Real and feed pollen of Lagerstroemia indica: ecophysiological differences.

Lagerstroemia indica is heterantheric, its flowers bear- ing two kinds of stamens: six peripheral stamens with long, curved filaments and large anthers producing blue-green pol- len, capable of emitting pollen tubes and fertilizing ovules; or a central tuft of 35 ± 40 smaller anthers producing yellow feed pollen that does not germinate and is collected by insects, mainly bees. The two types of pollen differ in volume, number of pores, pore intine protrusion, wall structure, pollenkitt quali- ty, hydration state, viability at anthesis, longevity and mono- and disaccharide composition. Although total sugar concen- trations (glucose, fructose and sucrose) are the same in both types, relative concentrations are different, arealo pollen being sucrose-rich (S / [G + F] = 1.2) and feed pollen glucose±fructose- rich (S / [G + F] = 0.3). A lower degree of dehydration, pore intine protrusion and higher monosaccharide content could make feed pollen more digestible for pollinators. On the other hand, the cytological features of arealo pollen (high dehydration, higher sucrose content) points to longer viability and reproductive function.