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| 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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| 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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| Merckx, V.; Chatrou, L.W.; Lemaire, B.; Sainge, M.N.; Huysman, S.; Smets, E.F.. |
| Background: Myco-heterotrophy evolved independently several times during angiosperm evolution. Although many species of myco-heterotrophic plants are highly endemic and longdistance dispersal seems unlikely, some genera are widely dispersed and have pantropical distributions, often with large disjunctions. Traditionally this has been interpreted as evidence for an old age of these taxa. However, due to their scarcity and highly reduced plastid genomes our understanding about the evolutionary histories of the angiosperm myco-heterotrophic groups is poor. Results: We provide a hypothesis for the diversification of the myco-heterotrophic family Burmanniaceae. Phylogenetic inference, combined with biogeographical analyses, molecular divergence time estimates,... |
| Tipo: Article / Letter to the editor |
Palavras-chave: Myco-heterotrophy angiosperm evolution pantropical distribution reduced plastid genomes evolutionary history Burmanniaceae West Gondwana diversification boreotropical migration Eocene 42.44; 42.48; 42.57. |
| Ano: 2008 |
URL: http://www.repository.naturalis.nl/record/449529 |
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| 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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