Floral biology of Hedychium coronarium Koen. (Zingiberaceae).
The floral biology of H. coronarium, an introduced species that is naturalized in Brazil, was investigated between November 2003 and July 2004. The species occurs in swamps in large areas of the country, and along roadsides in the municipality of Teresópolis, Rio de Janeiro. The flowers of H. coronarium are white, zygomorphic, hermaphroditic and nectariferous. This species exhibits nocturnal anthesis and emits a strong odour that can spread at long distances. The staminodes are a "unit of attraction" for floral visitors. The androecium is composed of a sole fertile stamen with pollen grains. The stigma is green, wet, concave and surrounded by uniform hairs. The species is self-incompatible, presenting low rates of natural fruit set. The flowers of H. coronarium are important nectar and pollen sources for the insects that visit them. Flowering follows an annual pattern, shows asynchrony in the population level, and lasts from January until April. Fruiting occurs from March to May.