A species checklist is presented for a stretch of the seasonally flooded Macal River in the Cayo District of Belize, together with preliminary phytosociological data for the primary riverine communities. A total of 229 species were recorded in the seasonally flooded riparian zone, representing 7% of the flora of Belize. Results of quantitative sampling indicate that Inga vera subsp. vera dominates the river corridor. Other important woody associates include Cuphea calophylla, C. utriculosa, Calyptranthes bartlettii, C. lindeniana, Lindenia rivalis, Pleuranthodendron lindenii, Calliandra tergemina and Nectandra salicifolia. One of the most significant threats to riparian vegetation in the region is the Chalillo Dam upstream of the study site. The current work provides baseline floristic and ecological data for this threatened riparian habitat and documents the structure and composition of vegetation that exists downstream from the dam before its construction.

Caudella bipolaris sp. nov. (Microthyriaceae), found on leaves of the liana Bredemeyera floribunda Willd. (Polygalaceae) from the Brazilian cerrado, is described and illustrated. This is the fourth known Caudella species and the first reported on a member of the family Polygalaceae. Unique within the genus are the species' bipolar ascospore appendages.

Surveys over a period of 38 years have shown a rapid successional change in the remaining areas of cerrado vegetation in western São Paulo State. Cerradão (the dense, tall, forest form of cerrado (sensu lato)) and cerrado/Atlantic forest ecotonal vegetation have replaced more open forms (such as campo cerrado) during this period. An aerial photographic survey in 1962 showed 75% cerrado (sensu stricto), 16% campo cerrado, and only 9% cerradão, while a survey combining Landsat imaging of 1992 with aerial photography of 1984 gave 69%, 0.6%, and 30.5% respectively for the same physiognomies. Visiting 10% of the sites of the latter survey in 2000 showed that cerradão had become the dominant vegetation of 68% of them. In a particular 180 ha site in Assis municipality, cerradão increased from 12.0 to 41.4% of the area in 22 years. Reduction of anthropic pressures, such as fire and cattle-grazing, is considered responsible for these rapid changes. Conservation issues and research priorities related to these changes are discussed and proposed.

Covering an area of 177,000 hectares, the region known within Belize as the Chiquibul Forest comprises the country's largest forest reserve and includes the Chiquibul Forest Reserve, the Chiquibul National Park and the Caracol Archaeological Reserve. Based on 7047 herbarium and live collections, a checklist of 1355 species of vascular plant is presented for this area, of which 87 species are believed to be new records for the country. Of the 41 species of plant known to be endemic to Belize, four have been recorded within the Chiquibul, and 12 species are listed in The World Conservation Union (IUCN) 2006 Red List of Threatened Species. Although the Chiquibul Forest has been relatively well collected, there are geographical biases in botanical sampling which have focused historically primarily on the limestone forests of the Chiquibul Forest Reserve. A brief review of the collecting history of the Chiquibul is provided, and recommendations are given on where future collecting efforts may best be focused. The Chiquibul Forest is shown to be a significant regional centre of plant diversity and an important component of the Mesoamerican Biological Corridor.

A study was made of the transition between the cerrado and Amazonian forest biomes on the Serra do Roncador in the northeast of Mato Grosso State, Brazil. The transition was sampled by recording the species and circumference at breast height (cbh) of all woody species ≥ 15 cm cbh on five 20 × 10 m plots in each of the following four communities: ecotonal vegetation (Cerradão areas 1 and 2), and forest (Forest areas 1 and 2); while in the Cerrado sensu stricto a more rapid method had to be used because of time constraints. A total of 138 species was recorded and the results were analysed using Sørensen and Morisita Indices, TWINSPAN and DCA. In addition, comparisons were made with data from studies undertaken in 1968 in the same area by the Xavantina-Cachimbo Expedition. No species was common to all communities sampled but a seral succession of important species occurs along the transition. The Sørensen and Morisita Indices demonstrate this, with the Cerrado s.s. and Forest 2 at the two extremes showing no species in common (zero similarity) and Cerradão 1 and 2 giving the very high figures of Sørensen 0.64 and Morisita 0.84. The ecotonal cerradão is a very characteristic Dystrophic facies cerradão with Hirtella glandulosa, Emmotum nitens, Sclerolobium paniculatum and Vochysia haenkeana as its typical indicator species. The ecotone studied in the present work represents the comparatively abrupt transition from cerrado to the peripheral form of Amazonian forest (dry forest, mata seca) on flat terrain with a uniform very dystrophic soil. Other workers have suggested that this type of transition may be restricted to the headwaters of the Xingu basin, but one of the present authors has seen similar vegetation at localities in Maranhão, Rondônia, and on the Mato Grosso–Rondônia border. Comparison of the present vegetation with the survey made in 1968 shows that in this area the advancing face of the Amazonian forest has extended about 7 km southwards into the cerrado. However, in the majority of places this process has been obscured by forest clearing for agriculture. The study draws attention to the urgent need for the establishment of conservation areas in this extremely threatened and very little studied ecotone.

The floristic composition of campo limpo úmido, a moist savanna grassland vegetation of the cerrado biome, is still little described, even though its herbs and subshrubs form a major component of the cerrado vegetation. The objective of this study was to characterize the floristic richness of the herbaceous and subshrub layer of a moist grassland at the Água Fria Farm, Alto Paraíso, Goiás State (14°04′8.83″S, 47°30′33.1″W). The principal use of such grasslands is to graze cattle; in addition, local people collect vast numbers of selected species of wild plants to sell for the decorative dried plant trade, or for their medicinal qualities. Little is known, however, about the sustainability of this extractivism. A survey of a 21 ha area, with intensive quarterly collections of herbarium specimens, was made from April 2000 to March 2001. Despite the small size of the study site it proved to be very rich floristically. A total of 207 species in 90 genera and 33 families was registered in the area. Thirty-one species not yet recorded in the checklist of the flora of the cerrado biome were found in this study, plus three that seem to be new to science. The richest families were Cyperaceae (30 species), Poaceae (28), Xyridaceae (23), Eriocaulaceae (20), Asteraceae (18), and Orchidaceae and Melastomataceae with 10 species each. These results suggest the need for more research on the moist grassland to provide overall estimates for the plant species richness of this widespread vegetation type and as a basis to help guide conservation and management policies.