade consisting of the weedy O. pes-caprae and its close relatives. Oxalis hirsutibulba sp. nov. is characterised by densely hairy bulb tunics, a trait absent from all known members of the O. pes-caprae clade. Oxalis fenestrata sp. nov. is unique in producing apple green succulent stems and leaflets usually with translucent white markings at their incisions. We also provide the first phylogenetic placement of the GCFR narrow endemic O. lasiorrhiza in the O. pes-caprae clade. In conjunction with several other recent discoveries, these two new species and the phylogenetic placement of O. lasiorrhiza show that the O. pes-caprae clade is much more speciose than previously estimated.
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An Unusual Night-Flowering Oxalis from South Africa (Oxalidaceae)
Systematic Botany, 2014Co-Authors: Léanne L. Dreyer, R. M. Macfarlane, Francois Roets, Kenneth C. OberlanderAbstract:Abstract A new Oxalis (Oxalidaceae) species from the Hantamsberg (South Africa) is described and typified as Oxalis noctiflora using morphological, palynological, and molecular characters. Superficially it closely resembles Oxalis aridicola, Oxalis callosa, Oxalis odorata, and Oxalis primuloides, and it shares a unique supra-areolate pollen type with most of these species. No single vegetative morphological character defines this species, but a unique combination of bulb and leaflet characters distinguishes it from all other known species. The flowers of Oxalis noctiflora are unique for the genus in displaying typical moth-pollination characters. The white flowers open at night, have a long, unusually narrow, corolla tube, and produce a strong sweet scent. All previously described Oxalis species have flowers that open during the day. Phylogenetic analyses based on nuclear Internal Transcribed Spacer data placed this species sister to O. aridicola within a clade of morphologically and palynologically simil...
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Discovery of substantial Oxalis (Oxalidaceae) diversity and endemism in an arid biodiversity hotspot
Phytotaxa, 2014Co-Authors: Kenneth C. Oberlander, Francois Roets, Léanne L. DreyerAbstract:Despite globally acknowledged diversity levels, the flora of the arid Richtersveld of South Africa remains poorly known for certain plant lineages, including the eudicot genus Oxalis . Cryptic habit, inaccessible and harsh terrain and the lack of focussed systematic attention has led to the assumption that the region is depauperate in this genus. However, recent exploration proved quite the opposite and revealed a wealth of Oxalis species, including at least ten undescribed species and many significant range extensions of known taxa. We are in the process of describing these new species, but an overarching work, placing the abundant new knowledge in the context of southern African Oxalis , is necessary. In this study we revise the state of knowledge regarding Richtersveld Oxalis and provide brief descriptions, diagnostic characters and a morphological identification key for the 20 species confirmed to occur in the region. Nine of the ten new species are currently only known from the Richtersveld, with seven having extremely limited known distributions. Surprisingly, levels of endemism in the Richtersveld are higher than the relatively well-explored central Namaqualand Oxalis flora, and suggest that, far from being depauperate in Oxalis , the Richtersveld region should be considered a centre of endemism for the genus in southern Africa.
