Pollinium, or plural pollinia, is a coherent mass of pollen grains.

They are the product of only one anther, but are transferred, during pollination, as a single unit. This is regularly seen in various plants, such as orchids and some species of the milkweed family Asclepiadaceae.

Orchid genera have mealy pollinia. These are tapering into a caudicle (stalk), attached to the sticky viscidium. They extend into the middle section of the column.

Most orchids have waxy pollinia. These are connected to one or two elongate stipes, which in turn are attached to the viscidium.

The combination of pollinia, caudicles, stipes and viscidium form the pollinarium.