Pollen development, pollenkitt production and the occurrence of protruding oncus in Garcinia dulcis (Roxb.) Kurz (Clusiaceae)

Abstract

Garcinia dulcis (Roxb.) Kurz is a medicinal plant having potential as a source of medicinal ingredients, yet details of its reproductive biology, especially palynological features, remain largely unresearched. Therefore, a detailed description of pollen development and morphology, and pollenkitt production of G. dulcis, based on both light and electron microscopic analysis, was undertaken. The results showed that G. dulcis underwent sequential anther and pollen development with a high production of pollenkitt. Pollenkitt secreted from tapetum degradation was released early into the locular cavity (at the microspore tetrad stage). The occurrences of intinous protrusion (protruding oncus) at pollen aperture and the precocious pollenkitt production were suggested as adaptive features of G. dulcis to assist its biotic pollination, according to its smooth pollen surface. The results obtained provide new insights into the significant palynological traits that would provide baseline data for further research on G. dulcis.