FLOWERING AND POLLINATORS OF THREE DISTYLOUS SPECIES OF Psychotria (Rubiaceae) CO-OCCURRING IN THE BRAZILIAN ATLANTIC FOREST1

Celice Alexandre Silva,Milene Faria Vieira

doi:10.1590/0100-67622015000500001

Celice Alexandre Silva, Milene Faria Vieira

Open Access

https://doi.org/10.1590/0100-67622015000500001

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Journal: Revista Árvore	Publication Date: Oct 1, 2015
Citations: 8	License type: cc-by

Affiliation: Universidade Federal de Viçosa

Abstract

ABSTRACT This study investigates the flowering and pollinators of the floral morphs of three co-occurring distylous species, Psychotria conjugens Müll, P. hastisepala Müll. Arg. and P. sessilis Vell., in two consecutive flowering seasons in an Atlantic Forest fragment in southeastern Brazil. The species have diurnal, cream-colored, tubular, nectariferous flowers and their flowering occurs in the rainy season, from September to April, with little or no overlapping between species, characterizing a staggered flowering. The flowering of the long-and short-styled floral morphs of each species was synchronous, but the number of open flowers per day per morph tended to vary in each flowering season. These numbers were higher in P. sessilis and P. conjugens and, probably, resulted in higher total numbers of visits on its flowers (up to 1084 visits in P. sessilis and 756 in P. conjugens), compared to that observed in P. hastisepala (up to 71). There was a higher frequency of visits to long-styled flowers of all species. The bee Ariphanarthra palpalis was a common pollinator to all species. This bee is native to Brazil, solitary, considered relatively rare and its host plants were unknown. Other native bees (Melipona spp.) also visited the flowers of the Psychotria species. The availability of flowers with similar floral features over eight months, the staggered flowering and common pollinators appear to be part of a strategy to attract floral visitors, minimizing the competition for pollinators and then favoring the legitimate pollination of these plants.

Highlights

The key event in the reproductive biology of angiosperms is flowering (PRIMACK, 1985) and studies on this phenophase are fundamental to understand their regulatory factors (MARTIN-GAJARDO; MORELLATO, 2003)
The flowering of distylous species of Psychotria, analogous to the above description for tropical species, is mostly synchronous, annual and occurs during the rainy season (CASTRO; OLIVEIRA, 2002; COELHO; BARBOSA, 2004). This phenological pattern has been ascribed to the attraction of pollinators, in particular of bees and butterflies, and to obtain greater reproductive success of each floral morph (CASTRO; OLIVEIRA, 2002), which in turn is related to the amount of flowers available, visitation frequency and pollinator behavior (DONALDSON et al, 2002; SAKAI; WRIGHT, 2008)
The present study aims to investigate the flowering and the identity of the pollinators of each floral morphs of Psychotria conjugens Müll

Summary

Introduction

The key event in the reproductive biology of angiosperms is flowering (PRIMACK, 1985) and studies on this phenophase are fundamental to understand their regulatory factors (MARTIN-GAJARDO; MORELLATO, 2003). The number of simultaneously open flowers varies between plant individuals of the same species and the amount of floral resources influences the pattern of pollinator visits (KARRON; MITCHELL, 2012). The flowering of distylous species of Psychotria, analogous to the above description for tropical species, is mostly synchronous, annual and occurs during the rainy season (CASTRO; OLIVEIRA, 2002; COELHO; BARBOSA, 2004). This phenological pattern has been ascribed to the attraction of pollinators, in particular of bees and butterflies, and to obtain greater reproductive success of each floral morph (CASTRO; OLIVEIRA, 2002), which in turn is related to the amount of flowers available, visitation frequency and pollinator behavior (DONALDSON et al, 2002; SAKAI; WRIGHT, 2008).

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