Ana Angélica Almeida Barbosa

Contrasting breeding systems in twoEriotheca (Bombacaceae) species of the Brazilian cerrados

The pollination biology and breeding systems ofEriotheca pubescens andE. gracilipes have been studied. These two species occur as trees in cerrado vegetation, the neotropical savannas of Central Brazil, with partially sympatric distributions. They have similar phenology and floral structure, although the flowers ofE. pubescens are larger. Both species have nectar flowers pollinated by largeAnthophoridae bees but the main pollinators of each species differ in size. The species have markedly different breeding systems: late-acting self-incompatibility inE. gracilipes and apomixis stimulated by pollination inE. pubescens.

Composição florística de veredas no Município de Uberlândia, MG

Over a two-year period, four palm swamp communities near Uberlândia, MG, Brazil, were studied for their floristic composition. Transects were randomly established to cross the following zones: palm swamp border (dryish soils), middle area (intermediate soil moisture), and lower zone (with permanently satured soils). The transects were censused each month and voucher herbarium specimens were collected and identified by means of keys, comparisons with identified material at HUFU, IBGE and UB, and with the help of specialists for some families. Voucher specimens were deposited at HUFU. A total of 526 species, 250 genera and 89 families were collected. The five families with highest number of species were: Poaceae (64), Asteraceae (63), Cyperaceae (54), Melastomataceae (27) e Fabaceae (23). In the palm swamp border, 361 species were collected, 168 of which were exclusive to this zone. A total of 300 species were collected in the middle zone, of which 75 were exclusive to this area. The lower zone had the lowest species diversity, with 52 exclusive species from a total of 136 taxa. The great richness found in the palm swamp possibly is due to soil differences, especially those related to humidity.

Moth pollination of woody species in the Cerrados of Central Brazil: a case of so much owed to so few?

Abstract.We present a survey of moth pollination in woody species of the Cerrado of Central Brazil. Although with the exception of Roupalamontana (which has simple polysepalous flowers arranged in dense cymes) all moth pollinated species in this community have tubular flowers, or a pseudo-tube formed from a single folded petal in Qualeagrandiflora, settling moth flowers (tube less than 15 mm) vs. hawkmoth flowers (tube more than 50 mm) are markedly different in size. Moths visit some 20 woody Cerrado species, but they are probably effective pollinators of only 13 species or ca.14% of the woody taxa studied, and even in these latter species they are often very sparse visitors. Nevertheless, it is notable that moths are pollinators for 21% of the 38 most commonly distributed woody Cerrado species. Moreover, the reproductive efficacy of the studied moth pollinated species was similar to that of species pollinated by other kind of vectors.

Biologia reprodutiva de Psychotria poeppigiana Mull. Arg. (Rubiaceae) em mata de galeria

Psychotria L. (Rubiaceae) is the genus with the most heterostylous species in the angiosperms. The objective of this study is to describe floral biology, phenology, reproductive system, and pollinators of Psychotria poeppigiana Mull. Arg. The terminal inflorescences are capitate with red bracts and yellow flowers, and presented two different morphs: pin and thrum, characterized by hermaphroditic flowers with different lengths of styles and opposed position of the anthers (reciprocal herkogamy). Dimorphism was also observed in the size of anthers, pollen grains and stigmatic surfaces. Controlled pollination revealed self-incompatibility and intramorph-incompatibility at the level of stigma and style. Wasps, butterflies and hummingbirds visited the flowers, especially in early morning. According to the frequency of visits and an efficient transport of pollen between floral morphs, the hummingbird Thalurania furcata was the main pollinator. Little nectar (max. 8µl) was produced during the opening of the flowers (5:00-7:00h). Because of vegetative reproduction the species forms clumps.

Hortia brasiliana Vand. (Rutaceae): polinização por aves Passeriformes no cerrado do sudeste brasileiro

Hortia brasiliana Vand. (Rutaceae) is a common shrub found in cerrado areas of Uberlândia, MG, Brazil. Individuals are 0.5 to 2.0 m high, with rose-coloured and coriaceous flowers, displayed in dense inflorescences. The anthesis occurs along the day or night and can take from 25 min. to 3 hours to complete, according to the temperature. The flower is protandrous and produces an average of 60 µl of nectar, with sugar concentrations ranging from 24 to 32%. The species is self-compatible. Flowers are visited by six Passeriform birds belonging to the Fringillidae, Thraupidae and Mimidae families, considered effective pollinators. This pollination type is new for cerrado vegetation. Birds were observed visiting the flowers to obtain nectar from 4:30 a.m. to 8:30 a.m., when they were sent away by Trigona spinipes bees (Apidae). In order to visit the plant, the birds use the inflorescence as a landing platform, probing 15 to 25 flowers per visit without flight incursion. The permanence period of a bird in a particular plant depended on the arrival of other individuals, and all bird species showed agonistic behaviour when other birds landed on the same plant. Pollination was carried out when the stigma got in contact with body parts in which sticky pollen was adhered to. Among the bees, Trigona spinipes was the most regular visitor, its activity taking place from 8:30 a.m. to 5 p.m. Bees remained in the same inflorescense for a long time performing selfing and geitonogamous pollination. Xylocopa aff. hirsutissima was less common than Trigona spinipes, but due to its behaviour on inflorescences, contacting the stigma and the anther, and its larger size as compared to Trigona, it was considered an additional pollinator. Other visitors (wasps, butterflies, flies, and ants) were considered nectar robbers, occasionally able to perform pollination.

Florística e zonação de espécies vegetais em veredas no Triângulo Mineiro, Brasil

(Floristica e zonacao de especies vegetais em veredas no Triângulo Mineiro, Brasil) A riqueza e a distribuicaodas especies vegetais, a profundidade do lencol freatico e a textura do solo nas zonas de borda, meio e fundoforam determinadas em cinco veredas em Uberlândia e Uberaba, Minas Gerais. A amostragem floristica foidesenvolvida, mensalmente de janeiro de 2002 a janeiro de 2003 em cada vereda. As coletas de solo e asmedidas do lencol freatico foram feitas na parte central de cada zona das veredas. Na amostragem floristicaforam encontradas 436 especies pertencentes a 59 familias e 206 generos. O numero de especies encontradonas seis veredas variou de 146 a 219. Na zona de borda, foram coletadas entre 26 e 87 especies enquanto nazona de meio, em geral, com maior riqueza especifica foram registradas entre 78 e 111 especies. A ordenacaofloristica mostrou variabilidade entre as veredas situadas em solo argiloso e arenoso e entre as zonas commaior e menor umidade do solo. A maior retencao de agua no solo argiloso pode ter interferido na variacao daflora entre as veredas em solo argiloso e arenoso.

Reproductive biology of Geonoma brevispatha Barb. Rodr. (Arecaceae) in floodable riparian forest, in Uberlândia, MG, Brazil

Geonoma brevispatha Barb. Rodr. is a shrub palm with clonal growth and restricted to marshy lands along banks of rivers and streams. The object of this work is to describe its reproductive biology in an area of floodable riparian forest, in Uberlândia, MG. The study was carried out from April 2004 to December 2005. The species flowered from April to August of 2004. The greater production of fruit occurred between October and December. The flowers present a violaceous coloring; they are diclinous, protanderous in the same flower head, emit a strong scent and open about 8:00 in the morning. They are arranged in the rachilla in triads (two lateral staminate flowers and a central pistillate). Only the pistillate flower had nectar. It is smaller than the staminate and its life span is between two and four days and that of the staminate is one day. The rate for pollen viability for flowers in pre-anthesis was 84.3% and 95.9% for recently opened flowers. The stigmatic receptivity occurs as from the bud stage. The average number of flowers per flower head was 2,192.8 ± 1,184.1 staminate and 1,129.5 ± 571.4 pistillate. There was no overlapping between the opening of the staminate and pistillate flowers in the same flower head and neither in the same individual, and so occurring functional dioecy. Apomixis did not occur and therefore the sexual reproduction of the species depends on cross pollination. The main effective pollinators were flies of the Muscidae e Sarcophagidae families. Bees and beetles were considered as occasional pollinators.

Cabralea canjerana subsp. polytricha (Adri. Juss.) Penn. (Meliaceae), uma espécia diótica

The study was carried out at the savanna areas of the Caca e Pesca Itororo Club, Uberlândia, MG, from September 1997 to November 1998. In order to confirm the occurrence of sexual dimorphism, several procedures were undertaken on the supposed dimorphic flowers: pollen viability analysis, measurements of plant height and length of the inflorescence, and pollination experiments to assess the breeding system. Results of pollination treatments and pollen viability analysis revealed the dioecious character of the studied individuals. Sexual morphs were significantly different in their height (F=11.01; P<0.001) and inflorescence length (F=240.82; P<0.005), both being larger on pistillate individuals. Fruit formation was observed only in cross¾pollinated treatments between pistillate and staminate individuals (except one case among 900 trials). The occurrence of fruits naturally formed on male phenotypes indicates that the evolutionary process towards dioecy on this species is still not concluded. Pollination is performed by Polistes wasps and Xylocopa and Exomalopsis bees.

Sistema sexual e biologia floral de Pouteria ramiflora e P. torta (Sapotaceae)

Pouteria ramiflora and P. torta are tree species sympatric in the Cerrado and were studied in the Natural Reserve of Clube Caca e Pesca Itororo (Uberlândia-MG) in order to compare various aspects of their reproductive biology. The phenophases were evaluated weekly and their intensity was quantified. The floral biology, breeding system, sexual system and floral visitors were studied in the field and/or laboratory. In both species, leaf fall occurred in the end of the dry season, leaf flushing between the dry and the rainy season, flowering in the dry season and fruit maturation during the rainy season. They have tubular small greenish flowers, with small amounts of nectar and high pollen viability. They are self-sterile, non-agamospermic and had low fruiting success from natural pollination. P. torta is a hermaphrodite species, with protogynous and hercogamous flowers, while P. ramiflora is morphologically gynomonoecious but functionally unisexual. The apparently low pollen flow and the abortion of young fruits resulted in low fruit set from natural pollinations. Both species are visited by several small insects, including butterflies, moths, flies and bees.