Milene Faria Vieira

POLLINATION BIOLOGY OF MABEA FISTULIFERA (EUPHORBIACEAE) IN SOUTHEASTERN BRAZIL

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.

Fenologia da floração, morfologia floral e sistema de incompatibilidade em espécies distílicas de Rubiaceae em fragmento florestal do Sudeste brasileiro

This work was carried out at the Estacao de Pesquisa, Treinamento e Educacao Ambiental Mata do Paraiso, Vicosa, Minas Gerais State, a forest fragment in the Atlantic Forest. Its main objective was to analyze the flowering phenology, floral morphology, and incompatibility system of the distylous species of Rubiaceae: Palicourea longepedunculata Gardner, P. marcgravii A. St.-Hil., Psychotria conjugens Mull. Arg., P. hastisepala Mull. Arg., P. hygrophiloides Benth., P. nuda (Cham. & Schltdl.) Wawra, P. sessilis Vell. and Rudgea lanceolata Nutt. It also aimed to verify whether the floral morphs were in balanced equilibrium. The flowering in the species of Psychotria conjugens, P. hastisepala, P. hygrophiloides and P. sessilis were sequential, occurring during the rainy season (September through March). Significant differences were observed in the lengths of the stamens and styles between the thrum and pin flowers, except for P. hygrophiloides, in which only thrum flowers could be observed. Furthermore, dimorphism was observed in the length of stigmatic lobules, corollas, corolla lobules and anthers. Flowers opened in the morning lasting about 24 h, except for P. nuda flowers, that lasted 48 h. In most of the species the floral morph ratio was 1:1, except P. marcgravii, P. conjugens and P. hygrophiloides. Heteromorphic self-incompatibility was observed with growth inhibition of the incompatible pollen tubes occurring in the stigma of most of the species analyzed, except for the pin morphs of P. longepedunculata and P. hastisepala, in which reaction occurred in the style.

Distyly and variation in floral traits in natural populations of Psychotria ipecacuanha (Brot.) Stokes (Rubiaceae)

Psychotria ipecacuanha e uma especie medicinal que se desenvolve em agregados perenes, denominados reboleiras, em areas umidas e sombrias no sub-bosque da Floresta Atlântica. O presente trabalho caracterizou a variacao de atributos florais em 35 reboleiras de tres populacoes naturais desta especie. Observacoes de campo mostraram que as reboleiras sao isomorficas, isto e, apresentam apenas uma forma floral (brevistila ou longistila). Estigmas e anteras estao posicionados reciprocamente em cada forma floral, um dimorfismo caracteristico de distilia. As populacoes sao isopleticas, isto e, apresentam razao equilibrada (1:1) entre as formas florais. Analises comparativas da morfometria floral revelaram que, independente da populacao investigada, as flores brevistilas apresentaram maiores medias de comprimento da antera, comprimento do estigma, diâmetro da corola e diâmetro do grao de polen. Flores brevistilas apresentaram diferencas interpopulacionais significativas com relacao aos atributos florais investigados. Flores da forma longistila tambem apresentaram diferencas interpopulacionais significativas, exceto quanto a altura dos estigmas e ao comprimento da corola. Polinizacoes controladas conduzidas em condicoes naturais mostraram que a producao de frutos foi maior apos polinizacao legitima. Porem, observacoes de crescimento de tubos polinicos juntamente com a producao de frutos apos autopolinizacao espontânea e polinizacao ilegitima sugerem que a especie apresenta compatibilidade parcial intraforma.

Seed rain in a seasonal semideciduous forest at Viçosa, Minas Gerais State, Brazil

This study aims to evaluate the floristic composition, density and frequency of seeds in 25 traps in a section of seasonal semideciduous forest, as well as classify taxons as to life form, dispersal syndromes, and succession phase of the tree species, and verify floristic similarities between seed rain species and tree species located in the same plots. The work was carried out from December/2004 to November/2006. Forty three taxons were recognized and Leguminosae was represented by 11 species. The dominant life form was arboreal (63.1%), climbers were represented by 28.9% of the sampled species, herbs by 5.3% and shrubs by 2.6%. Mean seed density in the first year was 113.92 seeds.m-2 and 2603.84 seeds.m-2 in the second year. These differences showed spatial and seasonal heterogeneity of the seed rain. Floristic similarity using Sorensens index between seed-rain species and tree species from the studied fragment was 32%, a value considered to be low (< 50%). This result showed that the adjacent arboreal vegetation composition had little influence on the seed rain.

Trioecy in Coccoloba cereifera Schwacke (Polygonaceae), a narrow endemic and threatened tropical species

Trioecy, the co-occurrence of the males, females, and hermaphrodite morphs in natural populations, is a rare and poorly studied breeding system. It is expressed in Coccoloba cereifera, an endemic, and endangered species from the rupestrian fields of Serra do Cipo, southeastern Brazil. Male individuals produce staminate flowers but no fruits. Female individuals produce pistillate flowers and set fruits. Both staminate and pistillate flowers present non-functional organs of the opposite sex that simulate perfect flowers. Hermaphrodite individuals produce two different perfect flowers, each one belonging to distinct individuals, and set fruits. Perfect flowers differ in the amount of pollen produced, in pollen viability, and in some morphological traits. Two Hymenoptera species visited the flowers sporadically. The low natural fructification indicated a limited pollination, while the fruit set recorded in bagged pistillate flowers indicated agamospermy. Female individuals represent more than 40% of the population studied and must be the result of agamospermic seeds.

Sistema reprodutivo de Oxypetalum mexiae Malme (Asclepiadaceae), espécie endêmica de Viçosa, MG, Brasil, em perigo de extinção

Results of open-pollination (exposed flowers), in natural population, and cross and self-pollination, in cultivated individuals, are reported in O. mexiae. This species occurs at the Reserva Florestal Mata do Paraiso, a forest fragment with 195ha, whose original vegetation is part of the phytogeographic unit of the Atlantic forest. O. mexiae is a climbing species of great dimension, which grows at the wood border, following the water flow. It is self-compatible, but spontaneous self-pollination does not occur for morphological reasons. Seeds of xenogamous (40%) and autogamous (50%) fruit sets presented a high viability (respectively, 99 and 100%). No fruit was produced in natural population, indicating that this species presents reproductive limitation. This limitation is imposed by a low level of pollination, which restricts the number of fruit-set, and herbivory, which impedes the developing fruits to reach maturation. The low level of pollination may be related to habitat fragmentation. Besides, O. mexiae habitat may further limit its distribution and abundance.

Pollination of Echinodorus grandiflorus (Alismataceae)

Abstract Studies on the pollination and breeding system of Echinodorus grandiflorus (Chamisso and Schlechtendal) Micheli were carried out on two natural populations in Vicosa, Minas Gerais State, southeastern Brazil. One population was formed by individuals of ssp. grandiflorus and the other by individuals of ssp. aureus (Fassett) Haynes and Holm-Nielsen. The flowering periods were within the rainy season. Flower anthesis occurred during the morning hours and flowers lasted ca. 8 h. E. grandiflorus ssp. grandiflorus is self-incompatible; few fruits, but many adventitious plantlets are produced at the inflorescences. E. grandiflorus ssp. aureus is self-compatible; many fruits and few adventitious plantlets are formed. Bees are the main flower visitors. The bee Protodiscelis echinodori (Colletidae) presents oligolectic foraging behavior, i.e., collects pollen from a single plant species or a group of related plant species.

Malvaceae A. Juss. no Parque Estadual do Rio Doce, Minas Gerais, Brasil

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./

Flowering phenology, nectary structure and breeding system in Corymborkis flava (Spiranthoideae : Tropidieae), a terrestrial orchid from a Neotropical forest

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.

Germinação e qualidade de sementes de Adenostemma brasilianum (pers.) cass., Asteraceae nativa de sub-bosque de Floresta Atlântica

RESUMO – Foram objetivos deste estudo analisar o comportamento germinativo das sementes de Adenostemma brasilianum oriundas de populacao natural, avaliar sua qualidade fisica e verificar o seu tempo de embebicao. Sementes foram coletadas em individuos de um fragmento de Floresta Estacional Semidecidua em Vicosa, Zona da Mata mineira, Sudeste brasileiro. Para avaliacao da qualidade fisica, sementes recem-colhidas (zero mes) foram classificadas como perfeitas (escuras com embriao) ou imperfeitas (escuras ou claras, sem embriao). Amostras de 50 sementes recem-colhidas foram colocadas para germinar em tres temperaturas (20, 25 e 30 °C) e em tres condicoes de luminosidade: com suplementacao de luz (SUP), luz ambiente (AMB) e escuro continuo (ESC). A germinacao de sementes armazenadas por dois, quatro e seis meses foi testada utilizando-se metodologia identica. Sementes armazenadas por 12 e 18 meses foram colocadas para germinar a 25 oC SUP. A dormencia e a embebicao foram testadas, respectivamente, com solucao de tetrazolio e azul de metileno. Foram registradas 74,7% de sementes fisicamente perfeitas, e observou-se a partenocarpia (10%). As sementes iniciaram a germinacao ao oitavo dia apos a semeadura. Os fatores luz, temperatura e armazenamento agiram sinergeticamente sobre a germinacao das sementes. As maiores porcentagens medias de germinacao foram observadas nas sementes recem-colhidas e submetidas as temperaturas de 25 e 30 oC SUP, 85,5 e 88,5%, respectivamente. A dormencia das sementes foi constatada em baixa temperatura (20 oC), independentemente do tratamento de luz. O armazenamento aumentou a mortalidade e a quebra da dormencia; aos 12 meses, a germinacao foi nula. A absorcao de agua pela semente ocorreu 24 h apos a sua imersao em solucao de azul de metileno. Palavras-chave: Dormencia de semente, Fotoblastismo e Longevidade de semente. GERMINATION AND QUALITY OF Adenostemma brasilianum (PERS.) CASS. SEEDS, A NATIVE UNDERSTORE ASTERACEAE OF THE ATLANTIC FOREST