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

Australian Journal of Botany - Tập 56 Số 4 - Trang 363 - 2008
Ludmila M. Pansarin1, Emerson Ricardo Pansarin2, Marlies Sazima1
1Universidade Estadual de Campinas, Instituto de Biologia, Departamento de Botânica, Caixa Postal 6109, 13083-970 Campinas, SP, Brazil.
2Universidade de São Paulo, FFCLRP, Departamento de Biologia, 14040-901, Ribeirão Preto, SP, Brazil.

Tóm tắt

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.

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Thông tin xuất bản

Australian Journal of Botany

Tập 56 Số 4

363

Thông tin tác giả