Although some polyploids in the genus Polystichum are well studied and have well-resolved evolutionary histories, the origin of the circumboreally distributed allotetraploid Polystichum braunii remains obscure. We use the chloroplast markers rbcL, rps4-trnS, and trnL-F as well as the nuclear markers pgiC and gapCp to demonstrate that P. braunii is a single allotetraploid with a minimum of two origins. The two variants isolated from the nucleus resolve with divergent clades, one eastern Asian and one North American. However, they do not have near allies among morphologically appropriate taxa in our sample; the North American progenitor appears to be extinct. A divergence-time analysis based on the cpDNA markers yielded evidence of an older time of origin for P. braunii than for an array of well-known allotetraploids in the eupolypod ferns. Niche modeling in the light of geological and paleontological evidence leads to the conclusion that the two origins were in Beringia. Since P. braunii is genetically undifferentiated but widely distributed, we argue that it has expanded to its circumboreal range in the recent past, though it has a relatively ancient origin.

Calypsoinae are a small, largely temperate subtribe that are diverse with respect to trophic strategy (many species have an unusual winter leaf and several are leafless) and pollinium stalk morphology. Here we sought to re-evaluate the placement of Yoania and recently proposed genera and to examine trophic strategy, pollinium stalk type, and geographic distribution in a phylogenetic context. We analyzed ITS and matK sequences from all accepted genera using maximum likelihood and parsimony on individual and combined data sets. The only supported disagreement among trees was between the combined ML and parsimony analyses for the placement of Dactylostalix and Ephippianthus; the trees from one analysis reflected the nuclear pattern, while the other resembled the plastid pattern. A group of genera related to Calypso and a group related to Corallorhiza were resolved. Yoania is closely related to Calypso; the recently proposed Yunorchis is a species of Yoania, while Didiciea is part of Tipularia. Examining leaf morphology on the tree revealed two originations of the winter leaf morphology and four losses of leaves (and shifts to mycoheterotrophy). Pollinium stalks evolved in three directions, two of which resulted in epidermally-derived stalks (tegulae) and one that comprises the entire rostellum (a hamulus). Biogeographic analysis suggests a New World origin for the subtribe, with two major shifts to the Old World and one shift back to the New World.

Cyperaceae tribe Fuireneae consists of six genera (Actinoscirpus, Pseudoschoenus, Fuirena, Bolboschoenus, Schoenoplectus, and Schoenoplectiella) and approximately 155 species distributed widely across all continents except Antarctica. Recent molecular analyses suggest that Fuireneae is paraphyletic with respect to Cypereae, but limited taxonomic sampling and low branch support have resulted in unresolved relationships among key genera. To address the potential paraphyly of Fuireneae as well as intratribal and intertribal relationships, thirty taxa representing major lineages from the six Fuireneae genera within Cypereae were sequenced for five coding and non-coding regions from the nuclear (internal transcribed spacer, ITS) and chloroplast (trnL intron/ trnL-trnF spacer; partial ndhF, rbcL and matK genes) genomes. Maximum parsimony, maximum likelihood and Bayesian analyses of the dataset strongly support Fuireneae as a grade of three clades: (1) Fuirena, (2) Bolboschoenus and (3) a group composed of Cypereae and the four remaining Fuireneae genera (Schoenoplectus, Schoenoplectiella, Actinoscirpus, and Pseudoschoenus). Individual and combined gene trees consistently position Isolepis humillima within a well supported clade consisting of species in Schoenoplectiella sect. Schoenoplectiella. Based on molecular evidence, we transfer Isolepis humillima to Schoenoplectiella humillima, and suggest that a large-scale revision of tribal limits is required to reflect the natural relationships of the genera currently treated in Fuireneae.

The present study provides evidence for taxonomic delimitation of Digitaria sect. Trichachne based on morphological data (micro- and macromorphology) and molecular data. A phylogenetic analysis was performed using 121 morphological characters and ITS sequences of 22 species and one variety of Digitaria plus three outgroups. In all topologies (based on morphological, molecular, and combined data) Digitaria sect. Trichophorae was non-monophyletic and nested within D. sect. Trichachne. Digitaria sect. Trichophorae is thus synonymized under D. sect. Trichachne and the circumscription of D. sect. Trichachne is emended. Diagnostic morphological characters related to spikelet structure are described and documented with SEM. A key to taxa belonging to D. sect. Trichachne is provided, as well as a synopsis including synonymy, iconography, geographical distribution, and ecology. The neotype of Trichachne sacchariflora Nees is herein designated. Complete illustrations of Digitaria eggersii, D. hitchcockii, and D. patens are provided. The phylogenetic placement of the Australian species D. brownii differed among trees resulting from different data sets, thus it is provisionally not included in D. sect. Trichachne in spite of its morphological similarity. Furthermore, Megaloprotachne albescens is formally transferred to Digitaria, as Digitaria albescens.

Caamembeca (Polygalaceae) is a genus of 13 species endemic to South America. The genus is morphologically distinctive, e.g. supported by the putative morphologic synapomorphy of paired glands in a stipular position and on the rachis. However, its monophyly has not been robustly tested as only four species have been included in previous phylogenetic analyses. We present a phylogenetic analysis of 11 species based on nrITS, matK, the trnL intron, and trnL-trnF intergenic spacer. Relationships among Caamembeca species are discussed, and three new combinations are made, Caamembeca amazonensis, Caamembeca autranii, and Caamembeca formosa, providing an improved understanding of the genus.

Depending on taxonomic concept, the genus Dactyliandra (Cucurbitaceae) comprises up to four species: two from Southwest Africa, D. luederitziana (Namibia) and D. welwitschii (Angola), and two very locally distributed and poorly known taxa from Northeast Africa, D. nigrescens and D. stefaninii. In addition to these African populations, D. welwitschii was also reported as a possibly native species from the Thar desert of Northwestern India and Pakistan ca. 8,000 km away from the Namib range. A phylogenetic analysis of plastid and nuclear ribosomal ITS DNA sequences including all Dactyliandra species and D. welwitschii from the Thar desert revealed that this striking disjunction is of very recent origin. Dactyliandra is monophyletic only after exclusion of the East African taxa, which are best placed in Trochomeria. The species Dactyliandra welwitschii is monophyletic and includes the Indian plants, which group with a sample from an Angolan population. We hypothesize that this unexpected connection is a result of man-mediated introduction to India from Africa perhaps in the times of the slave trade. The new combinations Blastania lucorum and Trochomeria nigrescens are published here.

The cosmopolitan genus Elatine (Elatinaceae) includes about 25 aquatic species of mostly diminutive aquatic plants, whose relationships have not been evaluated using a phylogenetic approach. The taxonomic study of this group has been complicated by the small stature of the plants, their minute reproductive structures, and their cosmopolitan distribution. Consequently, much uncertainty exists with respect to species delimitations, their geographical distributions, and interspecific relationships. To clarify the infrageneric classification of Elatine and to provide insights on interspecific relationships within the genus, we conducted a phylogenetic study of nearly all (24) of the currently recognized species using both morphological and molecular data. The tree topology obtained based on morphological data (including vegetative and reproductive characters) was less-resolved than the trees based on molecular data, derived from either nuclear (ITS) or two plastid regions (matK/trnK and rbcL). However, the tree topology obtained from combined morphological and molecular data was well resolved and placed the morphologically distinctive E. alsinastrum as the sister group of the remaining species, which fell within two major clades: a clade of 4-merous-flowered species and a clade of 3-merous species, within which was embedded a subclade of 2-merous species. Although a number of topological differences occurred between the ITS and plastid tree topologies, significant incongruence was observed only for the placements of E. americana and E. hexandra, possibly resulting from reticulate evolution. Bergia, the sister genus of Elatine, comprises larger species, which often are mostly helophytic but never truly aquatic. Ancestral state reconstructions based on the ITS tree indicated that a morphological reduction series (in stature and floral merosity) exists among Elatine species, which is best explained as a consequence of adaptation to their aquatic life. These phylogenetic analyses also have helped to clarify the infrageneric classification of the genus and to provide a better understanding of the natural and nonindigenous distributions of the species. The new monotypic section Elatine sect. Cymifera, including E. brochonii, is described.

The study of hybridization in aquatic plants is complicated by rarity of flower production, absence of roots, and asexuality. Elatine is a cosmopolitan genus of aquatic flowering plants with about 25 species worldwide. Historically, there has been little concern regarding hybridization in the genus due to the prevalence of autogamy (i.e. self-pollination), which potentially limits xenogamous pollen transfer among the species. Two morphologically complex species (Elatine hexandra and E. americana) are the only known polyploids in the genus. In previous phylogenetic analyses, both species resolved incongruently in gene trees obtained from nuclear (ITS) versus plastid (matK/trnK and rbcL) regions. Suspecting that the phylogenetic incongruence might be a consequence of past hybridization events, we tested that hypothesis by conducting an additional phylogenetic analysis of Elatine, which incorporated sequences from a low copy nuclear gene (phyC). Elatine hexandra and E. americana were the only Elatine species exhibiting intraspecific polymorphic sites, i.e. heterozygosity, in phyC. Allele specific amplification enabled us to resolve these polymorphisms for inclusion in a phylogenetic analysis along with the monomorphic phyC sequences within species obtained for the remaining Elatine species. The phyC tree confirmed that both polyploids probably are allopolyploids, in a pattern consistent with the placement of the putative parental taxa in previous phylogenetic analyses of ITS, matK/trnK, and rbcL sequence data. The distributions of E. americana and E. hexandra, along with their potential parental species, are consistent with the proposed hybrid origins for the polyploids and provide additional clues on their geographic regions of origin.

The current study examines all genera of Sapindaceae tribe Paullinieae sensu Acevedo-Rodríguez et al. (2011). Based on molecular phylogenetic analyses of trnL intron and ITS sequence data along with critical evaluation of morphology, supertribe Paulliniodae is newly recognized and morphologically characterized by zygomorphic flowers, thyrses with lateral cincinni, corollas of 4 petals, and alternate leaves with a well-developed distal leaflet. Paulliniodae contains four successively nested subclades designated as tribes Athyaneae, Bridgesieae, Thouinieae, and Paullinieae. Athyaneae contains Athyana and Diatenopteryx, and is composed of trees with exstipulate pinnately compound leaves, and isopolar, spherical, colporate pollen grains. Bridgesieae contains the monospecific shrub genus Bridgesia with exstipulate, simple leaves, and isopolar, spherical, tricolporate pollen grains. Thouinieae is resurrected and amended to include three genera of trees or shrubs with exstipulate trifoliolate or unifoliolate leaves. Paullinieae is circumscribed to include only six genera (Thinouia, Lophostigma, Cardiospermum, Paullinia, Serjania and Urvillea) of climbers or climber-derived shrubs with stipulate leaves and a pair of inflorescence tendrils. Guindilia, previously considered a member of this clade, is shown to be more distantly related and not part of supertribe Paulliniodae. The following 14 new combinations are made to incorporate the results of our findings: Serjania biternata, Serjania cristobaliae, Serjania dissecta, Serjania guerrerensis, Serjania macrolopha, Serjania serjanioides, Serjania sonorensis, Serjania spinosa, Serjania tortuosa, Thinouia trifoliata, Urvillea cuchujaquense, Urvillea oliveirae, Urvillea procumbens, and Urvillea pterocarpa.

Wake Atoll is an isolated chain of three islets located in the Western Pacific. Included in its endemic flora is a representative of the genus Gossypium colloquially referred to as Wake Island cotton. Stanley G. Stephens pointed out that “Wake Island cotton does not resemble closely either the Caribbean or other Pacific forms.” Taking into consideration morphological distinctions, the geographic isolation of Wake Atoll, and newly generated molecular data presented here, we conclude that the cottons of Wake Atoll do in fact represent a new species of Gossypium, here named Gossypium stephensii. This name is chosen to commemorate the eminent natural historian, evolutionary geneticist, and cotton biologist, S. G. Stephens.

Sesuvium and Cypselea are closely related succulent genera within the Sesuvioideae (Aizoaceae). Since Cypselea is nested in Sesuvium in molecular studies and both genera share traits separating them from other members of the subfamily, we propose to include Cypselea in Sesuvium. Sesuvium (incl. Cypselea) comprises 14 species and is distributed worldwide with centres of diversity in southern Africa and North and Central America. Sesuvium comprises erect to procumbent herbs with opposite leaves that often bear conspicuous sheath-like lateral appendages on the petioles (pseudostipules). These and the many-seeded capsules are diagnostic traits, separating Sesuvium from the closely related genera Trianthema and Zaleya. Sesuvium is usually found in coastal or otherwise saline areas and is phylogenetically divided into an African (5 spp.) and an American lineage (9 spp.). While all African species are C₄ plants, the American lineage also comprises a derived C₃ lineage, which includes the cosmopolitan species S. portulacastrum. Some floras provide descriptions and keys for locally relevant species, but currently no comprehensive taxonomic treatment is available for Sesuvium. In this paper, a key and descriptions for all species are provided. Furthermore, we compile information on the rare and poorly known species of the genus and address issues concerning species concepts in Sesuvium, which impede species identification. The inclusion of Cypselea in Sesuvium leads to three new combinations: Sesuvium humifusum, Sesuvium mezianum and Sesuvium rubriflorum.

We infer phylogenetic relationships and test the monophyly of genera of the African Asclepias complex with three non-coding plastid DNA regions, rpl16 intron, trnC-rpoB spacer, and trnS-G spacer/trnG intron. We find that Asclepias (Trachycalymma) pseudofimbriata forms a polytomy with a clade of all other sampled African species of Asclepias s. l. and a clade of the American Asclepias s. s. Asclepias s. l. and the African species classified in Asclepias are both paraphyletic groups since segregate genera are all nested among species of African Asclepias. Most segregate genera are not monophyletic, i.e. Gomphocarpus, Pachycarpus, Stathmostelma, Xysmalobium, Schizoglossum, and Aspidoglossum; however, Glossostelma is monophyletic. Due in part to low levels of divergence in the sampled plastid markers, the approximately unbiased test did not reject the monophyly of the African species of Asclepias nor the segregate African genera, although the monophyly of Asclepias circumscribed to include American and African species but excluding currently recognized genera was rejected. Based on the results of this study, the species comprising the African Asclepias complex cannot be readily partitioned into monophyletic genera.

Field work conducted over the past fifteen years in the Sierra Juárez of Oaxaca, Mexico, has resulted in three new species of grammitid ferns and a new state distribution record. Two of the new species, Ceradenia sacksii and Lellingeria labiakii, are known only from the vicinity of Cerro Pelón and Humo Chico, in the Sierra Juárez. The third new species, Mycopteris martiniana, is also known from similar habitats in the states of Mexico and Veracruz. All three species are illustrated with line art and photographs and distinguished from their most similar relatives. The new record, Ceradenia margaritata, was previously known in Mexico from Chiapas. With these new additions, 37 species of grammitid ferns distributed in ten genera are now known from Mexico. Twenty eight of these species occur in Oaxaca, which remains the Mexican state with the overall highest diversity of ferns.

A new species of Aristolochia from the Atlantic Forest of Brazil is here described: A. insolita, from Rio de Janeiro, which belongs to subser. Hexandrae. This species, based on current knowledge, has a restricted distribution and does not occur in any conservation unit. A description, illustration, morphological comparisons, geographic distribution, and risk assessment are provided.

Rhynchospora sect. Luzuliformis is one of the 28 sections of the genus proposed by Kükenthal, the last taxonomist to have studied the section. It has three species and two varieties, and most species are found in open areas of the southern grasslands of South America. Species were studied in the field and in herbaria, and literature was reviewed. As main results we highlight the new specific status and new name, Rhynchospora boeckeleriana, the designation of two neotypes and three lectotypes, and a new record for Brazil, R. praecincta. Full descriptions of the four species are provided, as well as a key to distinguish the species of section Luzuliformes.

Ficus latipedunculata is a new species of Ficus sect. Pharmacosycea, occurring in the Brazilian Atlantic Forest, here described and illustrated. The new species shows similarities with F. adhadotifolia, F. ernanii, and F. vermifuga but differs mainly by the shape of the peduncle and basal bracts.

Lycianthes tricolor was first described (in Solanum) in 1813, based on a painting from the Sessé and Mociño expedition to New Spain. In 1904, the similar L. arrazolensis was described (also in Solanum), and since that time, plant collectors have had difficulty separating L. tricolor from L. arrazolensis. Since then four more species allied to L. tricolor and L. arrazolensis have been described: L. surotatensis in 1948, L. jalicensis in 1998, and more recently L. venturana and L. michaelneei in 2014. This article provides a key to separate the six species included in series Tricolores, with updated species descriptions, synonymy, typification, distribution, and illustrations of characteristics (i.e. stamens, seeds, calyces). We include discussion of specimens that belong in series Tricolores, but are difficult to place and require additional study, as well as the uncertain status of L. arrazolensis var. patentipila.

In the Acknowledgments section of the article “A New Species of Echeveria (Crassulaceae) from Michoacán, Mexico” by Ignacio Garcia-Ruiz, Ignacio Torres, and Mihai Costea (Systematic Botany 41: 966–970, 2016), the contributions of Guadalupe Cornejo were stated incorrectly. The first sentence of the section should read as follows: “We would like to thank Guadalupe Cornejo for providing the geographical coordinates for the locality of this species and two anonymous reviewers for their suggestions.”