The Collaborative International Dictionary
Pollen \Pol"len\, n. [L. pollen fine flour, fine dust; cf. Gr. ?]
Fine bran or flour. [Obs.]
--Bailey.-
(Bot.) The fecundating dustlike cells of the anthers of flowers. See Flower, and Illust. of Filament.
Pollen grain (Bot.), a particle or call of pollen.
Pollen mass, a pollinium.
--Gray.Pollen sac, a compartment of an anther containing pollen, -- usually there are four in each anther.
Pollen tube, a slender tube which issues from the pollen grain on its contact with the stigma, which it penetrates, thus conveying, it is supposed, the fecundating matter of the grain to the ovule.
Wiktionary
n. (context botany English) A single male reproductive particle of which the pollen of a plant consists.
Usage examples of "pollen grain".
As the pollen tube grows the vegetative cell remains in the pollen grain while the generative cell enters the pollen tube and migrates toward the ovule.
Astron felt his eyes stiffly glance down at the pollen grain at Palodad's feet, a small shred of puzzlement tugging at the muscles in his face.
Just prior to dehiscence, the pollen nucleus divides to produce a small repro- ductive cell accompanied by a large vegeta- tive cell, both of which are contained within the mature pollen grain.
And when a pollen grain lands on a pistil and joins with the ovule prepared in the ovary, the two components are united again.
I was not falling but floating, and I saw that a deeper reality underlay the world of things, a pulsing matrix in which all boundaries were illusory, where the pollen grain was not distinct from the wind, where matter and energy moved in an eternal dance, and life and death were but changing states of both.
Some didn't even look like the same genus, like the ones that grew in thick mats of entwined bushes or the pollen grain that had just been on the screen.