Kew Bulletin

A new name Besleria vernoniana Kottaim., is proposed here as a replacement name for Besleria hirsutissima C.V.Morton because the name is illegitimate and a later homonym of Besleria hirsutissima (Benth.) Fritsch.

Publication details for names that refer to the South American genus Lamanonia and its synonyms, Belangera and Polystemon, are reviewed, including names published by Vellozo, Cambessèdes, David Don, Pampanini and Engler, amongst others. The types of these names, collected by Saint-Hilaire, Glaziou, Sellow and others, are also reviewed and lectotypes designated where appropriate. A specimen of the handwriting of David Don is provided. The types of L. grandistipularis and L. speciosa are clearly conspecific and so L. speciosa is removed from the synonymy of L. ternata and now takes priority over the name L. grandistipularis for a shrub or small tree from campo rupestre in Minas Gerais and Bahia in Brazil; this species has sharply toothed, coriaceous leaves and large stipules that are usually persistent on fertile stems. A description, illustration and distribution map are provided for L. ulei, which has largely been overlooked as an accepted species, but which is distinguished from all other species in the genus by a distinctive layer of dense greyish or fawn indumentum formed of small hairs on the abaxial surface of the leaflets.

The recent revisionary work of “Merremieae” has resulted in the segregation of the c. 100 species of the pantropical genus Merremia into six genera. Thus, the formerly monotypic genus Decalobanthus was expanded, aggregating 13 species of Merremia s.l. The genus delimitation is coherent, with strong molecular phylogenetic and morphological support. Decalobanthus, hence, consists of woody climbers with broadly cordate leaves, large yellow or white flowers, four-valved chartaceous capsules, and is mostly distributed in Asia and the Pacific. Four species have remained classified in Merremia s.l., although molecular and morphological evidence unequivocally suggests their placement in Decalobanthus. In the present work, these are formally transferred to the genus, which now extends to 17 species.

The new species, Rhynchospora marliniana Naczi, W. M. Knapp & W. W. Thomas, is described, illustrated, and compared with morphologically similar species. Images are provided of its habitats, which are sunny, wet, and nutrient-poor savannas, pinelands, and streamsides in Belize, Honduras, Mexico, Nicaragua, and the southeastern USA. It is unique in Rhynchospora sect. Plumosae by having perianth bristles that are plumose only at their bases and have a smooth zone between the plumose and minutely denticulate zones. Additional diagnostic characters are dark brown proximal leaf sheaths and perianth bristles that exceed the tubercle. Rhynchospora marliniana survives burning, and quickly initiates both vegetative and reproductive growth after fire.

Although the polyphyletic genus Scirpus L. s.l. (formerly > 200 species) has been divided into more than 50 separate genera and now consists of only 64 species, its circumscription remains problematical. Three new genera have been segregated from Scirpus s.s. in the past decade, and the delimitation of Scirpus from its possible sister genus Eriophorum L. (c. 18 species) is still unresolved. The primary character used to delimit Eriophorum from Scirpus is ≥ 10 smooth, elongate perianth bristles vs ≤ 6 short, serrulate bristles or a lack of bristles, but some species display character combinations that make it difficult to place them in either genus. Eriophorum crinigerum (A. Gray) Beetle (= Scirpus criniger A. Gray), endemic to the California Floristic Province, USA, is one such species, possessing a unique combination of bristle and inflorescence features that suggest affinities with both Scirpus and Eriophorum. In this study we use molecular (matK, ndhF), morphological, and embryological data to demonstrate that E. crinigerum is not closely related to either Scirpus or Eriophorum, but represents a new generic lineage, here named Calliscirpus C. N. Gilmour, J. R. Starr & Naczi (tribe Scirpeae). Within the genus, molecular (matK, ETS 1f) and morphological data strongly support the recognition of two species, each of which is restricted to a distinct region of high endemism. Calliscirpus criniger (A. Gray) C. N. Gilmour, J. R. Starr & Naczi comb. nov. is common to the Klamath-Siskiyou and North Coast mountain ranges of Oregon and California, whereas a new species, Calliscirpus brachythrix C. N. Gilmour, J. R. Starr & Naczi, is unique to the Sierra Nevada mountain range of California. Scirpus maximowiczii C. B. Clarke, another transitional species that has blurred the limits of Scirpus and Eriophorum, and has been cited as morphologically similar to Calliscirpus species in the past, is strongly placed within a Scirpus s.s. + Eriophorum s.s. clade (100% bootstrap) on the basis of molecular and embryological data. Tree support and taxonomic sampling are not sufficient to resolve the delimitation of Eriophorum s.s. from Scirpus s.s.

Neea campanulata D.S.Costa & E.F.S.Rossetto (Nyctaginaceae, Pisonieae), a new species from southeastern Pará State in eastern Amazonian Brazil, is here described. It is distinguished from its congeners by the sessile to subsessile leaves and campanulate, incanous to yellowish puberulous staminate flowers. Comparisons with morphologically similar species and notes on the habitat, geographic distribution, conservation status and a key to the 23 species of the genus occurring in Brazil are also provided.

The invasion of native habitats by exotic, or alien, plant species has received considerable attention recently from policy, research, and practical conservation management perspectives. However, a new hypothesis for species dynamics in Britain suggests that a small number of aggressive native plant species (termed ‘thugs’) may have an equal, or greater, impact on native species and habitats than exotic species. Here, we examine this hypothesis using multivariate techniques with field-layer cover data collected during a country-wide survey of British woodlands. Multivariate analysis of these data identified a north-south gradient on the first axis, and that 20 of the 25 National Vegetation Classification woodland types were sampled within the study. The most abundant field-layer species included three of the proposed native ‘thugs’, i.e. Rubus fruticosus, Pteridium aquilinum and Hedera helix in addition to the native woodland indicator species Mercurialis perennis. Variation partitioning was used to compare the relative importance of native field-layer ‘thug’ species with invading alien shrub and tree species relative to other environmental drivers. The variation in the field-layer data-set explained by the three native ‘thug’ species was significant, but they explained a relatively small proportion of the variation relative to other environmental variables (climate, soil, management factors etc.). They did, however, explain almost four times as much variation as the three alien species that were significantly correlated with field-layer species composition (Acer pseudoplatanus, Impatiens glandulifera, Rhododendron ponticum). The results of this analysis suggest that the field-layer of British woodlands is impacted as much by native ‘thug’ species, as it is from ‘aliens’. Concern about the impact of these native ‘thug’ species has been reported previously, but their impact has not previously been compared to the impact of invading aliens. It is hoped that this analysis will do two things, first to act as a sound baseline for assessing any changing balance that should occur in the future, and second, to prompt both ecologists and conservationists to develop woodland management policies based on sound science.

Piriqueta velutina is described as a new species, illustrated, geographically mapped and its diagnostic characteristics and taxonomic affinities are described. The new species can be recognised mainly by the presence of serial branches (branches from serial buds predominantly in the apical portion of the plant), the short internodes and oblique or erect leaves which partially overlap in dried specimens; the ovate to elliptic leaf blade with a golden brown velutinous indumentum, and the conical or bulbous bases of the glandular setiform trichomes, frequently darkened on young leaf margins and on the abaxial surface. Its conservation status is preliminarily assessed as Endangered, it occurs in Brazilian Cerrado (savanna vegetation), in the Jalapão region, state of Tocantins, North region of Brazil.