Noccaea Moench is taxonomically one of the most problematic genera of the Brassicaceae. The radical revision of Thlaspi L. s.l. by Meyer in 1973 (Meyer, 1973) split it into 12 segregate genera, including Noccaea, but subsequent molecular studies suggested that this complex includes at least four unrelated genera (Thlaspi s. str., Mummenhoffia Esmailbegi & Al-Shehbaz, Noccidium F. K. Mey., and Noccaea). Although several taxonomic treatments have since been proposed to sort out the systematic problems of Noccaea, debates are still ongoing. Some authors have argued that all segregates of Thlaspi should be considered as independent but related genera, whereas others recognize them as synonyms of a large and polymorphic Noccaea. In this study, we present the first extensively sampled phylogenetic analysis of tribe Coluteocarpeae (Thlaspi segregates including Noccaea) using internal transcribed spacer (ITS) DNA sequences from 92 of the ca. 130 species (70%) in the tribe (39 studied here for the first time) and plastidic trnL-F regions from 73 species (42 studied here for the first time), representing the full range of morphological variation and geographical distribution. All main clades are discussed in detail, and the taxonomic status of all Thlaspi s.l. segregates is evaluated against recent taxonomic treatments. In particular, the tribal placement of Noccidium is changed to Coluteocarpeae, and the genus Pseudosempervivum (Boiss.) Grossh. is reduced to synonymy of Noccaea. The new name N. mummenhoffiana Özüdoğru & Al-Shehbaz and the new combinations N. aucheri (Boiss.) Özüdoğru & Al-Shehbaz and N. sempervivum (Boiss. & Balansa) Özüdoğru & Al-Shehbaz are proposed.

A taxonomic revision of Bouchea Cham. (Duranteae, Verbenaceae) is presented, updating the last formal revision of the genus by Moldenke from 1940, with a more comprehensive and profound study of herbarium material. The analyses of the morphological features support the recognition of 13 Bouchea species. A new combination is proposed for Stachytarpheta bifurca Benth. (≡ B. bifurca (Benth.) P. Moroni & N. O'Leary), and B. boyacana Moldenke var. glabrata Moldenke is elevated to the species rank. Eight taxa are here synonymized: B. inopinata Moldenke (= B. agrestis Schauer), B. prismatica (L.) Kuntze var. brevirostra Grenzeb. (= B. bifurca), B. beckii Moldenke (= B. boliviana (Kuntze) Moldenke), B. flabelliformis M. E. Jones (= B. dissecta S. Watson), B. prismatica var. laciniata Grenzeb. (= B. dissecta), S. kingii Moldenke (= B. nelsonii Grenzeb.), B. boyacana Moldenke (= B. prismatica), and B. spathulata Torr. var. longiflora Moldenke (= B. spathulata). Lectotypes are designated for the names B. incrassata Lange (second-step), B. rusbyi Moldenke (second-step), and S. laxiflora Turcz. Furthermore, B. boliviana is reported for the first time growing in Argentina, B. notabilis Moldenke in Ecuador, and B. rusbyi in Brazil and Peru.

Elaphoglossum Schott ex J. Sm. sect. Polytrichia Christ is characterized by the presence of subulate scales and the absence of hydathodes. We did a molecular phylogenetic analysis using three non-coding plastid markers and found that five species thought to belong to section Elaphoglossum are actually members of section Polytrichia. The five species were previously thought to belong to section Elaphoglossum because they lack the characteristic subulate scales of section Polytrichia. We refer to these species as the Decursivum Group. We assign two other species to this group based on their morphological similarity to the known members of the group. Besides lacking subulate scales on the laminae, the seven species of the Decursivum Group are distinctive by having a submarginal connecting vein, a character otherwise absent in section Polytrichia. The group is entirely Neotropical, occurring at middle elevations and extending from the West Indies and Mexico to Bolivia and southeastern Brazil. For the Decursivum Group, we provide a taxonomic treatment including a key, descriptions, illustrations, distribution maps, discussion, and lists of specimens examined. Lectotypes are designated for Acrostichum miersii Baker and A. papyraceum Fée. A new species from the Andes, E. vascoae F. B. Matos & R. C. Moran, is described and illustrated.

The California Floristic Province (CA-FP) encompasses North America's Mediterranean-type climatic region and is a global biodiversity hotspot in temperate North America. Fine-scale phylogenetic studies and increasing scrutiny of morphological, ecological, and geographic variation in the CA-FP vascular flora continue to reveal novel, often cryptic diversity warranting taxonomic attention. The prevalence of such discoveries warrants caution about potential for loss of undescribed or unrecognized biodiversity from human-related impacts, including insufficiently informed conservation-related actions (e.g., genetic augmentation or assisted migration). Broader-scale molecular phylogenetic studies have yielded other examples of more extensive CA-FP diversification than previously resolved. For example, clades uniting CA-FP taxa not earlier thought to be such close relatives have been discovered in a wide diversity of tribes of composites and legumes. This understanding adds additional weight to the conclusions of Raven and Axelrod (1978) that in situ evolution, especially since the pronounced mid-Miocene transition toward summer-drying, has been a major factor in the origins of Californian vascular plant diversity. The importance of paleo-endemism in gymnosperms and (especially woody) angiosperms of the CA-FP flora also has been corroborated and refined by molecular phylogenetic studies, with improved understanding of the timing of divergence and relationships of isolated lineages, such as the extinct island-endemic Hesperelaea A. Gray (Oleaceae). On a regional scale, studies of spatial patterns of Californian species richness, phylogenetic diversity, and phylogenetic endemism by the California Plant Phylodiversity Project (CPPP) have reinforced the floristic importance of areas of high topographic complexity, or environmental heterogeneity more generally, where relatively high levels of habitat diversity, speciation, and lineage persistence may be expected. The CPPP's finding that particularly young plant lineages and significantly high phylogenetic endemism are concentrated in drier regions of the CA-FP and in the adjacent Californian deserts has corroborated earlier preliminary findings and aligns with Stebbins's (1952) hypothesis of aridity as an evolutionary stimulus. A recent conservation gap analysis by the CPPP incorporating flora-wide phylogenetic and geographic occurrence data plus land-protection status and habitat-integrity information for California has demonstrated the potential of an integrative, evolutionary approach for identifying high-priority land conservation targets.

Adaptation drives the diversity of form and function observed in nature and is key to population persistence. Yet, adaptation can be limited by a lack of genetic variation, trade-offs, small population size, and constraints imposed by coevolving interacting species. These limits may be particularly important to the colonizing populations in restored ecosystems, such as native prairies restored through seed sowing. Here, we discuss how constraints to adaptation are likely to play out in restored prairie ecosystems and how management decisions, such as seed mix composition, prescribed fire, and strategic site selection, might be used to overcome some of these constraints. Although data are still limited, recent work suggests that restored prairie populations likely face strong selection and that promoting the potential for adaptation in these systems may be necessary for restoring populations both now and in the face of further global change.

The eastern North American white oaks, a complex of approximately 16 potentially interbreeding species, have become a classic model for studying the genetic nature of species in a syngameon. Genetic work over the past two decades has demonstrated the reality of oak species, but gene flow between sympatric oaks raises the question of whether there are conserved regions of the genome that define oak species. Does gene flow homogenize the entire genome? Do the regions of the genome that distinguish a species in one part of its range differ from the regions that distinguish it in other parts of its range, where it grows in sympatry with different species? Or are there regions of the genome that are relatively conserved across species ranges? In this study, we revisit seven species of the eastern North American white oak syngameon using a set of 80 single-nucleotide polymorphisms (SNPs) selected in a previous study because they show differences among, and consistency within, the species. We test the hypothesis that there exist segments of the genome that do not become homogenized by repeated introgression, but retain distinct alleles characteristic of each species. We undertake a range-wide sampling to investigate whether SNPs that appeared to be fixed based on a relatively small sample in our previous work are fixed or nearly fixed across the range of the species. Each of the seven species remains genetically distinct across its range, given our diagnostic set of markers, with relatively few individuals exhibiting admixture of multiple species. SNPs map back to all 12 Quercus linkage groups (chromosomes) and are separated from each other by an average of 7.47 million bp (± 8.74 million bp, SD), but are significantly clustered relative to a random null distribution, suggesting that our SNP toolkit reflects genome-wide patterns of divergence while potentially being concentrated in regions of the genome that reflect a higher-than-average history of among-species divergence. This application of a DNA toolkit designed for the simple problem of identifying species in the field has two important implications. First, the eastern North American white oak syngameon is composed of entities that most taxonomists would consider “good species.” Second, and more fundamentally, species in the syngameon are genetically coherent because characteristic portions of the genome remain divergent despite a history of introgression. Understanding the conditions under which some loci diverge while others introgress is key to understanding the origins and maintenance of global tree diversity.

Trans-Beringia taxa often present complex puzzles for taxonomists, a reflection of differing traditions and opinions, taxonomic approaches, and access to material from both sides of the Bering Strait. There is wide biological variation in perceived or circumscribed taxa whose populations are widespread within the regions and yet biogeographically isolated in Asia and/or America. The Claytonia arctica complex is one such example; it illustrates these issues well and has been dealt with by North American and Russian botanists in decidedly different ways. We reviewed specimens and examined the various taxonomic concepts of C. arctica through time and source publications. The relationships (alignments) among taxonomic concepts are presented in a graphical format. We found that much of the confusion related to C. arctica in Beringia stems from overlooking C. scammaniana Hultén sensu Hultén (1939), and placing too much emphasis on the woody caudex and perennation structures, during the creation of two taxonomic concepts: C. arctica Adams sensu Porsild and C. porsildii Jurtzev sensu Yurtsev. The C. arctica complex (in our current sense) is an evolutionary work in progress, resulting in partially differentiated races with much overlapping variability and intergradation of characters (particularly in C. scammaniana according to our current sense) that have not reached the level of stability (i.e., individuals may still intergrade freely) usually associated with the concept of species in other arctic lineages.

Land-use change is among the top drivers of global biodiversity loss, which impacts the arrangement and distribution of suitable habitat for species. Population-level effects include increased isolation, decreased population size, and changes to mutualistic and antagonistic interactions. However, the extent to which species are impacted is determined by life history characteristics including dispersal. In plants, mating dynamics can be changed in ways that can negatively impact population persistence if dispersal of pollen and/or seed is disrupted. Long-distance dispersal has the potential to buffer species from the negative impacts of land-use change. Biotic vectors of long-distance dispersal have been less frequently studied, though specific taxa are known to travel great distances. Here, we describe population genetic diversity and structure in a sphingophilous species that is experiencing habitat fragmentation through land-use change, Oenothera harringtonii W. L. Wagner, Stockh. & W. M. Klein (Onagraceae). We use 12 nuclear and four plastid microsatellite markers and show that pollen dispersal by hawkmoths drives high gene flow and low population differentiation despite a range-wide gradient of land-use change and habitat fragmentation. By separating the contributions of pollen and seed dispersal to gene flow, we show that most of the genetic parameters are driven by hawkmoth-facilitated long-distance pollen dispersal, but populations with small, effective population sizes experience higher levels of relatedness and inbreeding. We discuss considerations for conservation efforts for this and other species that are pollinated by long-distance dispersers.