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Registros recuperados: 7
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A Plastid Gene Phylogeny of the Yam Genus, Dioscorea: Roots, Fruits and Madagascar Naturalis
Wilkin, P.; Schols, P.; Chase, M.; Chayamarit, K.; Furness, C.; Huysmans, S.; Rakotonasolo, F.; Smets, E.; Thapyai, C..
Following recent phylogenetic studies of the families and genera of Dioscoreales, the identification of monophyletic infrageneric taxa in the pantropical genus Dioscorea is a priority. A phylogenetic analysis based on sequence data from the plastid genes rbcL and matK is presented, using 67 species of Dioscorea and covering all the main Old World and selected New World lineages. The analysis used 14 outgroup taxa, including Trichopus Gaertn., Tacca J.R. & G. Forster, Stenomeris Planch., Burmannia L. and Thismia Griff. The main findings are: a) that a clade of rhizomatous taxa is sister to the rest of Dioscorea; b) the main Old World groups (such as the right-twining D. sect. Enantiophyllum) are monophyletic and c) there are two distinct lineages among...
Tipo: Article / Letter to the editor Palavras-chave: Dioscorea; Phylogeny; Classification; Analysis; Plastid genes; RbcL; MatK; Character evolution.
Ano: 2005 URL: http://www.repository.naturalis.nl/record/407311
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Comparative Pollen Development in Dioscoreales Naturalis
Schols, P.; Furness, C.; Merckx, V.; Wilkin, P.; Smets, E..
Pollen and orbicule ontogeny in representatives of three genera of Dioscoreales—Narthecium ossifragum Huds. (Nartheciaceae), Tacca artocarpifolia Seem. and Tacca chantrieri Andre´ (Dioscoreaceae), and Dioscorea communis (L.) Caddick & Wilkin (Dioscoreaceae)—is described and illustrated using LM, SEM, and TEM. The main difference is in microsporogenesis, which is successive in Narthecium Huds. and simultaneous in Tacca J.R. & G. Forst. and Dioscorea L. This is reflected in the tetrad configuration but not in the apertures: Narthecium and Tacca are monosulcate, while Dioscorea has two equatorial apertures. Other features of pollen development are similar in all three genera. Exine development starts at the proximal pole, and during the tetrad stage,...
Tipo: Article / Letter to the editor Palavras-chave: Intine; Microsporogenesis; Monocotyledons; Orbicules; Pollen ontogeny; Systematics; Tapetum; Tetrads.
Ano: 2005 URL: http://www.repository.naturalis.nl/record/407299
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Intervascular pit membranes with a torus in the wood of Ulmus (Ulmaceae) and related genera Naturalis
Jansen, S.; Choat, B.; Vinckier, S.; Lens, F.; Schols, P.; Smets, E..
• The distribution of intervascular pit membranes with a torus was investigated in juvenile wood samples of 19 species of Ulmus and seven related genera. • A staining solution of safranin and alcian blue (35 : 65) was recommended to distinguish torus-bearing pit membranes using light microscopy. • Intervascular pit membranes connecting relatively wide vessel elements resembled those of most angiosperms, as they were of uniform thickness. By contrast, bordered pit pairs with round to oval pit apertures and indistinct pit canals that connected narrow (incomplete) vessel elements or vascular tracheids with distinct helical thickenings were frequently characterized by a torus in ring-porous wood samples of Ulmus and Zelkova. Tori were lacking in...
Tipo: Article / Letter to the editor Palavras-chave: Ulmus (elm); Ulmaceae; Pit membrane; Torus; Pit structure; Wood anatomy; Tracheary elements; 42.58.
Ano: 2004 URL: http://www.repository.naturalis.nl/record/423388
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Palynological Characters and Their Phylogenetic Signal in Rubiaceae Naturalis
Dessein, S.; Ochoterena, H.; De Block, P.; Lens, F.; Robbrecht, E.; Schols, P.; Smets, E.; Vinckier, S.; Huysmans, S..
In the 1990s Rubiaceae became a hot spot for systematists, mainly due to the comprehensive treatment of the family by Robbrecht in 1988. Next to the exploration of macromolecular characters to infer the phylogeny, the palynology of Rubiaceae finally received the attention it deserves. This article aims to present a state-of-the-art analysis of the systematic palynology of the family. The range of variation in pollen morphology is wide, and some of the pollen features are not known from other angiosperm taxa; e.g., a looplike or spiral pattern for the position of apertures in pantoaperturate grains. We compiled an online database at the generic level for the major pollen characters and orbicule presence in Rubiaceae. An overview of the variation is...
Tipo: Article / Letter to the editor Palavras-chave: Rubiaceae; Pollen morphology; Palynology; Phylogeny.
Ano: 2005 URL: http://www.repository.naturalis.nl/record/407298
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Phylogenetic relationships in Nartheciaceae (Dioscoreales), with focus on pollen and orbicule morphology Naturalis
Merckx, V.; Schols, P.; Geuten, K.; Huysmans, S.; Smets, E.F..
Amolecular phylogenetic analysis of Nartheciaceae is presented, with nine species of the family’s five genera. The main phylogenetic findings are: (a) Nietneria and Narthecium are placed in a clade sister to Lophiola; (b) sister to the Lophiola-Narthecium- Nietneria clade is a clade formed by Aletris and the monospecific Metanarthecium; (c) the inclusion of Metanarthecium luteo-viride in Aletris, as proposed by several authors, is well supported. The pollen and orbicule morphology of representatives of five genera is described. The results underline a close relationship between Nietneria, Narthecium, and Lophiola and confirm the previously reported observations of Metanarthecium pollen and the types of sexine ornamentation in Aletris. Pollen grains of...
Tipo: Article / Letter to the editor Palavras-chave: Dioscoreales Nartheciaceae Nietneria molecular phylogeny orbicules pollen morphology 42.43; 42.48; 42.57.
Ano: 2008 URL: http://www.repository.naturalis.nl/record/449539
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Phylogeny and evolution of Burmanniaceae (Dioscoreales) based on nuclear and mitochondrial data Naturalis
Merckx, V.; Schols, P.; Maas - Van de Kamer, H.; Maas, P.; Huymans, S.; Smets, E..
The mycoheterotrophic Burmanniaceae are one of the three families currently recognized in the order Dioscoreales. Phylogenetic inference using nucleotide sequences of the nuclear 18S rDNA region and the mitochondrial nad1 b-c intron revealed two well-supported, major lineages within the family, corresponding to the two tribes recognized in the family: Burmannieae and Thismieae. All data supported a strong relationship between Thismieae and Tacca (Dioscoreaceae) making both Burmanniaceae and Dioscoreaceae polyphyletic. The three largest Burmanniaceae genera, Burmannia, Gymnosiphon, and Thismia, are paraphyletic. The splitting of Burmanniaceae into Burmannieae and Thismieae indicates two independent origins of mycoheterotrophy and correlated loss of...
Tipo: Article / Letter to the editor Palavras-chave: 18S rDNA; Burmanniaceae; Dioscoreales; Molecular phylogeny; Mycoheterotrophy; Nad1 b-c intron; Thismiaceae; 42.48.
Ano: 2006 URL: http://www.repository.naturalis.nl/record/422338
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Pollen Evolution in Yams (Dioscorea: Dioscoreaceae) Naturalis
Schols, P.; Wilkin, P.; Furness, C.; Huysmans, S.; Smets, E..
Pollen character evolution in yams (Dioscorea: Dioscoreaceae) was investigated in relation to the phylogeny obtained from a recent combined analysis of rbcL and matK gene sequences. The following characters were evaluated: pollen size, aperture number, sexine ornamentation, perforation density, and orbicule presence or absence. Continuous characters were coded using the gap weighting method. Each character was optimized using MacClade onto a tree selected at random from analyses based on molecular data of Wilkin et al. The results indicate that in Dioscorea pollen size decreases in the more derived clades. The latter observation may be related to the evolution of annually replaced tubers. Aperture number increases from one in the monosulcate Stenophora...
Tipo: Article / Letter to the editor Palavras-chave: Dioscorea; Dioscoreaceae; Pollen; Evolution; Phylogeny.
Ano: 2005 URL: http://www.repository.naturalis.nl/record/407309
Registros recuperados: 7
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