A foundation monograph of Ipomoea (Convolvulaceae) in the New World.

A monograph of the 425 New World species of Ipomoea is presented. All 425 species are described and information is provided on their ecology and distribution, with citations from all countries from which they are reported. Notes are provided on salient characteristics and taxonomic issues related to individual species. A full synonymy is provided and 272 names are lectotypified. An extensive introduction discusses the delimitation and history of Ipomoea arguing that a broad generic concept is the only rational solution in the light of recent phylogenetic advances. Although no formal infrageneric classification is proposed, attention is drawn to the major clades of the genus and several morphologically well-defined clades are discussed including those traditionally treated under the names Arborescens, Batatas, Pharbitis, Calonyction and Quamoclit, sometimes as distinct genera, subgenera, sections or series. Identification keys are provided on a regional basis including multi-entry keys for the main continental blocks. Six species are described as new, Ipomoea nivea J.R.I. Wood & Scotland from Peru, I. apodiensis J.R.I. Wood & Scotland from Brazil, I. calcicola J.R.I. Wood & Scotland, I. pochutlensis J.R.I. Wood & Scotland, I. zacatecana J.R.I. Wood & Scotland and I. ramulosa J.R.I. Wood & Scotland from Mexico, while var. australis of I. cordatotriloba is raised to specific status as I. australis (O'Donell) J.R.I. Wood & P. Muñoz. New subspecies for I. nitida (subsp. krapovickasii J.R.I. Wood & Scotland) and for I. chenopodiifolia (subsp. bellator J.R.I. Wood & Scotland) are described. The status of previously recognized species and varieties is changed so the following new subspecies are recognized: I. amnicola subsp. chiliantha (Hallier f.) J.R.I. Wood & Scotland, I. chenopodiifolia subsp. signata (House) J.R.I. Wood & Scotland, I. orizabensis subsp. collina (House) J.R.I. Wood & Scotland, I. orizabensis subsp. austromexicana (J.A. McDonald) J.R.I. Wood & Scotland, I. orizabensis subsp. novogaliciana (J.A. McDonald) J.R.I. Wood & Scotland, I. setosa subsp. pavonii (Hallier f.) J.R.I. Wood & Scotland, I. setosa subsp. melanotricha (Brandegee) J.R.I. Wood & Scotland, I. setosa subsp. sepacuitensis (Donn. Sm.) J.R.I. Wood & Scotland, I. ternifolia subsp. leptotoma (Torr.) J.R.I. Wood & Scotland. Ipomoea angustata and I. subincana are treated as var. angustata (Brandegee) J.R.I. Wood & Scotland and var. subincana (Choisy) J.R.I. Wood & Scotland of I. barbatisepala and I. brasiliana respectively. Attention is drawn to a number of hitherto poorly recognized phenomena in the genus including a very large radiation centred on the Parana region of South America and another on the Caribbean Islands, a strong trend towards an amphitropical distribution in the New World, the existence of a relatively large number of species with a pantropical distribution and of many species in different clades with storage roots, most of which have never been evaluated for economic purposes. The treatment is illustrated with over 200 figures composed of line drawings and photographs.

A taxonomic monograph of Ipomoea integrated across phylogenetic scales.

Taxonomic monographs have the potential to make a unique contribution to the understanding of global biodiversity. However, such studies, now rare, are often considered too daunting to undertake within a realistic time frame, especially as the world's collections have doubled in size in recent times. Here, we report a global-scale monographic study of morning glories (Ipomoea) that integrated DNA barcodes and high-throughput sequencing with the morphological study of herbarium specimens. Our approach overhauled the taxonomy of this megadiverse group, described 63 new species and uncovered significant increases in net diversification rates comparable to the most iconic evolutionary radiations in the plant kingdom. Finally, we show that more than 60 species of Ipomoea, including sweet potato, independently evolved storage roots in pre-human times, indicating that the storage root is not solely a product of human domestication but a trait that predisposed the species for cultivation. This study demonstrates how the world's natural history collections can contribute to global challenges in the Anthropocene.

Reconciling Conflicting Phylogenies in the Origin of Sweet Potato and Dispersal to Polynesia.

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.

How the temperate world was colonised by bindweeds: biogeography of the Convolvuleae (Convolvulaceae).

BACKGROUND: At a global scale, the temperate zone is highly fragmented both between and within hemispheres. This paper aims to investigate how the world's disjunct temperate zones have been colonised by the pan-temperate plant group Convolvuleae, sampling 148 of the c. 225 known species. We specifically determine the number and timing of amphitropical and transoceanic disjunctions, investigate the extent to which disjunctions in Convolvuleae are spatio-temporally congruent with those in other temperate plant groups and determine the impact of long-distance dispersal events on diversification rates. RESULTS: Eight major disjunctions are observed in Convolvuleae: two Northern Hemisphere, two Southern Hemisphere and four amphitropical. Diversity in the Southern Hemisphere is largely the result of a single colonisation of Africa 3.1-6.4 Ma, and subsequent dispersals from Africa to both Australasia and South America. Speciation rates within this monophyletic, largely Southern Hemisphere group (1.38 species Myr(-1)) are found to be over twice those of the tribe as a whole (0.64 species Myr(-1)). Increased speciation rates are also observed in Calystegia (1.65 species Myr(-1)). CONCLUSIONS: The Convolvuleae has colonised every continent of the world with a temperate biome in c. 18 Myr and eight major range disjunctions underlie this broad distribution. In keeping with other temperate lineages exhibiting disjunct distributions, long-distance dispersal is inferred as the main process explaining the patterns observed although for one American-Eurasian disjunction we cannot exclude vicariance. The colonisation of the temperate zones of the three southern continents within the last c. 4 Myr is likely to have stimulated high rates of diversification recovered in this group, with lineage accumulation rates comparable to those reported for adaptive radiations.

Are there any widespread endemic flowering plant species in Macaronesia? Phylogeography of Ranunculus cortusifolius.

PREMISE OF THE STUDY: Oceanic island endemics typically exhibit very restricted distributions. In Macaronesia, only one endemic angiosperm species, Ranunculus cortusifolius, has a distribution spanning the archipelagos of the Azores, Madeira, and Canaries. Earlier work suggested possible differences between archipelagos and the multiple origins of the species. This paper tests the hypothesis that R. cortusifolius is a single widespread Macaronesian endemic species with a single origin. METHODS: Chloroplast (matK-trnK, psbJ-petA) and ITS sequences were generated from across the distribution of R. cortusifolius. Relationships were investigated using Bayesian inference and divergence times estimated using BEAST. Infraspecific variation was investigated using statistical parsimony. The general mixed Yule-coalescent model (GMYC) was further used to identify putative species boundaries based on maternally inherited plastid data. KEY RESULTS: The hypothesis of multiple independent origins of R. cortusifolius is rejected. Divergence of the R. cortusifolius lineage from a western Mediterranean sister group in the late Miocene is inferred. Distinct genotypes were resolved within R. cortusifolius that are endemic to the Azores, Madeira, and the Canaries. Four to five putative species were delimited by different versions of the GMYC model. CONCLUSION: Ranunculus cortusifolius is the result of a single colonization of Macaronesia. The large distances between archipelagos have been effective barriers to dispersal, promoting allopatric diversification at the molecular level with diversification also evident within the Canaries. Isolation has not been accompanied by marked morphological diversification, which may be explained by the typical association of R. cortusifolius with stable and climatically buffered laurel forest communities.

A foundation monograph of Convolvulus L. (Convolvulaceae).

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, Convolvulusaustroafricanus J.R.I.Wood & R.W.Scotland, sp. nov., Convolvulusiranicus J.R.I.Wood & R.W.Scotland, sp. nov., Convolvuluspeninsularis J.R.I.Wood & R.W.Scotland, sp. nov. and Convolvulusxanthopotamicus J.R.I.Wood & R.W.Scotland, sp. nov., one new subspecies Convolvuluschinensissubsp.triangularis J.R.I.Wood & R.W.Scotland, subsp. nov., and two new varieties Convolvulusequitansvar.lindheimeri J.R.I.Wood & R.W.Scotland, var. nov., Convolvulusglomeratusvar.sachalitarum J.R.I.Wood & R.W.Scotland, var. nov. are described. Convolvulusincisodentatus J.R.I.Wood & R.W.Scotland, nom. nov., is provided as a replacement name for the illegitimate Convolvulusincisus Choisy. Several species treated as synonyms of other species in recent publications are reinstated including Convolvuluschinensis Ker-Gawl., Convolvulusspinifer M.Popov., Convolvulusrandii Rendle and Convolvulusaschersonii Engl. Ten taxa are given new status and recognised at new ranks: Convolvulusnamaquensis (Schltr. ex. A.Meeuse) J.R.I.Wood & R.W.Scotland, stat. nov., Convolvulushermanniaesubsp.erosus (Desr.) J.R.I.Wood & R.W.Scotland, stat. nov., Convolvuluscrenatifoliussubsp.montevidensis (Spreng.) J.R.I.Wood & R.W.Scotland, stat. nov., Convolvulusfruticulosussubsp.glandulosus (Webb) J.R.I.Wood & R.W.Scotland, stat. nov., Convolvuluscapituliferussubsp.foliaceus (Verdc.) J.R.I.Wood & R.W.Scotland, stat. nov., Convolvulushystrixsubsp.ruspolii (Dammer ex Hallier f.) J.R.I.Wood & R.W.Scotland, stat. nov., Convolvulushystrixsubsp.inermis (Chiov.) J.R.I.Wood & R.W.Scotland, stat. nov., Convolvulusrottlerianussubsp.stocksii (Boiss.) J.R.I.Wood & R.W.Scotland, comb. et stat. nov., Convolvuluscalvertiisubsp.ruprechtii (Boiss.) J.R.I.Wood & R.W.Scotland, stat. nov., Convolvuluscephalopodussubsp.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.