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H Hartmann - One of the best experts on this subject based on the ideXlab platform.
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phylogenetic relationships in the southern african genus drosanthemum ruschioideae Aizoaceae
PeerJ, 2020Co-Authors: Sigrid Liedeschumann, Ulrich Meve, Guido W Grimm, Nicolai M Nurk, Alastair J Potts, H HartmannAbstract:Background Drosanthemum, the only genus of the tribe Drosanthemeae, is widespread over the Greater Cape Floristic Region in southern Africa. With 114 recognized species, Drosanthemum, together with the highly succulent and species-rich tribe Ruschieae, constitute the 'core ruschioids' in Aizoaceae. Within Drosanthemum, nine subgenera have been described based on flower and fruit morphology. Their phylogenetic relationships, however, have not yet been investigated, hampering understanding of monophyletic entities and patterns of geographic distribution. Methods Using chloroplast and nuclear DNA sequence data, we performed network- and tree-based phylogenetic analyses of 73 species of Drosanthemum with multiple accessions for widespread species. A well-curated, geo-referenced occurrence dataset comprising the 134 genetically analysed and 863 further accessions was used to describe the distributional ranges of intrageneric lineages and the genus as a whole. Results Phylogenetic inference supports nine clades within Drosanthemum, seven of which group in two major clades, while the remaining two show ambiguous affinities. The nine clades are generally congruent to previously described subgenera within Drosanthemum, with exceptions such as cryptic species. In-depth analyses of sequence patterns in each gene region were used to reveal phylogenetic affinities inside the retrieved clades in more detail. We observe a complex distribution pattern including widespread, species-rich clades expanding into arid habitats of the interior (subgenera Drosanthemum p.p., Vespertina, Xamera) that are genetically and morphologically diverse. In contrast, less species-rich, genetically less divergent, and morphologically unique lineages are restricted to the central Cape region and more mesic conditions (Decidua, Necopina, Ossicula, Quastea, Quadrata, Speciosa). Our results suggest that the main lineages arose from an initial rapid radiation, with subsequent diversification in some clades.
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phylogenetic relationships in the southern african genus drosanthemum ruschioideae Aizoaceae
bioRxiv, 2019Co-Authors: Sigrid Liedeschumann, Ulrich Meve, Guido W Grimm, Nicolai M Nurk, Alastair J Potts, H HartmannAbstract:Background: Drosanthemum, the only genus of the tribe Drosanthemeae, is widespread over the Greater Cape Floristic Region in southern Africa. With 114 recognized species, Drosanthemum together with the highly succulent and species-rich tribe Ruschieae constitute the 9core ruschioids9 in Aizoaceae. Within Drosanthemum, nine subgenera have been described based on flower and fruit morphology. Their phylogenetic relationships, however, have not yet been investigated, hampering understanding of monophyletic entities and patterns of geographic distribution. Methods: Using chloroplast and nuclear DNA sequence data, we performed network- and tree-based phylogenetic analyses of 73 species represented by multiple accessions of Drosanthemum. A well-curated, geo-referenced occurrence data set comprising the phylogenetically studied and 867 further accessions was used to describe the distributional ranges of intrageneric lineages and the genus as a whole. Results: Phylogenetic inference supports nine clades within Drosanthemum, seven of them group in two major clades, while the remaining two show ambiguous affinities. The nine clades are generally congruent to previously described subgenera within Drosanthemum, with exceptions such as (pseudo-) cryptic species. In-depth analyses of sequence patterns in each gene region revealed phylogenetic affinities not obvious in the phylogenetic tree. We observe a complex distribution pattern including widespread, species-rich clades expanding into arid habitats of the interior (subgenera Drosanthemum p.p., Vespertina, Xamera) that are molecular and morphologically diverse. In contrast, less species-rich, molecularly less divergent, and morphologically unique lineages are restricted to the central Cape region and more mesic conditions (Decidua, Necopina, Ossicula, Quastea, Quadrata, Speciosa). Our results suggest initial rapid radiation generating the main lineages, with some clades showing subsequent diversification.
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knersia gen nov an emigrant from drosanthemum ruschieae ruschioideae Aizoaceae
Bradleya, 2013Co-Authors: H Hartmann, Sigrid LiedeschumannAbstract:Summary: In a comprehensive study of the genus Drosanthemum, material was detected that differs fundamentally in molecular and morphological character states from the genus proper. Since it can neither be placed in any of the existing genera of the tribe Ruschieae, a new genus is described here, Knersia H.E.K.Hartmann & Liede gen nov., with K. diversifolia (L.Bolus) H.E.K.Hartmann & Liede comb. nov. as the single species.
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the identity of drosanthemum micans Aizoaceae
Bradleya, 2011Co-Authors: H HartmannAbstract:Summary: The identity of Drosanthemum micans is discussed and determined by analysing the lectoype Dillenius 1732: t. 215 f 282 and its extensive description; the version of the figure coloured by Dillen himself kept at the Bodleian Library, Oxford, is found to agree completely with the original description of Dillen and is hence chosen as the epitype, without which the species cannot be identified. The only other studied coloured image of the same engraving, however, must be excluded as being too imaginative to meet the subject of Dillenius. Furthermore, character states of growth, leaves, black filamentous staminodes, and fruits are found to present reliable features for the species, making identification independent from features of the flower, which, however, also offers distinctive character states in its morphology.
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variation in flowers in cephalophyllum curtophyllum Aizoaceae
Bradleya, 2010Co-Authors: H HartmannAbstract:Cephalophyllum curtophyllum stands out in the genus, and also in the group Mesembryanthema, by developing compact to creeping growth forms in direct reaction to changes in water supply during the seasons. The variation of flower colour patterns as re-examined here can be related to geographical factors and shows an agreement with neighbouring populations of different species, giving reason to suggest that the pollinators may play a role in the selection processes, yet no further correlation between flowers and other features can be found. The limitation of the species is confirmed, and the present corrected state of the taxonomy of the species is presented.
Sigrid Liedeschumann - One of the best experts on this subject based on the ideXlab platform.
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phylogenetic relationships in the southern african genus drosanthemum ruschioideae Aizoaceae
PeerJ, 2020Co-Authors: Sigrid Liedeschumann, Ulrich Meve, Guido W Grimm, Nicolai M Nurk, Alastair J Potts, H HartmannAbstract:Background Drosanthemum, the only genus of the tribe Drosanthemeae, is widespread over the Greater Cape Floristic Region in southern Africa. With 114 recognized species, Drosanthemum, together with the highly succulent and species-rich tribe Ruschieae, constitute the 'core ruschioids' in Aizoaceae. Within Drosanthemum, nine subgenera have been described based on flower and fruit morphology. Their phylogenetic relationships, however, have not yet been investigated, hampering understanding of monophyletic entities and patterns of geographic distribution. Methods Using chloroplast and nuclear DNA sequence data, we performed network- and tree-based phylogenetic analyses of 73 species of Drosanthemum with multiple accessions for widespread species. A well-curated, geo-referenced occurrence dataset comprising the 134 genetically analysed and 863 further accessions was used to describe the distributional ranges of intrageneric lineages and the genus as a whole. Results Phylogenetic inference supports nine clades within Drosanthemum, seven of which group in two major clades, while the remaining two show ambiguous affinities. The nine clades are generally congruent to previously described subgenera within Drosanthemum, with exceptions such as cryptic species. In-depth analyses of sequence patterns in each gene region were used to reveal phylogenetic affinities inside the retrieved clades in more detail. We observe a complex distribution pattern including widespread, species-rich clades expanding into arid habitats of the interior (subgenera Drosanthemum p.p., Vespertina, Xamera) that are genetically and morphologically diverse. In contrast, less species-rich, genetically less divergent, and morphologically unique lineages are restricted to the central Cape region and more mesic conditions (Decidua, Necopina, Ossicula, Quastea, Quadrata, Speciosa). Our results suggest that the main lineages arose from an initial rapid radiation, with subsequent diversification in some clades.
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phylogenetic relationships in the southern african genus drosanthemum ruschioideae Aizoaceae
bioRxiv, 2019Co-Authors: Sigrid Liedeschumann, Ulrich Meve, Guido W Grimm, Nicolai M Nurk, Alastair J Potts, H HartmannAbstract:Background: Drosanthemum, the only genus of the tribe Drosanthemeae, is widespread over the Greater Cape Floristic Region in southern Africa. With 114 recognized species, Drosanthemum together with the highly succulent and species-rich tribe Ruschieae constitute the 9core ruschioids9 in Aizoaceae. Within Drosanthemum, nine subgenera have been described based on flower and fruit morphology. Their phylogenetic relationships, however, have not yet been investigated, hampering understanding of monophyletic entities and patterns of geographic distribution. Methods: Using chloroplast and nuclear DNA sequence data, we performed network- and tree-based phylogenetic analyses of 73 species represented by multiple accessions of Drosanthemum. A well-curated, geo-referenced occurrence data set comprising the phylogenetically studied and 867 further accessions was used to describe the distributional ranges of intrageneric lineages and the genus as a whole. Results: Phylogenetic inference supports nine clades within Drosanthemum, seven of them group in two major clades, while the remaining two show ambiguous affinities. The nine clades are generally congruent to previously described subgenera within Drosanthemum, with exceptions such as (pseudo-) cryptic species. In-depth analyses of sequence patterns in each gene region revealed phylogenetic affinities not obvious in the phylogenetic tree. We observe a complex distribution pattern including widespread, species-rich clades expanding into arid habitats of the interior (subgenera Drosanthemum p.p., Vespertina, Xamera) that are molecular and morphologically diverse. In contrast, less species-rich, molecularly less divergent, and morphologically unique lineages are restricted to the central Cape region and more mesic conditions (Decidua, Necopina, Ossicula, Quastea, Quadrata, Speciosa). Our results suggest initial rapid radiation generating the main lineages, with some clades showing subsequent diversification.
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new species in drosanthemum Aizoaceae ruschioideae
Bradleya, 2019Co-Authors: Sigrid Liedeschumann, Ulrich Meve, Guido W GrimmAbstract:Following molecular and morphological study, four new species in Drosanthemum, belonging to the subgenera Drosanthemum, Necopina, and Speciosa, are described: D. nollothense, D. obibense, D. ecclesianum and D. brakfonteinense. In subgenus Quastea, a cryptic species imitating D. cymiferum is identified and discussed, but not formally described.
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notes on the delosperma clade Aizoaceae
Haseltonia, 2018Co-Authors: Sigrid Liedeschumann, Leonard E NewtonAbstract:47 accessions of the Delosperma-clade are analyzed using ITS and four chloroplast markers. With two exceptions, Frithia pulchra and Delosperma esterhuyseniae, all accessions are retrieved in a single, unsupported Delosperma s.l. clade. The main Delosperma s.str. clade is well supported and falls in three subclades, one comprising the two Mestoklema accessions, the other two mainly Delosperma accessions, but also Corpuscularia and Ectotropis. These genera are therefore subsumed under Delosperma. Trichodiadema accessions are retrieved in several places inside the Delosperma s.l. clade. The East African-Arabian Delosperma species are monophyletic if D. alpina from the Drakensberg is included; but they are not monophyletic with the species from Madagascar and Reunion. The species of the Central Plateau of southern Africa are also monophyletic and sister to the East African-Arabian species. Two new species, Delosperma heidihartmanniae and D. melepoense, are here described in the East African-Arabian clade.
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knersia gen nov an emigrant from drosanthemum ruschieae ruschioideae Aizoaceae
Bradleya, 2013Co-Authors: H Hartmann, Sigrid LiedeschumannAbstract:Summary: In a comprehensive study of the genus Drosanthemum, material was detected that differs fundamentally in molecular and morphological character states from the genus proper. Since it can neither be placed in any of the existing genera of the tribe Ruschieae, a new genus is described here, Knersia H.E.K.Hartmann & Liede gen nov., with K. diversifolia (L.Bolus) H.E.K.Hartmann & Liede comb. nov. as the single species.
Ulrich Meve - One of the best experts on this subject based on the ideXlab platform.
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phylogenetic relationships in the southern african genus drosanthemum ruschioideae Aizoaceae
PeerJ, 2020Co-Authors: Sigrid Liedeschumann, Ulrich Meve, Guido W Grimm, Nicolai M Nurk, Alastair J Potts, H HartmannAbstract:Background Drosanthemum, the only genus of the tribe Drosanthemeae, is widespread over the Greater Cape Floristic Region in southern Africa. With 114 recognized species, Drosanthemum, together with the highly succulent and species-rich tribe Ruschieae, constitute the 'core ruschioids' in Aizoaceae. Within Drosanthemum, nine subgenera have been described based on flower and fruit morphology. Their phylogenetic relationships, however, have not yet been investigated, hampering understanding of monophyletic entities and patterns of geographic distribution. Methods Using chloroplast and nuclear DNA sequence data, we performed network- and tree-based phylogenetic analyses of 73 species of Drosanthemum with multiple accessions for widespread species. A well-curated, geo-referenced occurrence dataset comprising the 134 genetically analysed and 863 further accessions was used to describe the distributional ranges of intrageneric lineages and the genus as a whole. Results Phylogenetic inference supports nine clades within Drosanthemum, seven of which group in two major clades, while the remaining two show ambiguous affinities. The nine clades are generally congruent to previously described subgenera within Drosanthemum, with exceptions such as cryptic species. In-depth analyses of sequence patterns in each gene region were used to reveal phylogenetic affinities inside the retrieved clades in more detail. We observe a complex distribution pattern including widespread, species-rich clades expanding into arid habitats of the interior (subgenera Drosanthemum p.p., Vespertina, Xamera) that are genetically and morphologically diverse. In contrast, less species-rich, genetically less divergent, and morphologically unique lineages are restricted to the central Cape region and more mesic conditions (Decidua, Necopina, Ossicula, Quastea, Quadrata, Speciosa). Our results suggest that the main lineages arose from an initial rapid radiation, with subsequent diversification in some clades.
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phylogenetic relationships in the southern african genus drosanthemum ruschioideae Aizoaceae
bioRxiv, 2019Co-Authors: Sigrid Liedeschumann, Ulrich Meve, Guido W Grimm, Nicolai M Nurk, Alastair J Potts, H HartmannAbstract:Background: Drosanthemum, the only genus of the tribe Drosanthemeae, is widespread over the Greater Cape Floristic Region in southern Africa. With 114 recognized species, Drosanthemum together with the highly succulent and species-rich tribe Ruschieae constitute the 9core ruschioids9 in Aizoaceae. Within Drosanthemum, nine subgenera have been described based on flower and fruit morphology. Their phylogenetic relationships, however, have not yet been investigated, hampering understanding of monophyletic entities and patterns of geographic distribution. Methods: Using chloroplast and nuclear DNA sequence data, we performed network- and tree-based phylogenetic analyses of 73 species represented by multiple accessions of Drosanthemum. A well-curated, geo-referenced occurrence data set comprising the phylogenetically studied and 867 further accessions was used to describe the distributional ranges of intrageneric lineages and the genus as a whole. Results: Phylogenetic inference supports nine clades within Drosanthemum, seven of them group in two major clades, while the remaining two show ambiguous affinities. The nine clades are generally congruent to previously described subgenera within Drosanthemum, with exceptions such as (pseudo-) cryptic species. In-depth analyses of sequence patterns in each gene region revealed phylogenetic affinities not obvious in the phylogenetic tree. We observe a complex distribution pattern including widespread, species-rich clades expanding into arid habitats of the interior (subgenera Drosanthemum p.p., Vespertina, Xamera) that are molecular and morphologically diverse. In contrast, less species-rich, molecularly less divergent, and morphologically unique lineages are restricted to the central Cape region and more mesic conditions (Decidua, Necopina, Ossicula, Quastea, Quadrata, Speciosa). Our results suggest initial rapid radiation generating the main lineages, with some clades showing subsequent diversification.
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new species in drosanthemum Aizoaceae ruschioideae
Bradleya, 2019Co-Authors: Sigrid Liedeschumann, Ulrich Meve, Guido W GrimmAbstract:Following molecular and morphological study, four new species in Drosanthemum, belonging to the subgenera Drosanthemum, Necopina, and Speciosa, are described: D. nollothense, D. obibense, D. ecclesianum and D. brakfonteinense. In subgenus Quastea, a cryptic species imitating D. cymiferum is identified and discussed, but not formally described.
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seed coat morphology of Aizoaceae sesuvioideae gisekiaceae and molluginaceae and its systematic significance
Botanical Journal of the Linnean Society, 2005Co-Authors: Nasr Sayed M Hassan, Ulrich Meve, Sigrid LiedeschumannAbstract:Macro- and micromorphological characters of the seeds of 32 species belonging to Aizoaceae (26 species), Gisekiaceae (one species) and Molluginaceae (five species) were analysed for their taxonomic value. Seed morphology is found to be of considerable taxonomic value within the taxa investigated, although additional criteria are usually necessary for distinguishing the species. However, a subgroup of Trianthema, consisting of T. cussackiana, T. megasperma, T. pilosa, T. rhynchocalyptra and T. oxycalyptra var. oxycalyptra (Aizoaceae) shares the synapomorphy of seeds with scattered idioblast cells (papillae). There is little infrageneric variation within Sesuvium and Zaleya in contrast to Trianthema, whose seeds are considerably polymorphic. The fairly different seed structures found in Aizoaceae s.s. and Molluginaceae support their treatment as two distinct families. However, the position of Lineum (Molluginaceae) remains uncertain. Moreover, seed characters support the independence of Gisekia (Gisekiaceae) in a family of its own. © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society, 2005, 148, 189–206.
Vincent Savolainen - One of the best experts on this subject based on the ideXlab platform.
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correlates of hyperdiversity in southern african ice plants Aizoaceae
Botanical Journal of the Linnean Society, 2014Co-Authors: Luis M Valente, Adam W Britton, Martyn P Powell, Alexander S T Papadopulos, Priscilla M Burgoyne, Vincent SavolainenAbstract:The exceptionally high plant diversity of the Greater Cape Floristic Region (GCFR) comprises a combination of ancient lineages and young radiations. A previous phylogenetic study of Aizoaceae subfamily Ruschioideae dated the radiation of this clade of > 1500 species in the GCFR to 3.8-8.7 Mya, establishing it as a flagship example of a diversification event triggered by the onset of a summer-arid climate in the region. However, a more recent analysis found an older age for the Ruschioideae lineage (17 Mya), suggesting that the group may in fact have originated much before the aridification of the region 10-15 Mya. Here, we reassess the tempo of radiation of ice plants by using the most complete generic-level phylogenetic tree for Aizoaceae to date, a revised calibration age and a new dating method. Our estimates of the age of the clade are even younger than initially thought (stem age 1.13-6.49 Mya), supporting the hypothesis that the radiation post-dates the establishment of an arid environment in the GCFR and firmly placing the radiation among the fastest in angiosperms (diversification rate of 4.4 species per million years). We also statistically examine environmental and morphological correlates of richness in ice plants and find that diversity is strongly linked with precipitation, temperature, topographic complexity and the evolution of highly succulent leaves and wide-band tracheids.
Cornelia Klak - One of the best experts on this subject based on the ideXlab platform.
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nomenclatural corrections in aizoon subg namibiana aizooideae Aizoaceae
Phytotaxa, 2018Co-Authors: Cornelia Klak, Peter V. BruynsAbstract:The recent study by Klak et al. (2017) showed that the species of the genera Galenia Linnaeus (1753: 359), and Plinthus Fenzl (1839: 51) should be referred to Aizoon Linnaeus (1753: 488) (Aizooideae Spreng. ex Arn., Aizoaceae Martinov). In its new circumscription, Aizoon is recognized by capsules with reduced expanding tissue, and leaves and/or stems covered by silvery hairs or hair-like to rounded papillae (see Klak et al. , 2017).
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nomenclatural novelties in cheiridopsis ruschieae Aizoaceae
Phytotaxa, 2018Co-Authors: Robyn F. Powell, Cornelia Klak, J S Boatwright, A R MageeAbstract:The recent study by Powell et al. (2017) showed that the species previously included in the genera Odontophorus N.E.Brown (1927: 12) and Ihlenfeldtia H.E.K.Hartmann (1992: 47) should be recognized under the Southern African endemic genus Cheiridopsis N.E.Brown (1925: 412) (Ruschieae Schwant. ex Ihlenf., Schwant. & Straka, Aizoaceae Martinov). In the new circumscription of Powell et al. (2017), Cheiridopsis comprises of 38 species which belong to three subgenera, i.e. subgen. Cheiridopsis N.E.Brown (1925: 412), subgen. Aequifoliae (1983: 59), and subgen. Odontophoroides H.E.K.Hartmann (1983: 59) (see Hartmann & Dehn 1987, Powell et al. 2017).
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a taxonomic revision of schlechteranthus subgenus microphyllus ruschieae Aizoaceae
Systematic Botany, 2017Co-Authors: Robyn F. Powell, Cornelia Klak, J S Boatwright, A R MageeAbstract:Schlechteranthus subgenus Microphyllus is a recently erected subgenus, which is revised here for the first time. The subgenus is comprised of nine succulent species, including a new species S. parvus, and is endemic to the arid part of the Greater Cape Floristic Region. Schlechteranthus subgenus Microphyllus can be distinguished from subgenus Schlechteranthus by the smaller leaves (3.5–5.0 × 4–6 mm vs. 5–30 × 3.5–9.0 mm) and smaller capsules (2–6 × 2–6mmvs. 6–11 × 4–9 mm), with seven to nine locules and small closing bodies that block one third of the locule (vs. 10 to 12 locules and closing bodies that block three quarters of the locule). Differences in leaf shape, degree of fusion, and arrangement, as well as inflorescence and spine structure were identified as important characters in distinguishing species in the subgenus. Schlechteranthus parvus, S. pungens, S. spinescens, and S. stylosus all share the presence of spines, caducous bracteoles, and cymose inflorescences. Maps illustrating species richness hotspots within a quarter degree square were produced for the genus and subgenera respectively. A key to the subgenera in Schlechteranthus and a comprehensive taxonomic treatment of subgenus Microphyllus is presented, including a key to the species, descriptions, figures illustrating diagnostic characters, and distribution maps.
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Phylogeny and taxonomy for Mesembryanthemum subg. Volkeranthus (Aizoaceae-Mesembryanthemoideae)
South African Journal of Botany, 2014Co-Authors: Cornelia Klak, Pavel Hanáček, Peter V. BruynsAbstract:We present a species-level phylogeny for Mesembryanthemum subg. Volkeranthus (Gerbaulet) Klak (Aizoaceae-Mesembryanthemoideae) based on four DNA markers. Previously M. subg. Volkeranthus comprised only two species, Mesembryanthemum longistylum DC. and Mesembryanthemum aitonis Jacq., which are short-lived, succulent, herbaceous perennials found in the three Cape Provinces of South Africa. Our molecular and morphological investigations suggest that the broad species concept put forward for M. aitonis Jacq. by Gerbaulet should be rejected and Mesembryanthemum paulum (N.E.Br.) L.Bolus and Mesembryanthemum clandestinum Haw., previously considered as conspecific with M. aitonis, are reinstated. Morphologically both species are distinct from M. aitonis, so that we now recognise four species in M. subg. Volkeranthus. Among the four species, the distributions of sister species overlap only marginally, but they prefer similar soils: clays for M. longistylum and M. paulum, and sandy/alluvial soils for M. clandestinum and M. aitonis. Although M. clandestinum is known in all three Cape Provinces, within this very large area it is restricted to moist sites along the banks of rivers. In contrast, M. paulum is restricted to the south-western Cape and the Agulhas Plain. Noteworthy differences between M. clandestinum and the other species in M. subg. Volkeranthus include its habit of forming large mats that survive for many years and its ability to propagate vegetatively. The inconspicuousness of its flowers and their few stamens suggest that M. clandestinum may be self-fertile. We provide an amended key to the subgenera of Mesembryanthemum and a key to M. subg. Volkeranthus, as well as synonymy and revised descriptions for its four species.
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how succulent leaves of Aizoaceae avoid mesophyll conductance limitations of photosynthesis and survive drought
Journal of Experimental Botany, 2013Co-Authors: Brad S Ripley, Cornelia Klak, Trevor Abraham, Michael D CramerAbstract:In several taxa, increasing leaf succulence has been associated with decreasing mesophyll conductance (g M) and an increasing dependence on Crassulacean acid metabolism (CAM). However, in succulent Aizoaceae, the photosynthetic tissues are adjacent to the leaf surfaces with an internal achlorophyllous hydrenchyma. It was hypothesized that this arrangement increases g M, obviating a strong dependence on CAM, while the hydrenchyma stores water and nutrients, both of which would only be sporadically available in highly episodic environments. These predictions were tested with species from the Aizoaceae with a 5-fold variation in leaf succulence. It was shown that g M values, derived from the response of photosynthesis to intercellular CO2 concentration (A:C i), were independent of succulence, and that foliar photosynthate δ13C values were typical of C3, but not CAM photosynthesis. Under water stress, the degree of leaf succulence was positively correlated with an increasing ability to buffer photosynthetic capacity over several hours and to maintain light reaction integrity over several days. This was associated with decreased rates of water loss, rather than tolerance of lower leaf water contents. Additionally, the hydrenchyma contained ~26% of the leaf nitrogen content, possibly providing a nutrient reservoir. Thus the intermittent use of C3 photosynthesis interspersed with periods of no positive carbon assimilation is an alternative strategy to CAM for succulent taxa (Crassulaceae and Aizoaceae) which occur sympatrically in the Cape Floristic Region of South Africa.