: pollinia) is a coherent mass of pollen grains in a plant that are the product of only one anther, but are transferred, during pollination, as a single unit.
These are connected to one or two elongate stipes,[clarification needed][3] which in turn are attached to a sticky viscidium, a disc-shaped structure that sticks to a visiting insect.
[1] Milkweed pollinia are housed within a stigma chamber at the bottom of anther slits of its flower.
A pollinating insect often stumbles in such a way that its legs fall down the slits, then pull up the pollinia as it tries to free its legs; the pollinia can be carried to another flower and dropped down the latter's slits to achieve pollination.
However, the insect sometimes fails to retract its legs from the slits and is trapped there until it dies.