Ludmila Mickeliunas Pansarin

Reproductive biology of Cyrtopodium polyphyllum (Orchidaceae): a Cyrtopodiinae pollinated by deceit.

The genus Cyrtopodium comprises about 42 species distributed from southern Florida to northern Argentina. Cyrtopodium polyphyllum occurs on rocks or in sandy soils, in restinga vegetation along the Brazilian coast. It flowers during the wet season and its inflorescences produce a high number of resupinate yellow flowers. Cyrtopodium polyphyllum offers no rewards to its pollinators, but mimics the yellow, reward-producing flowers of nearby growing Stigmaphyllon arenicola (oil) and Crotalaria vitellina (nectar) individuals. Several species of bee visit flowers of C. polyphyllum, but only two species of Centris (Centris tarsata and Centris labrosa) act as pollinators. Visits to flowers of C. polyphyllum were scarce and, as a consequence, low-fruit set was recorded under natural conditions. Such low-fruit production contrasts with the number of fruits each plant bears after manual pollination, suggesting deficient pollen transfer among plants. C. polyphyllum is self-compatible and has a high-fruit set in both manual self- and cross-pollinated flowers. Furthermore, fruits (2%) are formed by self-pollination assisted by rain. This facultative self-pollination mechanism is an important strategy to provide reproductive assurance to C. polyphyllum as rainfall restricts the foraging activity of its pollinating bees. Fruits derived from treatments and under natural conditions had a similar high rate of potentially viable seed. Moreover, these seeds had a low polyembryony rate, which did not exceed 5%. C. polyphyllum acts by deceit involving optical signals and exploits other yellow-flowered species within its habitat by attracting their pollinators. The low capsule production under natural conditions was expected, but its reproductive success is assured through self-pollination by rain and high seed viability.

Facultative autogamy in Cyrtopodium polyphyllum (Orchidaceae) through a rain-assisted pollination mechanism

Cyrtopodium includes ~42 species, among which is Cyrtopodium polyphyllum (Vell.) Pabst ex F. Barros that occurs in a rainforest in south-eastern Brazil. Its non-rewarding flowers, which attract Centridini bees by deceit, are rain-assisted self-pollinated, a phenomenon rarely found in orchids and other plant families. In addition, self-pollination has never been reported in Cyrtopodiinae and data on the pollination of South American orchids are scarce. Flowers were observed at different times of the day, on both sunny and rainy days, to record floral morphology, visitors and the effects of rainfall on flowers. On rainy days, water accumulates on the stigma and dissolves the adhesive substance of the stigmatic surface. A viscous drop thus forms, which contacts the pollinarium. When evaporation makes the viscous drop shrink, the drop moves the pollinarium with the anther onto the stigmatic surface and promotes self-pollination. Fruit set in natural habitat was low, with 2.4% at one study site, where a similar value (2.2%) was recorded in flowers self-pollinated by rain. In C. polyphyllum, facultative self-pollination assisted by rain is thus an important strategy that guarantees fruit set when pollinator’s visits are scarce, which is common in species pollinated by deceit.

The Natural History of Cirrhaea and the Pollination System of Stanhopeinae (Orchidaceae)

Premise of research. The relations between orchids and their pollinators are so specialized that the pollination of some of these flowers depends solely on specific groups of bees. Members of Stanhopeinae are pollinated exclusively by fragrance-collecting male euglossines. Although many studies have documented the pollination biology of various Stanhopeinae, data on the natural history of some genera (e.g., the Brazilian endemic Cirrhaea) are still lacking. In addition, few studies include molecular data on their pollination systems, and the Brazilian representatives of Stanhopeinae are rarely considered in phylogenies. Methodology. We documented the floral and reproductive biology of Cirrhaea through focal observations and experiments. We studied the interaction network between Stanhopeinae and Euglossini by reconstructing the phylogenies of both pollinators and orchids from molecular data. Pivotal results. Cirrhaea species present floral fragrances with different chemical compositions, are self-compatible, and are pollinated by two or more euglossine species. A single species of Cirrhaea can be pollinated by up to three bee species, and a single species of orchid bee can pollinate more than one species of Cirrhaea. Our data show that the relation between Cirrhaea and euglossines is not species specific and that orchids depend unilaterally on bees. Conclusions. The selection pressures of euglossine on flowers have promoted the production of divergent perfume bouquets. Moreover, they have favored the emergence of peculiar flower morphologies that have resulted in particular pollination mechanisms. This close relationship between flower and pollinator reduces pollen loss and promotes isolating mechanisms between sympatric interfertile species. The combination of the phylogeny of Stanhopeinae and Euglossini shows that species-specific relations between the evolution of plants and pollinators are rare.

Reproductive biology of Echinodorus grandiflorus (Alismataceae): evidence of self-sterility in populations of the state of São Paulo

Resumo A biologia floral e reprodutiva de Echinodorus grandiflorus (Cham. & Schltdl.) Micheli foram estudadas em populacoes nativas do interior do estado de Sao Paulo. A especie floresce no verao e suas flores oferecem tanto nectar quanto polen como recurso. O nectar e secretado por nectarios localizados na base dos carpelos marginais, opostos as petalas. Os polinizadores (abelhas sociais e solitarias), no entanto, foram observados coletando apenas polen. As visitas, que podem durar de um a poucos segundos ate mais de um minuto, acontecem desde o momento da abertura das flores (ca. 5:30 h) ate o fenecimento. Cada flor dura cerca de oito horas. Todos os individuos das populacoes produzem apenas flores hermafroditas. A porcentagem de graos de polen viaveis e de 75%. As populacoes estudadas sao autoincompativeis e, como consequencia, polinizadores sao necessarios para transferencia de polen. Em condicoes naturais e a partir das polinizacoes cruzadas realizadas manualmente, todos os receptaculos apresentaram aquenios maduros. Atraves das analises dos tubos polinicos das flores autopolinizadas manualmente, e devido ao fato dos aquenios derivados desse tratamento abortarem cerca de 30 dias a partir das autopolinizacoes, aparentemente, as populacoes de E. grandiflorus estudadas apresentam um mecanismo de auto-esterilidade de acao tardia. Palavras-chave: Alismataceae, auto-compatibilidade, biologia da polinizacao. Abstract The reproductive biology and the pollination of Echinodorus grandiflorus (Cham. & Schltdl.) Micheli were studied in populations native to interior of the State of Sao Paulo, Brazil. This species blossoms in summer and its flowers offer both nectar and pollen as rewards to pollinators. Nectar is produced in nectaries located at the base of the marginal carpels, opposite the petals. However, the effective pollinators (social and solitary bees), were recorded collecting pollen only. Visits, which can last from one or a few seconds to more than one minute, occur during the whole flower lifespan. Each flower opens at about 5:30 a.m. and lasts circa eight hours. All plants in the studied populations produce only hermaphrodite flowers. Percentage of pollen viability is 75%. The studied populations are self-incompatible and, as a consequence, pollinators are needed to transfer pollen among individuals. In natural conditions and after hand cross-pollinations, all receptacles presented mature achenes. Based on the analyses of pollen tube growth from hand self-pollinated flowers, and as a consequence of achenes abortion circa 30 days after self-pollinations, the populations of E. grandiflorus studied apparently presents a mechanism of late-acting self-sterility. Key words: Alismataceae, pollination biology, self-compatibility.

Objectives and justificative

The main object of this book is to present the research and identification of the diversity of orchid species present in one of the last remaining continuous forests in the state of Sao Paulo, the Serra do Japi.

The family Orchidaceae

The family Orchidaceae comprises about 7% of all angiosperms and is considered one of the largest families of this group. The family presents more than 25,000 species, distributed around the world, but showing greatest diversity in tropical regions. A vast number of orchid species occur especially in the Neotropics. Most orchids are epiphytic. Nevertheless, many species are rupiculous, terrestrial, mico-heterothrophic or occur in marshy areas.

The Serra do Japi

The Serra do Japi is one of the last areas of continuous forest in state of Sao Paulo. The region has an area of approximately 354 km2 and covers four municipalities: Cabreūva, Cajamar, Jundiai and Pirapora do Bom Jesus. Due to its location between large centres (Campinas and Sao Paulo) and surrounded as it is by densely populated regions, the Serra do Japi has suffered the effects of severe anthropogenic interference along almost its entire length. As a result, the flora and fauna of the region have undergone changes. Besides anthropogenic changes, leading to differences in vegetation, natural changes have also occurred as a result of differences in soil, moisture and altitude and have contributed to the floristic character of some regions of the Serra do Japi.

Nomenclature and classification

Plant species, as well as animal and fungi, have a Latin name, which follows the binomial system of Linnaeus (Carl von Linne, 1707–1778). The first name refers to the genus (e.g. Cleistes, Bulbophyllum, Constantia and Cattleya). The second name is the specific epithet (e.g. montana, punctatum, cipoensis and loddigesii). The Latin names can be assigned, for example, according to the habitat of the plant (e.g. Cleistes Montana), floral or vegetative character (e.g. Bulbophyllum punctatum), locality where the plant occurs, mainly when it is considered endemic of a region (e.g. Constantia cipoensis), which occur exclusively in the Serra do Cipo (state of Minas Gerais, Brazil). Some plant names are attributed in honour of a particular person (e.g. Cattleya loddigesii), in honour of Joachin Conrad Loddiges. Names of species are always writing in italics and the first letter of the genus is capitalized. The names of species should always be accompanied by the names of their respective authors (e.g. Cattleya loddigesii Lindley, Bulbophyllum punctatum Barbosa Rodrigues). In citations of plant names, authors’s names are often abbreviated according to Brummit & Powell (1992) “Authors of Plant Names” (e.g. Cattleya loddigesii Lindl., Bulbophyllum punctatum Barb. Rodr.).

List of species of orchids occurring in the Serra do Japi

Classification according to Pridgeon et al. (1999–2005). Division in tribes and subtribes follow Dressler (1993)