Cerrado Denso Research Articles

Linking the spatiotemporal variation of litterfall to standing vegetation biomass in Brazilian savannas

Abstract Aims Litterfall at a global scale is affected by climate, edaphic features and vegetation structure, with litter production increasing from grasslands to forests following the rise in standing biomass. However, at landscape scales, the same relationship between litter production and vegetation structure has rarely been studied and comparisons of litterfall patterns between adjacent, structurally distinct communities are lacking. Here, we use a standardized methodology to describe the structural differences among four savanna physiognomies and analyze their relationship with changes in litterfall across the Cerrado. Methods We evaluated the woody vegetation structure and composition in 48 sites, equally distributed across four physiognomies and monitored the monthly litter production from April 2014 to March 2015. Important Findings Results showed that the density, basal area, cylindrical volume and aboveground biomass of woody vegetation differ among physiognomies, increasing consistently from cerrado ralo, cerrado típico, cerrado denso and cerradão. Indeed, we found a strong and positive relationship between aboveground biomass and annual litter production, with litter yield increasing from 0.9 to 8.4 Mg ha−1 across different physiognomies, following the increment in vegetation structure. Monthly production was seasonal and similar among vegetation types, increasing during the dry season. Leaves comprised the dominant fraction (approx. 85%) and litterfall seasonality primarily resulted from the concentration of leaf shedding during dry months. However, the temporal pattern of litterfall throughout the year showed a gradual reduction in the seasonality from open to closed vegetation types, likely following the decrease of deciduous species abundance in the plant community. Our results showed that changes in vegetation structure may affect spatial and temporal litterfall patterns in different physiognomies, which co-occur across the Cerrado landscape, with potential implications for the overall functioning of this ecosystem. Moreover, these findings highlight the use of standardized methods as essential to correctly compare litterfall patterns among different environments.

Annual litter production in a Brazilian Cerrado woodland savanna

The Brazilian Cerrado is a heterogeneous ecosystem where annual woody-layer litter production shows strong spatiotemporal variation. Although Cerrado litter dynamics have been well-documented in forest physiognomies, knowledge from savanna habitats remains limited despite their predominance across the landscape. In this study, the fine-woody litter production and their fractions were quantified throughout the year in an area covered by the cerrado denso physiognomy (a woodland savanna) at Panga Ecological Reserve, Minas Gerais, Brazil. Using ten litter traps distributed along a 250 m transect, it was estimated that 4.44 Mg ha–1 of litter was produced annually in the cerrado denso, with leaves representing the greatest fraction (75.9%), followed by small woods (11.9%), reproductive parts (8.8%) and miscellaneous items (3.4%). Litterfall varied strongly throughout the year (monthly range: 0.17 to 1.01 Mg ha–1), and although the contribution of different fractions also varied monthly, leaves were dominant through most of the year (range: 34–94%). In fact, there was a strong positive relationship between leaf-litter biomass and the total amount of litter produced. The estimate falls within the previously recorded litter production range for the Cerrado and corresponds numerically to the position occupied by the cerrado denso physiognomy in the structural vegetation gradient in this biome. Furthermore, results indicated that litterfall in this physiognomy is strongly seasonal. Leaves represented the major part of accumulated biomass and were responsible for the increased dry season production when most woody species concentrated their leaf shedding. These results aid the understanding of the functioning of Cerrado ecosystems, and determining litterfall patterns for the entire vegetation mosaic of physiognomies is essential for the implementation of quantifiable environmental quality diagnoses and evaluations of anthropic impacts.

Optical and SAR Remote Sensing Synergism for Mapping Vegetation Types in the Endangered Cerrado/Amazon Ecotone of Nova Mutum—Mato Grosso

Mapping vegetation types through remote sensing images has proved to be effective, especially in large biomes, such as the Brazilian Cerrado, which plays an important role in the context of management and conservation at the agricultural frontier of the Amazon. We tested several combinations of optical and radar images to identify the four dominant vegetation types that are prevalent in the Cerrado area (i.e., cerrado denso, cerradão, gallery forest, and secondary forest). We extracted features from both sources of data such as intensity, grey level co-occurrence matrix, coherence, and polarimetric decompositions using Sentinel 2A, Sentinel 1A, ALOS-PALSAR 2 dual/full polarimetric, and TanDEM-X images during the dry and rainy season of 2017. In order to normalize the analysis of these features, we used principal component analysis and subsequently applied the Random Forest algorithm to evaluate the classification of vegetation types. During the dry season, the overall accuracy ranged from 48 to 83%, and during the dry and rainy seasons it ranged from 41 up to 82%. The classification using Sentinel 2A images during the dry season resulted in the highest overall accuracy and kappa values, followed by the classification that used images from all sensors during the dry and rainy season. Optical images during the dry season were sufficient to map the different types of vegetation in our study area.

Microbial Diversity in Cerrado Biome (Neotropical Savanna) Soils.

The Cerrado, the largest savanna region in South America, is located in central Brazil. Cerrado physiognomies, which range from savanna grasslands to forest formations, combined with the highly weathered, acidic clay Cerrado soils form a unique ecoregion. In this study, high-throughput sequencing of ribosomal RNA genes was combined with shotgun metagenomic analysis to explore the taxonomic composition and potential functions of soil microbial communities in four different vegetation physiognomies during both dry and rainy seasons. Our results showed that changes in bacterial, archaeal, and fungal community structures in cerrado denso, cerrado sensu stricto, campo sujo, and gallery forest soils strongly correlated with seasonal patterns of soil water uptake. The relative abundance of AD3, WPS-2, Planctomycetes, Thermoprotei, and Glomeromycota typically decreased in the rainy season, whereas the relative abundance of Proteobacteria and Ascomycota increased. In addition, analysis of shotgun metagenomic data revealed a significant increase in the relative abundance of genes associated with iron acquisition and metabolism, dormancy, and sporulation during the dry season, and an increase in the relative abundance of genes related to respiration and DNA and protein metabolism during the rainy season. These gene functional categories are associated with adaptation to water stress. Our results further the understanding of how tropical savanna soil microbial communities may be influenced by vegetation covering and temporal variations in soil moisture.

Diversity of Archaea in Brazilian savanna soils

Although the richness of Bacteria and Fungi in Cerrado' soils has been reported, here we report, for the first time, the archaeal community in Cerrado's soils. DNA extracted from soil of two distinct vegetation types, a dense subtype of sensu strict (cerrado denso) and riverbank forest (mata de galeria), was used to amplify Archaea-specific 16S rRNA gene. All of the fragments sequenced were classified as Archaea into the phylum Thaumarchaeota, predominantly affiliated to groups I.1b and I.1c. Sequences affiliated to the group I.1a were found only in the soil from riverbank forest. Soils from 'cerrado denso' had greater Archaea richness than those from 'mata de galeria' based on the richness indexes and on the rarefaction curve. β-Diversity analysis showed significant differences between the sequences from the two soil areas studied because of their different thaumarchaeal group composition. These results provide information about the third domain of life from Cerrado soils.

Aspectos florísticos da Estação Ecológica de Itapeva, SP: uma unidade de conservação no limite meridional do bioma Cerrado

A Estação Ecológica de Itapeva - EEcI (24º 04' S e 49º 04' W, altitude 750 m), Itapeva, SP, é uma Unidade de Conservação (UC) de proteção integral com cobertura vegetal predominante de cerrado denso e cerradão, cuja ocorrência na região representa o limite meridional de distribuição do cerrado sensu lato. Buscando conhecer a flora regional e supondo a existência de particularidades florísticas devido às condições climáticas locais (ausência de déficit hídrico e incidência de geadas), realizamos um levantamento florístico nesta UC entre fevereiro de 2008 a maio de 2010 e registramos 437 espécies em sete diferentes fisionomias. Nas fisionomias de cerrado sensu lato foram encontradas 346 espécies distribuídas em 87 famílias e 220 gêneros. As famílias mais ricas foram Asteraceae (31 espécies), Fabaceae (27), Myrtaceae (26), Melastomataceae (21), Rubiaceae (15), Lauraceae (12), Bignoniaceae (11) e Poaceae (10). Em relação à riqueza e famílias mais representativas, a flora da EEcI não difere de outros remanescentes de cerrado sensu lato em latitudes mais baixas. Contudo, espécies frequentes naqueles remanescentes - Dimorphandra mollis, Xylopia aromatica, Eugenia aurata e Tocoyena formosa - não foram encontradas na região da área de estudo, provavelmente devido ao efeito de geadas e outros fatores climáticos limitantes. Por outro lado, Annona dioica, Brosimum gaudichaudii, Duguetia furfuracea, Anadenanthera peregrina var. falcata, Caryocar brasiliense e Schefflera vinosa não tinham ocorrência prevista na região de Itapeva por modelos de distribuição geográfica, possivelmente devido à ausência de déficit hídrico. As informações florísticas obtidas neste estudo poderão auxiliar na parametrização desses modelos. A similaridade florística observada entre os extremos fisionômicos de cerrado sensu lato de interflúvio na EEcI: cerradão e cerrado ralo, 26%, foi menor do que a similaridade florística entre a fisionomia campestre úmida e o cerrado ralo (27%), e entre a primeira e o cerrado denso (30%). Portanto, considerando a composição florística como um dos aspectos definidores do tipo de vegetação, a fisionomia campestre úmida pode ser incluída na delimitação de cerrado sensu lato na EEcI. Foram registradas oito espécies ameaçadas de extinção. Devido às dimensões reduzidas da UC, sugerimos a sua ampliação visando maior efetividade na conservação das populações dessas espécies.

Characterization of Soil Bacterial Assemblies in Brazilian Savanna-Like Vegetation Reveals Acidobacteria Dominance

The Brazilian Cerrado is the second largest biome in Brazil and is considered a biodiversity hotspot. In this work, we compared the bacterial communities in Cerrado soil associated with four types of native vegetation (Cerrado Denso, Cerrado sensu stricto, Campo Sujo, and Mata de Galeria) by ribosomal RNA intergenic spacer analysis, terminal fragment restriction length polymorphism and pyrosequencing. The fingerprinting results were very similar. The bacterial communities of Cerrado Denso and Cerrado sensu stricto grouped together and were distinct from those in Campo Sujo and Mata de Galeria. Pyrosequencing generated approximately 40,000 16S rRNA gene sequences per sample and allowed the identification of 17 phyla in soil samples under Cerrado vegetation. Acidobacteria were dominant in all areas studied with a relative frequency of 40-47%, followed closely by Proteobacteria accounting for 34-40% of the sequences. Results from all molecular techniques used suggested that the bacterial communities of Cerrado sensu stricto and Cerrado Denso are very similar to each other, while Campo Sujo forms a separate group, and Mata de Galeria is the most distinct with higher species richness. This is the first extensive study of native Cerrado soil microbiota, an important but endangered biome.

Plant palatability to leaf-cutter ants (Atta laevigata) and litter decomposability in a Neotropical woodland savanna

Although leaf-cutter ants have been recognized as the dominant herbivore in many Neotropical ecosystems, their role in nutrient cycling remains poorly understood. Here we evaluated the relationship between plant palatability to leaf-cutter ants and litter decomposability. Our rationale was that if preference and decomposability are related, and if ant consumption changes the abundance of litter with different quality, then ant herbivory could affect litter decomposition by affecting the quality of litter entering the soil. The study was conducted in a woodland savanna (cerrado denso) area in Minas Gerais, Brazil. We compared the decomposition rate of litter produced by trees whose fresh leaves have different degrees of palatability to the leaf-cutter ant Atta laevigata. Our experiments did not indicate the existence of a significant relationship between leaf palatability to A. laevigata and leaf-litter decomposability. Although the litter mixture composed of highly palatable plant species showed, initially, a faster decay rate than the mixture of poorly palatable species, this difference was no longer visible after about 6 months. Results were consistent regardless of whether litter invertebrates were excluded or not from litter bags. Similarly, experiments comparing the decomposition rate of litter from pairs of related plant species also showed no association between plant palatability and decomposition. Decomposition rate of the more palatable species was faster, slower or similar to that of the less palatable species depending upon the particular pair of species being compared. We suggest that the traits that mostly influence the decomposition rate of litter produced by cerrado trees may not be the same as those that influence plant palatability to leaf-cutter ants. Atta laevigata select leaves of different species based – at least in part – on their nitrogen content, but N content was a poor predictor of the decomposition rates of the species we studied.

Evapotranspiration and energy balance of Brazilian savannas with contrasting tree density

Tropical savannas including those of central Brazil (Cerrado) serve as an important regulator of energy and mass exchange with the atmosphere. However, the effects of interactions between grasses and deeply rooted trees and shrubs on energy and water fluxes of savannas are not well understood. In this study, eddy-covariance measurements were used to observe and compare the energy balance and evapotranspiration at two adjacent Cerrado sites differing in woody plant density. Latent energy flux (LE) and evapotranspiration (ET) for Cerrado Denso (8–10-m trees with a cover density of approximately 50% and an understory of grass and shrubs) were generally similar to or greater than for Campo Cerrado (widely scattered 3–4-m trees with a cover density of about 5% and an understory of grasses, shrubs, and sedges), with the greatest difference between the sites occurring during the dry season. Mean annual ET was 823 and 689 mm yr −1, and LE averaged 63.9 ± 11.7 and 53.5 ± 14.3 W m −2 at Cerrado Denso and Campo Cerrado, respectively. At both sites, ET reached a minimum at near the end of the dry season, indicating that reduced water availability constrained dry season ET at both sites. The Bowen ratio at both sites increased as soil moisture decreased, but with a stronger dependency at the Campo Cerrado site, presumably due to the dominance of shallow-rooted plants and the larger contribution of soil evaporation there. Energy partitioning, as indicated by the Bowen ratio, was also strongly influenced by variations in leaf area index (LAI). The strong similarity in the Bowen ratio–LAI relationship for the two sites suggests that LAI can be used to explain much of the observed temporal and spatial ET variability across seasons and variations in woody plant density in the Cerrado.

Controls on stand transpiration and soil water utilization along a tree density gradient in a Neotropical savanna

Environmental controls of stand-level tree transpiration ( E) and seasonal patterns of soil water utilization were studied in five central Brazilian savanna (Cerrado) sites differing in tree density. Tree density of Cerrado vegetation in the study area consistently changes along topographic gradients from ∼1000 trees ha −1 in open savannas (campo sujo) at the lower end of the topographic gradient to >3000 trees ha −1 in woodlands (cerradão) at the upper end of the gradient. Tree canopy resistance ( r C) increased linearly with increasing daily mean air saturation deficit ( D) at all sites, but cerradão and cerrado denso sites with higher tree density and higher tree leaf area index (LAI) had lower r C values at all values of D compared to physiognomies with lower tree density, suggesting that r C was less sensitive to changes in D in physiognomies with high tree density and LAI . During the peak of the dry season, mean soil water potential at 0.20 m depth was most negative in the sites with the lowest tree basal area and increased linearly with basal area across sites. In contrast, soil water storage in the 0.10–2.50 m layer decreased exponentially with increasing basal area, consistent with trees in higher density sites utilizing a larger proportion of available soil water at depth during the dry season. Maximum tree transpiration was highest in the cerradão and cerrado denso (∼0.81 mm day −1). Despite higher evaporative demand during the dry season, E was similar between the dry and wet seasons within each study site, which was associated with lower LAI and canopy conductance ( g C) during the dry season compared to the wet season. Leaf area index was a good predictor of E and g C. For both dry and wet season data combined, E increased asymptotically with increasing LAI across all physiognomic types, allowing LAI to be used as a predictor of spatial variation of E. The lack of seasonality in E across the Cerrado physiognomies studied could not be explained by individual constraining variables such as D or soil water potential near the surface, but was consistent with the influence of multiple regulatory effects of D and soil water potential on seasonal changes in leaf area and g C.

Deep root function in soil water dynamics in cerrado savannas of central Brazil

Summary Water is a key resource in tropical savannas. Changes in vegetation structure due to land‐use change and increased fire frequency may affect the availability of water and the flux of water through these ecosystems. We compared the seasonal soil moisture dynamics of two adjacent savanna ecosystems with contrasting tree densities in central Brazil. Our goal was to investigate the influence of tree density on deep water uptake, soil water dynamics and evapotranspiration. Soil water was measured using a depth of 7·5 m beneath the tree‐dominated cerrado denso ecosystem and to 4 m beneath the grass‐dominated campo sujo ecosystem. Plant‐available water (PAW) throughout the cerrado denso soil profile ranged from 293 mm at the end of the dry season to 689 mm during the wet season. In the grass‐dominated site, PAW in the profile ranged from 155 to 362 mm. During the dry season, ≈82% of the water used in cerrado denso and 67% in campo sujo was extracted from the profile below 1 m. The tree‐dominated cerrado denso used 137 mm more water than the grass‐dominated campo sujo. Significant deep soil water uptake was also observed during the wet season of 1998, when rainfall was below average. Evapotranspiration (ET) rates (estimated as change in soil moisture over time) were higher in cerrado denso than in campo sujo during both seasons. Estimated ET ranged from 1·4 mm day−1 during the dry season to 5·8 mm day−1 for the wet season in cerrado denso, and from 0·9 mm day−1 in the dry season to 4·5 mm day−1 in early wet season in campo sujo. The differences in PAW and ET rates between the two ecosystems are associated not only with differences in root distribution, but also with differences in tree densities and the phenology of full‐leaf canopies. Our results suggest that deep‐rooted plants may contribute significantly to the water balance of cerrado ecosystems, and that the hydrological cycle of this biome could change as woody vegetation is replaced by exotic grasses and agricultural crops.

Fitossociologia de uma área de cerrado denso na RECOR-IBGE, Brasília-DF

Foi amostrada uma área de 10ha de cerrado denso da RECOR-IBGE, Brasília-DF. Nesta foram estabelecidas parcelas experimentais de um projeto para o estudo do efeito do fogo na vegetação do cerrado com um delineamento em blocos casualizados. Este levantamento foi efetuado antes da aplicação dos tratamentos visando conhecer a composição florística e estrutura da vegetação original. Foram incluídos todos os indivíduos lenhosos e aqueles não-lenhosos pertencentes à família Velloziaceae, com diâmetro mínimo de 5cm, presentes em cinco parcelas de 1000m². Foram medidas as alturas e os diâmetros a 30cm do solo de cada indivíduo. Ao todo foram amostrados 982 indivíduos, pertencentes a 63 espécies e a 34 famílias. Cerca de 47% das famílias foram representadas por apenas uma espécie. Apenas 16 espécies foram comuns a todas as cinco parcelas. A diversidade da área foi alta (H'= 3,53) e a similaridade entre as parcelas segundo índice de Sørensen foi também alta. As espécies Sclerolobium paniculatum, Eremanthus glomerulatus, Schefflera macrocarpum, Ouratea hexasperma, Vochysia thyrsoidea, Guapira noxia, Caryocar brasiliense, Vellozia squamata, Qualea grandiflora e Emmotum nitens apresentaram os maiores valores de importância. As estimativas de densidade e de área basal por hectare foram de 1964 indivíduos e 13,28m², respectivamente. A diversidade foi equivalente a de outras áreas de cerrado sensu stricto na região, mas a densidade e a área basal foram mais elevadas.

Dinâmica de foliação e perfilhamento de duas gramíneas C4 e uma C3 nativas do Cerrado

We compared the phenology of three native grasses at two levels of plant organization: number of leaves per tiller and number of tillers per plant. The C4 Axonopus marginatus (Trin.) Chase and Trachypogon spicatus (L.f.) Kuntze and the C3 Echinolaena inflexa (Poir.) Chase were studied in the IBGE Ecological Reserve in Brasilia, Distrito Federal, between November 1996 and June 1998. Tiller phenology was compared in three plant communities: Cerrado denso protected from fire for 26 years, campo sujo protected for 22 years and campo sujo burned every other year. Leaf phenology was studied in the protected cerrado denso only. The number of leaves of the C3 species was always greater than the C4 species. Leaf area was constant through time in the C3 species but decreased in the C4 species during the dry season. For A. marginatus and E. inflexa the number of tillers per plant was greater in the protected campo sujo, followed by the cerrado denso and the burned campo sujo. The number of tillers of T. spicatus in the protected campo sujo was twice the number of tillers in the burned campo sujo; burned campo sujo did not differ from the cerrado denso. The phenological differences between species were most evident at the leaf level. Fire caused the simplification of plant architecture (number of tillers) in all species.

Population dynamics of the lichen genus Bulbothrix Hale as potential bioindicators of ‘time‐since‐last‐fire’ in the cerrado of the Distrito Federal, central Brazil

SummaryThis paper investigates the potential use of the corticolous lichen genus Bulbothrix Hale as a bioindicator of ‘time‐since‐last‐fire’ in the cerrado (savannas) of central Brazil. Work was carried out at the Reserva Ecológica do IBGE and the Jardim Botãnico de Brasilia, 33 km outside Brasilia D.F., in plots of cerrado denso with known fire histories within the ‘Fire Project’ area. Measurements of abundance and thallus size were taken of all Bulbothrix individuals encountered up to 2 m on the trunks of three phorophyte species. The results show that abundances and thalli sizes of the Bulbothrix populations can be correlated with the ‘time‐since‐last‐fire’ that had occurred in each of the plots. This study shows that is is possible to use characteristics of specific lichen populations as bioindicators of fire history.

Ecosystem structure in the Brazilian Cerrado: a vegetation gradient of aboveground biomass, root mass and consumption by fire

Conversion to permanent agriculture is rapidly occurring over vast areas of the 1.8 million km2; Brazilian Cerrado; a region that is naturally a mosaic of grasslands, savannas and evergreen tropical woodlands. Yet, few studies have quantified total biomass of plant communities in this ecosystem, particularly the belowground component; a C pool of potential global significance. Total biomass (aboveground and belowground), and the quantity of biomass consumed by fires were measured in four plant communities comprising a vegetation gradient from pure grassland (campo limpo) to a woodland with a closed canopy of tall shrubs and scattered trees (cerrado denso) near Brasilia, DF, Brazil. Total aboveground biomass (TAGB) increased along this gradient from 5.5 Mg ha-1 in campo limpo to 29.4 Mg ha-1 in cerrado denso. Vegetation structure varied among communities; trees were nonexistent in campo limpo, but were at a density of 1000 ha-1 and a biomass of 12.9 Mg ha-1 in cerrado denso. Fires consumed 92 and 84% of the TAGB in campo limpo (pure grassland) and campo sujo (savanna), respectively. In cerrado aberto and cerrado denso, trees and tall shrubs were little affected by fire. Combustion factors of the TAGB in these communities was 54 and 33%, respectively. The total biomass consumed by fire ranged from 5.0 Mg ha-1 in campo limpo to 13.5 Mg ha-1 in cerrado aberto. Compared to other widespread Brazilian ecosystems (tropical dry forest and evergreen forest), the Cerrado has a lower aboveground biomass. The TAGB of cerrado denso is > 9% of that of Amazonian tropical evergreen forest. The total quantity of biomass consumed by fire, and hence emissions to the atmosphere is lower in intact Cerrado communities compared to fires in slashed tropical forest.

New Species of Diplusodon (Lythraceae) from Brazil

Eight new species and two new varieties from five Brazilian states are described and illustrated: Diplusodon argyrophyllus and D. ulei var. ciliatus, from Bahia; D. alatus, D. ciliatiflorus, D. oblongus var. angustifolius, D. plumbeus, and D. pygmaeus from Goiis; D. aggregatifolius, from Minas Gerais; D. trigintus, from Tocantins; and D. mattogrossensis, from Mato Grosso. Since 1985, expeditions in Brazil have been undertaken to increase knowledge of the Brazilian Lythraceae (Cavalcanti, 1987, 1988, 1990; Ramos et al., 1992) and as a basis for revising the genus Diplusodon (Cavalcanti, 1995). These efforts resulted in the collection of many interesting plants in the family, some representing rare and endemic species. In addition to new species of Cuphea, some of them already published (Cavalcanti, 1989, 1991), ten taxa of Diplusodon were confirmed to be undescribed. Diplusodon is a genus of about 65 species ranging throughout the continuous area of the Brazilian cerrado, with just 1 species occurring in the cerrado of Bolivia (Cavalcanti & Graham, 1996). The species occur different habitats, including gallery forest borders, grassy fields (campo limpo) with sandy soil, closed cerrado (cerrado denso) with trees and high shrubs, open cerrados (campo sujo), and fields with outcropping rocks (campo rupestre). In general, Diplusodon is characterized by opposite leaves, regular, hexamerous, perigynous flowers with a floral tube, two bracteoles (prophylls), and an epicalyx of six appendages. The gynoecium is bicarpellate and unilocular with an incomplete septum. The androecium can be diplostemonous, polystemonous, or rarely haplostemonous. The fruit is a septicidal capsule with winged seeds. The species of Diplusodon were first studied in detail by Koehne (1903). The most recent work, that of Lourteig (1989), described 18 new species, mainly from Minas Gerais and Goids. The new species described here further expand the diversification of the genus both in vegetative and floral characters. The etymology of the genus refers to the sepals of the calyx and the epicalyx of the flowers (diplus = double; odon = teeth). Diplusodon aggregatifolius T. Cavalcanti, sp. nov. TYPE: Brazil. Minas Gerais: Grao-Mogol, as margens do c6rrego na saida da cidade, na estrada para o Rio Ventania, 25 Feb. 1986, Cavalcanti et al. (CFCR) 9596 (holotype, SPF; isotypes, CEN, K, MBM, NY, UEC). Figure 1. Habitu, amplitudine formaque foliorum et numero staminum D. ulei appropinquat, sed hypanthio oblongo et planta omnino trichomatibus foliis evidenter ad apicem ramorum facile distinguitur. Subshrub 0.4-2.0 m, branchlets sparse, quadrangular to subquadrangular, reddish to wine-colored, pubescent; internodes 0.5-3 cm long. Leaves petiolate, petioles 3-7 mm long; venation eucamptodromous; blades chartaceous to subcoriaceous, elliptic to obovate, rarely orbicular, 0.9-3 x 0.41.2 cm, apex obtuse, margin plane to rarely slightly revolute; adaxial surface pubescent, with lateral veins inconspicuous; abaxial surface pubescent, with lateral veins 2-3, visible. Inflorescences bracteose to frondose-bracteose, diplobotrys to pleiobotrys, sometimes with accessory branches; pedicels 1-2.5 mm long; bracteoles 5-7 mm long, elliptic to obovate, with base narrow and decurrent, at the apex of pedicel, reaching to the midpoint of the floral tube. Floral tube 4-5 mm long, campanulate, pubescent; sepals wine-colored, pubescent, 2-2.5 mm long; appendages cylindrical to flattened, 22.5 mm long, spreading, slightly reflexed; corolla 2.5-3 cm diam., petals pink, 9-12 x 6-7 mm; stamens (10-)12, exserted; ovary glabrous, rounded to obconic, 2-2.8 x 1.9-2 mm; style rose, 12-19 mm long; ovules 6-14. Capsules rounded; seeds 4-6, 3-3.2 X 2-2.2 mm. Phenology. Flowering January to May; collected in fruit in April and June. Distribution. Known only from the municipio of Grao-Mogol and surroundings, in the state of Minas Gerais. Occurring in campo rupestre vegetation between 900 and 1250 m, and in cerrado vegetation at 830 m. NovoN 8: 337-351. 1998. This content downloaded from 157.55.39.158 on Fri, 18 Nov 2016 04:21:33 UTC All use subject to http://about.jstor.org/terms