Pollination ecology of Rhynchosia cana (Willd.) DC. (Fabaceae), an erect sub-shrub, in peninsular India

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A.J. Solomon Raju
K. Venkata Ramana


Rhynchosia cana is a perennial erect sub-shrub.  It flowers during November-January with peak flowering in December.  The flowers are hermaphroditic, nectariferous, self-compatible and display explosive pollination mechanism adapted for pollination by bees.  They do not fruit through autonomous selfing, but rather through manipulated selfing, geitonogamy and xenogamy mediated principally by bees and occasionally by lycaenid butterflies.  In the localities of this herb, weeds such as Hyptis suaveolens (Lamiaceae) and Chromolaena odorata (Asteraceae) show luxuriant growth and flower simultaneously, and their intense flowering and high flower density ensures that most flower-visiting insects visit their flowers. In this situation only two bee species, Nomia and Anthidium exhibited fidelity to R. cana flowers.  Un-tripped flowers fall off while tripped ones set fruit.  In open-pollinations, fruit set was 81% and seed set was 54%.  Seed dispersal occurs by explosive pod dehiscence.  Perennial root stock resurrects back to life and restarts its reproductive cycle during the rainy season.  Seeds also germinate at the same time but their continued growth is subject to the availability of soil moisture content.  This study suggests that R. cana is unable to compete with the co-flowering weed species for pollinators, and also has regeneration constraints due to nutrient-deficient rocky habitats with prolific growth of weeds.

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Author Biographies

A.J. Solomon Raju, Department of Environmental Sciences, Andhra University, Waltair Junction, Visakhapatnam, Andhra Pradesh 530003, India

Prof. A.J. SOLOMON RAJU is the Chairman, Board of Studies in the Department of Environmental Sciences & Department of Microbiology, Andhra University, Visakhapatnam. He is the recipient of several national and international awards. He has more than 300 research papers in international and national Journals.  He is on the editorial board of several international journals. He is presently working on keystone and endemic species of Eastern Ghats with financial support from DST and UGC. He visited USA, Canada, UK, Spain, Brazil, Paraguay, Mexico, Italy, Malaysia, Thailand, Ethiopia, Tanzania, Hong Kong and China.

K. Venkata Ramana, Department of Botany, Andhra University, Waltair Junction, Visakhapatnam, Andhra Pradesh 530003, India

Dr. K. Venkata Ramana is currently working as DST SERB Young Scientist in the Department of Botany, Andhra University, Visakhapatnam.  He has published more than twenty papers in international and national journals.  


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