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O presente trabalho compreende o levantamento florístico e o tratamento taxonômico das Malvaceae ocorrentes no Parque Estadual do Rio Doce. Foram realizadas excursões mensais no período de outubro de 1997 a janeiro de 1999 para coleta de material botânico. Os caracteres morfológicos do tubo estaminal, demonstraram ser úteis para o reconhecimento dos gêneros. Chaves acompanhadas de descrições, ilustrações, distribuição geográfica e comentários taxonômicos de cada táxon, foram realizadas. Dezenove táxons distribuídos em nove gêneros (Herissantia, Hibiscus, Malvastrum, Pavonia, Peltaea, Sida, Sidastrum, Urena e Wissadula), foram reconhecidos, sendo Sida o gênero mais representativo com sete espécies. Sida santaremensis Monteiro é nova citação de ocorrência para o Estado de Minas Gerais e Sida acuta var. obidensis Monteiro foi proposta como um sinônimo de Sida planicaulis Cav. This work consists of a taxonomy treatment of Malvaceae from Rio Doce State Park. In this way, trips were monthly accomplished from October of 1997 to January of 1999, in order to collect botanical material. The morfologic characteres of the staming tube, they were useful for the recognition of the genus. Keys for determination of genus ans species were elaborated, accompanied of descriptions, illustrations, geographical distribution and taxonomic comments of each taxon. Nineteen species were recognized, distributed in nine genus (Herissantia Medik., Hibiscus L., Malvastrum A.Gray, Pavonia Cav., Peltaea (C.Presl) Standley, Sida L., Sidastrum E.G.Baker, Urena L. and Wissadula Medik.), being Sida the most representative gender which has seven species. Sida santaremensis Monteiro is a new ocorrence citation for the State os Minas Gerais ans Sida acuta var. obidensis Monteiro was proposed as a synonym of Sida planicaulis Cav.

(Sistema reprodutivo de Oxypetalum appendiculatum Mart. e Oxypetalum banhii Roem. & Schult. subsp. banksii (Asclepiadaceae)). Estudos sobre o sistema reprodutivo de O. appendiculatum e O. banhii subsp. banhi{ foram realizados em Viçosa, MG, sudeste do Brasil. Ambas são autocompatíveis e a viabilidade das sementes, resultantes de autopol inizações e polinizações cruzadas, é alta. A baixa taxa de produção de frutos em flores de O. banhii subsp. banksii expostas aos visitantes (polinizações abertas) deve estar relacionada à falta de polinização (fator extrínseco). Em O. appendiculatum, a baixa taxa de produção de frutos deve estar relacionada a fatores intrínsecos, regulados pela planta. Polinizações interespecíficas resultaram em sementes viáveis e os híbridos FI apresentaram 64% de flores férteis; esses híbridos não foram encontrados na natureza. Autopolinizações em flores de FI resultaram em sementes também viáveis. (Breeding systems in Oxypetalum appendiculatum Mart. and Oxypetalum banhii Roem. & Schult. subsp. banhii (Asclepiadaceae)). Studies on the breeding systems of O. appendiculatum and O. banhii subsp. banhii were carried out at Viçosa, Minas Gerais State, southeastem Brazil. Both species are self-compatible and seeds that resulted from self- and cross-pollinatio'ns presented a high viability. The low rate of fruit set in O. banhii subsp. banksii flowers exposed to visitors (open pollination) may be related to the lack of pollination (extrinsic factor). In O. appendiculatum the low rate of fruit set can be related to intrinsic factors, regulated by the plant itself. Interspecific pollinations resulted in viable seeds and the FI hybrid presented 64% of fertile flowers; this hybrid has not yet been found under natural conditions. Self-pollinations in FI flowers also yielded viable seeds.

The impacts of forest fragmentation on both reproductive biology and genetic diversity of native plant species is hardly understood, despite some studies have analyzed this current worldwide problem. Since this constitutes one of the main threats to seasonal semi-deciduous forests in Southeastern Brazil, we investigated the reproductive success and the genetic diversity of a distylous, understory shrub (Psychotria hastisepala) within this context of forest fragmentation. For this study, a set of seven forest fragments of sizes ranging from 4.1 to 168.7 hectares were chosen. The intervenient matrix comprised pastures (25-50%), monocultures (33-50%) and rural roads and buildings (14-28.5%). Overall, 91 plants (54 for the short-styled morph and 37 for the long-styled morph; mean of 6.5 plants per fragment) were investigated. To evaluate reproductive success, we quantified fruit and seed production under natural pollination; to evaluate genetic diversity and population structure, we employed ISSR markers on genomic DNA. Plants with the short-styled morph exhibited a significantly higher reproductive success than those with the long-styled morph; there was no association between seed production and size of the forest fragment. Levels of genetic diversity were positively associated with the number of plants per fragment; but they were not related to flower morph. AMOVA showed that about 65% of the overall genetic variation was attributed to the differences between plants within fragments. The results suggested that populations of P. hastisepala were susceptible to decline owing to forest fragmentation.

Flowering phenology, breeding system and nectary structure of Corymborkis flava (Sw.) Kuntze were studied in a fragment of the Atlantic Forest in south-eastern Brazil. The flowering period extended from March (end of rainy season) to early June and seed dispersal occurred from June to September (dry season). Flowering peak occurred mainly in April, with up to 34 open flowers per plant being observed. The yellow, odourless and tubular flowers lasted ~7.8 days. The flowers present a perigonal nectary located in the basal lateral parts of the labellum; this is the first report on the nectary location and characterisation in the Tropidieae tribe. At the pre-anthesis stage, cells of both secretory parenchyma and epidermis of the nectary are filled with compound amyloplasts. However, starch grains were not observed in these tissues in senescent flowers, indicating that these starch grains are hydrolysed and used as source of sugars for nectar production. The nectar accumulates between the cuticle and the outer periclinal wall of the epidermal cells before flowing out into the nectar chamber. C. flava is a self-compatible species and spontaneous self-pollination does not occur because of hercogamy. The high pollinia removal (0.80) and insertion (0.82) per flower, as well as the high natural fruit-set indicate an efficient natural pollination system. The present study contributes for the knowledge of the diversity of reproductive strategies and nectary structures in Orchidaceae.

The floral biology of the tree Mabea fistulifera and the behavior of its floral visitors were studied in Vicosa, Minas Gerais State, southeastern Brazil. M. fistulifera is monoecious and self-incompatible. Its inflorescences present a female phase that lasts ten days, followed by a bisexual phase of three days during which animals exploit the nectar and pollen produced by male flowers. Pollination is effected by nocturnal as well as diurnal visitors, including mammals, birds and insects. The bats Artibeus lituratus, Vampyrops lineatus and Sturnira lilium and the opossum Didelphis marsupialis are the nocturnal pollinators. Several passerine birds and bees are the diurnal pollinators. The broad spectrum of unspecialized pollinators suggests that M. fistulifera reproduction may be little affected by disturbances of the animal community. Besides being visited by pollinators, the inflorescences are also visited by nectar thieves such as the flower bat Glossophaga soricina and hummingbirds.