Rhynchospora

Abstract: Diversity of Cyperaceae in Brazil) The purpose of this catalogue was to combine the available data from publications, theses, databases, and herbarium specimens from around 120 Herbaria, and colections sampled in Brazilian vegetation during the last 15 years to produce the most complete list, as possible as, of Cyperaceae species for Brazil. We catalogued ca. 1,700 names for 678 species in 42 genera occurring in Brazil. These values represent ca. 15 percent of the species and 40 percent of the genera found in the world. Both subfamilies of Cyperaceae are found in Brazil with Cyperoideae being the most diverse at both generic and specific levels. Although lower species were recorded for the tribes Cryptangieae, Sclerieae, and Trilepideae, these tribes represent a much higher percentage of the world's totals for genera and species. The most diverse genera are Rhynchospora (157 spp.), Cypents (101 spp.), Scleria (82 spp.) and Eleocharis (69 spp.). Fifteen genera have one species in Brazil, although five of them are monospecific. The most species-rich regions in Brazil are the North and Southeast. There are no genera endemic to Brazil. There are, however, around 200 endemic species, of which 40 are in the genus Rhynchospora. Taxonomic and nomenclatural problems found are pointed under the species. For each catalogued species, the principal synonyms, bibliographic references, distribution within Brazil's five regions, vegetation type, and citation of selected material examined are provided.

Abstract: The nature of the photosynthetic pathways of Cyperaceae found in Japan were investigated on the basis of Kranz anatomy, the CO2 compensation concentration and previously reported data. Among 301 species (96% of all cyperaceous species recorded in the region), 58 species were classified as being C4 plants. These C4 species were scattered among the tribes Fimbristylideae, Lipocarpheae, Cypereae and Rhynchosporeae in the subfamily Cyperoideae. The genera Cyperus, Eleocharis and Rhynchospora included, in Japan, both C3 and C4 species within a single genus. Using these data, an analysis was made of the ecological characteristics and geographical distribution of the C3 and C4 species in Japan. Although cyperaceous species grow in markedly different environments, the majority were found in wet and aquatic areas (61%) or shaded areas, such as forest floors (20%). Most of the C3 species were also hygrophytes (58%) and forest-living species (25%), and C3 species growing in mesic and dry areas were relatively rare. The C4 species inhabited wet and aquatic (75%), mesic (13%) and dry areas (6%) and showed marked ecological characteristics with respect to soil-moisture conditions, unlike other C4 plants, although they were absent from shaded habitats. In order to determine the climatic factors that influence the relative floristic abundance of C3 and C4 members of the Cyperaceae in Japan, the ratios of number of C4 species to the total number of members of Cyperaceae (C4 percentage) in 16 representative locales were examined in terms of various climatic variables. There were strong positive correlations between the C4 percentage and temperature. Among the C3 groups of three subfamilies, there were different distributional trends for various temperature regimes. The C3 subfamily Caricoideae increased its relative contribution to the cyperaceous flora with a decrease in mean annual temperature, while the C3 subfamily Sclerioideae exhibited the opposite pattern. The C3 group of the subfamily Cyperoideae did not show any marked change in pattern along temperature gradients, unlike the two other C3 subfamilies, and seemed to be heterogeneous in terms of its response to temperature. The relationships between the C4 biochemical subtypes and ecological characteristics are also discussed.

Abstract: The genus Rhynchospora (Cyperaceae) is a widely distributed Brazilian group, with approximately 150 species. We have studied mitosis and (or) meiosis of 16 species of four sections (Dichromena, Longirostres, Polycephalae, and Pluriflorae). The results showed high frequencies of chromosome number multiples of x = 5, which is the probable basic number. Polyploidy, in contrast to agmatoploidy and (or) symploidy, seems to be the predominant cytogenetic mechanism in the evolution of the karyotype. Primary constrictions were not visible in the chromosomes, suggesting a holocentric condition, as observed in other genera of this family. Karyotype interspecific differences were useful in the cytotaxonomic analysis in three sections. Our data propose (i) the separation of Rhynchospora ciliata (Vahl.) Kukenth. from Rhynchospora nervosa (Vahl.) Bockeler (section Dichromena), (ii) the inclusion of Rhynchospora legrandii Kukenth. ex Barros as a subspecies of Rhynchospora corymbosa (L.) Britton (section Longirostres), a...