Mycologie. — Quelques levures associ\ue9es \ue0 des insectes xylophages de la R\ue9publique Centrafricaine

Volume: 6Start Page: 5End Page: 1

Lamarck’s new species of Mesembryanthemaceae and the types of their names

The holotype of Mesembryanthemum echinatum Lam. is an unpublished, sketchy drawing kept in the Lamarck herbarium (P-LAM). The holotype of the name M. vaginatum Lam., which has not been taken up again since its original publication, is also in P-LAM. That name has priority over M. ciliatum Aiton, pertaining to a species currently placed in Brownanthus.Two new combinations are proposed: Brownanthus vaginatus (Lam.) Chesselet & M.Pignal and  Brownanthus vaginatus subsp. schenckii (Schinz) Chesselet & M.Pignal

Trois esp\ue8ces nouvelles d\u27Oleaceae et note sur la pr\ue9sence d\u27Olea capensis dans l\u27archipel des Comores

Volume: 9Start Page: 66End Page: 7

Quelques levures camerounaises

Volume: 1Start Page: 86End Page: 10

Patterns of introduction and diversification of Vanilla planifolia (Orchidaceae) in Reunion Island (Indian Ocean)

International audienceThe cultivated species Vanilla planifolia is a typical example of a crop introduced from its area of origin (America) to new regions where natural pollinators are absent. Although the Vanilla cultivars are exclusively vegetatively propagated, a high degree of phenotypic variation is observed among the cultivars in their introduction areas such as Reunion Island. To test several hypotheses explaining this variation-different introduction events, somatic mutations and sexual reproduction (through manual pollination)-we used AFLP markers to elucidate the patterns of introduction of V. planifolia. Most of the accessions cultivated in the world were derived from a single accession, possibly the Mexican cultivar Mansa. The patterns of diversification of this cultivated species were also studied and compared with other cultivated (V. tahitensis) and wild (V. pompona and V. bahiana) species. Except for one particular phenotype ('Aiguille'), which may come from sexual reproduction, cultivated accessions exhibit very low levels of genetic diversity. They have evolved by the accumulation of point mutations through vegetative multiplication. The genetic diversity revealed could not explain the phenotypic diversity, which may be related to epigenetics or polyploidy. This new understanding of the basis of genetic diversity of vanilla may assist to improve management of genetic resources. (Résumé d'auteur

Leaf functional response to increasing atmospheric CO2 concentrations over the last century in two northern Amazonian tree species: a historical delta C-13 and delta O-18 approach using herbarium samples

We assessed the extent of recent environmental changes on leaf morphological (stomatal density, stomatal surface, leaf mass per unit area) and physiological traits (carbon isotope composition, delta C-13(leaf), and discrimination, Delta C-13(leaf), oxygen isotope composition, delta O-18(leaf)) of two tropical rainforest species (Dicorynia guianensis; Humiria balsamifera) that are abundant in the Guiana shield (Northern Amazonia). Leaf samples were collected in different international herbariums to cover a 200 year time-period (1790-2004) and the whole Guiana shield. Using models describing carbon and oxygen isotope fractionations during photosynthesis, different scenarios of change in intercellular CO2 concentrations inside the leaf (C-i), stomatal conductance (g), and photosynthesis (A) were tested in order to understand leaf physiological response to increasing air CO2 concentrations (C-a). Our results confirmed that both species displayed physiological response to changing C-a. For both species, we observed a decrease of about 1.7% in delta C-13(leaf) since 1950, without significant change in Delta C-13(leaf) and leaf morphological traits. Furthermore, there was no clear change in delta O-18(leaf) for Humiria over this period. Our simulation approach revealed that an increase in A, rather than a decrease in g, explained the observed trends for these tropical rainforest species, allowing them to maintain a constant ratio of C-i/C-a