Pear blossom pollen and anthers

Pear anthers changes from a plump red/purple to black over a couple of days as it releases pollen( dehisces) and then oxidizes, dries and shrivels. The colour is caused by anthocyanins in the cells of the anther including its epidermis. The pollen that is released is actually yellow.

 

If the flower has been pollinated by bees the flower will then progress to fruit set.

 

A pear anther is part of the flower structure as shown here in cross section.

Photo credit Yearbook of the United States Department of Agriculture Washington, DC: Government Printing Office, 1898

An anther is a bilobed structure with four pollen sacs containing pollen grains. Pollen release occurs as the anther matures and splits open along its length laterally between the 2 sacs or dehisces which occurs after after the flower's stigma becomes receptive for self fertilising species.

 
The pollen sacs are where pollen grains are produced and stored.  Each pollen grain is an encapsulated single male gamete that develops from a diploid microspore mother cell that undergo meiosis to produce microspores, which then mature into pollen grains. The energy and nutrients for this supplied by the tapetum layer around each sac which is supplied by the vascular pedicle.