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A global revision of Convolvulus L. is presented, Calystegia R.Br. being excluded on pragmatic grounds. One hundred and ninety species are recognised with the greatest diversity in the Irano-Turanian region. All recognised species are described and the majority are illustrated. Distribution details, keys to species identification and taxonomic notes are provided. Four new species, Convolvulus austroafricanus J.R.I.Wood & R.W.Scotland, sp. nov., Convolvulus iranicus J.R.I.Wood & R.W.Scotland, sp. nov., Convolvulus peninsularis J.R.I.Wood & R.W.Scotland, sp. nov. and Convolvulus xanthopotamicus J.R.I.Wood & R.W.Scotland, sp. nov., one new subspecies Convolvulus chinensis subsp. triangularis J.R.I.Wood & R.W.Scotland, subsp. nov., and two new varieties Convolvulus equitans var. lindheimeri J.R.I.Wood & R.W.Scotland, var. nov., Convolvulus glomeratus var. sachalitarum J.R.I.Wood & R.W.Scotland, var. nov. are described. Convolvulus incisodentatus J.R.I.Wood & R.W.Scotland, nom. nov., is provided as a replacement name for the illegitimate Convolvulus incisus Choisy. Several species treated as synonyms of other species in recent publications are reinstated including C. chinensis Ker-Gawl., C. spinifer M.Popov., C. randii Rendle and C. aschersonii Engl. Ten taxa are given new status and recognised at new ranks: Convolvulus namaquensis (Schltr. ex. A.Meeuse) J.R.I.Wood & R.W.Scotland, stat. nov., Convolvulus hermanniae subsp. erosus (Desr.) J.R.I.Wood & R.W.Scotland, stat. nov., Convolvulus crenatifolius subsp. montevidensis (Spreng.) J.R.I.Wood & R.W.Scotland, stat. nov., Convolvulus fruticulosus subsp. glandulosus (Webb) J.R.I.Wood & R.W.Scotland, stat. nov., Convolvulus capituliferus subsp. foliaceus (Verdc.) J.R.I.Wood & R.W.Scotland, stat. nov., Convolvulus hystrix subsp. ruspolii (Dammer ex Hallier f.) J.R.I.Wood & R.W.Scotland, stat. nov., Convolvulus hystrix subsp. inermis (Chiov.) J.R.I.Wood & R.W.Scotland, stat. nov., Convolvulus rottlerianus subsp. stocksii (Boiss.) J.R.I.Wood & R.W.Scotland, comb. et stat. nov., Convolvulus calvertii subsp. ruprechtii (Boiss.) J.R.I.Wood & R.W.Scotland, stat. nov., Convolvulus cephalopodus subsp. bushiricus (Bornm.) J.R.I.Wood & R.W.Scotland, stat. nov. The status of various infraspecific taxa is clarified and numerous taxa are lectotypified. This account represents a new initiative in terms of taxonomic monography, being an attempt to bring together the global approach of the traditional monograph with the more pragmatic and identification-focussed approach of most current floras while at the same time being informed by insights from molecular systematics. [ABSTRACT FROM AUTHOR]

The stage at which DNA sequence data is incorporated into the taxonomic process and the extent of its contribution has been much discussed, but rarely in the context of assembling a taxonomic revision or monograph of a sizeable group of organisms. We present a new approach, the "foundation monograph", which incorporates DNA sequence data into a large taxonomic study in a fast and pragmatic way, thereby overhauling the taxonomy of species-rich, problematic plant groups. In this pilot study we focus on Convolvulus and use this group to exemplify how DNA barcode data can be utilised in the production of a "foundation monograph". DNA was extracted from 310 accessions, representing 140 species, most of which (285) were herbarium specimens. Samples were sequenced for the proposed plant barcoding markers rbcL, matK and ITS. Sequencing success for each marker was 74%, 49% and 63% respectively. Of the 189 species of Convolvulus recognized to date, 74% (140 species) were sampled and 68% (128 species) were successfully sequenced for at least one region. Specimen age did not impact sequencing success except in the case of matK, the longest region. Eighty percent of the species sampled exhibited combined rbcL + matK barcodes not shared with another species. The addition of ITS increased this proportion to 99%. Phylogenetic analyses of the chloroplast (152 accessions representing 90 Convolvulus species) and nuclear (200 accessions representing 112 Convolvulus species) datasets both resulted in a well-resolved and well-supported topology, and revealed four main clades with strong geographical signal. Convolvulus appeared as paraphyletic with respect to Calystegia. Species limits of eight species complexes in which morphological delimitation proved difficult and for which multiple accessions were obtained were evaluated using the phylogenetic framework as a basis. Our study highlights the utility of herbarium specimens as a source of material for DNA extractions as well as the utility of DNA barcode data in the production of a "foundation monograph", while also providing a robust, well-sampled and well-supported framework within which generic relationships, character evolution and biogeography can be investigated. [ABSTRACT FROM AUTHOR]

The sweet potato is one of the world's most widely consumed crops, yet its evolutionary history is poorly understood. In this paper, we present a comprehensive phylogenetic study of all species closely related to the sweet potato and address several questions pertaining to the sweet potato that remained unanswered. Our research combined genome skimming and target DNA capture to sequence whole chloroplasts and 605 single-copy nuclear regions from 199 specimens representing the sweet potato and all of its crop wild relatives (CWRs). We present strongly supported nuclear and chloroplast phylogenies demonstrating that the sweet potato had an autopolyploid origin and that Ipomoea trifida is its closest relative, confirming that no other extant species were involved in its origin. Phylogenetic analysis of nuclear and chloroplast genomes shows conflicting topologies regarding the monophyly of the sweet potato. The process of chloroplast capture explains these conflicting patterns, showing that I. trifida had a dual role in the origin of the sweet potato, first as its progenitor and second as the species with which the sweet potato introgressed so one of its lineages could capture an I. trifida chloroplast. In addition, we provide evidence that the sweet potato was present in Polynesia in pre-human times. This, together with several other examples of long-distance dispersal in Ipomoea, negates the need to invoke ancient human-mediated transport as an explanation for its presence in Polynesia. These results have important implications for understanding the origin and evolution of a major global food crop and question the existence of pre-Columbian contacts between Polynesia and the American continent., (Copyright © 2018 Elsevier Ltd. All rights reserved.)