Flower morphology, nectar features, and hummingbird visitation to Palicourea crocea (Rubiaceae) in the Upper Paraná River floodplain, Brazil

Luiz Dos Anjos,Luciana B Mendonça

doi:10.1590/s0001-37652006000100006

Abstract

We investigated flower morphology, nectar features, and hummingbird visitation to Palicourea crocea (Rubiaceae), a common ornithophilous shrub found in the riparian forest understory in the Upper Paraná River floodplain, Brazil. Flowers are distylous and the style-stamen dimorphism is accompanied by other intermorph dimorphisms in corolla length, anther length, and stigma lobe length and form. We did not observe strict reciprocity in the positioning of stigma and anthers between floral morphs. Flowering occurred during the rainy season, October to December. Nectar standing crop per flower was relatively constant throughout the day, which apparently resulted in hummingbirds visiting the plant throughout the day. Energetic content of the nectar in each flower (66.5 J) and that required daily by hummingbird visitors (up to 30 kJ) would oblige visits to hundreds of flowers each day, and thus movements between plants that should result in pollen flow. Three hummingbird species visited the flowers: the Gilded Sapphire (Hylocharis chrysura), the Black-throated Mango (Anthracothorax nigricollis), and the Glittering-bellied Emerald (Chlorostilbon aureoventris). The frequency of hummingbird visitation, nectar features, and the scarcity of other hummingbird-visited flowers in the study area, indicate that P. crocea is an important nectar resource for short-billed hummingbirds in the study site.

Highlights

Rubiaceae include species with floral features related to a variety of pollinating agents including bees, butterflies, moths and hummingbirds (Passos and Sazima 1995, Stone 1996, Machado and Loiola 2000, Wesseling et al 2000)
The floral features of Palicourea crocea probably reflect adaptations to ornithophily (Faegri and van der Pijl 1979, Proctor et al 1996), given that most are similar to those reported for other hummingbird-pollinated Rubiaceae, such as Ferdinandusa speciosa (Castro and Oliveira 2001), Manettia luteo-rubra (Passos and Sazima 1995), Psychotria nuda (Buzato et al 2000), and other species of Palicourea (Sobrevila et al 1983, Ree 1997, Contreras and Ornelas 1999)
The flower size of P. crocea makes nectar accessible to other visitors, such as diurnal moths and butterflies, which perhaps have some participation in pollination

Summary

Introduction

Rubiaceae include species with floral features (morphological and energetic) related to a variety of pollinating agents including bees, butterflies, moths and hummingbirds (Passos and Sazima 1995, Stone 1996, Machado and Loiola 2000, Wesseling et al 2000). Palicourea Aublet is a Neotropical genus (closely related to Psychotria, Taylor 1997) comprising about 200 species of shrubs or small trees that typically occur in the understory and subcanopy of moist to wet forest; most species exhibit floral traits consistent with hummingbird-pollination (Sobrevila et al 1983, Murcia and Feinsinger 1996, Ree 1997, Taylor 1997, Contreras and Ornelas 1999). Other traits commonly associated with heterostyly are self and intra-morph incompatibility and an array of ancillary floral polymorphisms (Barrett 1990). Has been reported in at least 28 angiosperm families (Barrett et al 2000); Rubiaceae is one important family in this respect, containing hundreds of heterostylous species (Barrett et al 2000)

Objectives

Methods

Results

Conclusion