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Lectotypes for Dioscorea nummularia var. belophylla [the basionym of Dioscorea belophylla], D. kalkapershadii, D. oppositifolia and D. velutipes are designated.

International audience; The genus Dioscorea hosts a large number of yam species used medicinally and as a staple food by millions of people in tropical countries. All yams share a high antioxidant activity that correlates with their total phenolics contents. However, knowledge of edible species antioxidant phenolics remains incomplete. Bioassay-guided fractionation of the tubers of a yam species with high total phenolics content, D. nummularia, led to the isolation of two flavonols, caryatin and 3 ′-O-methyl caryatin, contributing over 92% of a stable methanol extract of the tuber in this species. Their structures were determined by high resolution mass spectrometry (HRMS), nuclear magnetic resonance (NMR) and a synthesized authentic sample. They displayed no bacterial toxicity. Their content was estimated in the tubers and bulbils of 411 landraces and hybrids belonging to eight food yam species using high performance-thin layer chromatography (HP-TLC). These were found to be highly variable at the intra-and interspecific levels to reach up to 1 030 and 457 μg/g DW respectively and added up to contents of already described antioxidant phenolics. This study provides additional understanding of the health benefits of a yam diet and constitutes the first phytochemical analysis of D. nummularia.

This study aims to explore the potential of Dioscorea nummularia Lam. and to gather information as a prelude to its improvement by plant breeding. After a taxonomic clarification and a review of the botanical data, its geographical areas of origin and distribution are determined. A germplasm survey conducted on nine islands of Vanuatu enabled the collection of 110 accessions corresponding to 84 cultivars. These were grouped into: (1) wild forms under domestication, (2) annual types, (3) perennial-type cultivars of D. nummularia and (4) natural interspecific hybrids with D. alata L. Within each group, remarkable morphological variation exists for stem spininess, leaf shape, emerging leaf colour, tuber shape and tuber flesh colour. Selected accessions examined for ploidy had chromosome numbers ranging from 2n = 3x = 60 to 2n = 6x = 120. Chloroplast counts conducted on stomatal guard cells confirmed the variation in ploidy levels. Eight different male cultivars were studied for pollen fertility, but