UNLABELLED: BACKGROUND AND AIMS The extreme complexity of asclepiad flowers (Asclepiadoideae-Apocynaceae) has generated particular interest in the pollination biology of this group of plants especially in the mechanisms involved in the pollination processes. This study compares two South American species, Morrenia odorata and Morrenia brachystephana, with respect to morphology and anatomy of flower structures, dynamic aspects of the pollination mechanism, diversity of visitors and effectiveness of pollinators. METHODS: Floral structure was studied with fresh and fixed flowers following classical techniques. The pollination mechanism was studied by visiting fresh flowers in the laboratory with artificial pollinator body parts created with an eyelash. Morphometric and nectar measurements were also taken. Pollen transfer efficiency in the flowers was calculated by recording the frequency of removed and inserted pollinia. Visitor activity was recorded in the field, and floral visitors were captured for subsequent analysis of pollen loads. Finally, pollinator effectiveness was calculated with an index. KEY RESULTS: The detailed structure of the flowers revealed a complex system of guide rails and chambers precisely arranged in order to achieve effective pollinaria transport. Morrenia odorata is functionally specialized for wasp pollination, and M. brachystephana for wasp and bee pollination. Pollinators transport chains of pollinaria adhered to their mouthparts. CONCLUSIONS: Morrenia odorata and M. brachystephana present differences in the morphology and size of their corona, gynostegium and pollinaria, which explain the differences in details of the functioning of the general pollination mechanism. Pollination is performed by different groups of highly effective pollinators. Morrenia species are specialized for pollination mainly by several species of wasps, a specialized pollination which has been poorly studied. In particular, pompilid wasps are reported as important pollinators in other regions outside South Africa. A putative new function of nectar in asclepiads is presented, as it would be contributing to the pollination mechanism.
UNLABELLED: BACKGROUND AND AIMS The extreme complexity of asclepiad flowers (Asclepiadoideae-Apocynaceae) has generated particular interest in the pollination biology of this group of plants especially in the mechanisms involved in the pollination processes. This study compares two South American species, Morrenia odorata and Morrenia brachystephana, with respect to morphology and anatomy of flower structures, dynamic aspects of the pollination mechanism, diversity of visitors and effectiveness of pollinators. METHODS: Floral structure was studied with fresh and fixed flowers following classical techniques. The pollination mechanism was studied by visiting fresh flowers in the laboratory with artificial pollinator body parts created with an eyelash. Morphometric and nectar measurements were also taken. Pollen transfer efficiency in the flowers was calculated by recording the frequency of removed and inserted pollinia. Visitor activity was recorded in the field, and floral visitors were captured for subsequent analysis of pollen loads. Finally, pollinator effectiveness was calculated with an index. KEY RESULTS: The detailed structure of the flowers revealed a complex system of guide rails and chambers precisely arranged in order to achieve effective pollinaria transport. Morrenia odorata is functionally specialized for wasp pollination, and M. brachystephana for wasp and bee pollination. Pollinators transport chains of pollinaria adhered to their mouthparts. CONCLUSIONS:Morrenia odorata and M. brachystephana present differences in the morphology and size of their corona, gynostegium and pollinaria, which explain the differences in details of the functioning of the general pollination mechanism. Pollination is performed by different groups of highly effective pollinators. Morrenia species are specialized for pollination mainly by several species of wasps, a specialized pollination which has been poorly studied. In particular, pompilid wasps are reported as important pollinators in other regions outside South Africa. A putative new function of nectar in asclepiads is presented, as it would be contributing to the pollination mechanism.
Authors: Jeff Ollerton; Sigrid Liede-Schumann; Mary E Endress; Ulrich Meve; André Rodrigo Rech; Adam Shuttleworth; Héctor A Keller; Mark Fishbein; Leonardo O Alvarado-Cárdenas; Felipe W Amorim; Peter Bernhardt; Ferhat Celep; Yolanda Chirango; Fidel Chiriboga-Arroyo; Laure Civeyrel; Andrea Cocucci; Louise Cranmer; Inara Carolina da Silva-Batista; Linde de Jager; Mariana Scaramussa Deprá; Arthur Domingos-Melo; Courtney Dvorsky; Kayna Agostini; Leandro Freitas; Maria Cristina Gaglianone; Leo Galetto; Mike Gilbert; Ixchel González-Ramírez; Pablo Gorostiague; David Goyder; Leandro Hachuy-Filho; Annemarie Heiduk; Aaron Howard; Gretchen Ionta; Sofia C Islas-Hernández; Steven D Johnson; Lize Joubert; Christopher N Kaiser-Bunbury; Susan Kephart; Aroonrat Kidyoo; Suzanne Koptur; Cristiana Koschnitzke; Ellen Lamborn; Tatyana Livshultz; Isabel Cristina Machado; Salvador Marino; Lumi Mema; Ko Mochizuki; Leonor Patrícia Cerdeira Morellato; Chediel K Mrisha; Evalyne W Muiruri; Naoyuki Nakahama; Viviany Teixeira Nascimento; Clive Nuttman; Paulo Eugenio Oliveira; Craig I Peter; Sachin Punekar; Nicole Rafferty; Alessandro Rapini; Zong-Xin Ren; Claudia I Rodríguez-Flores; Liliana Rosero; Shoko Sakai; Marlies Sazima; Sandy-Lynn Steenhuisen; Ching-Wen Tan; Carolina Torres; Kristian Trøjelsgaard; Atushi Ushimaru; Milene Faria Vieira; Ana Pía Wiemer; Tadashi Yamashiro; Tarcila Nadia; Joel Queiroz; Zelma Quirino Journal: Ann Bot Date: 2019-01-23 Impact factor: 4.357