A pollinium (plural pollinia) is a coherent mass of

pollen Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametop ...

grains in a plant that are the product of only one anther, but are transferred, during pollination, as a single unit. This is regularly seen in plants such as orchids and many species of milkweeds ( Asclepiadoideae). Usage of the term differs: in some orchids two masses of pollen are well attached to one another, but in other orchids there are two halves (with two separate viscidia) each of which is sometimes referred to as a pollinium. Most orchids have waxy pollinia. These are connected to one or two elongate stipes, which in turn are attached to a sticky viscidium, a disc-shaped structure that sticks to a visiting insect. Some orchid genera have mealy pollinia. These are tapering into a caudicle (stalk), attached to the viscidium. They extend into the middle section of the column. The pollinarium is a collective term that means either (1) the complete set of pollinia from all the anthers of a flower, as in Asclepiadoideae, (2) in Asclepiadoideae, a pair of pollinia and the parts that connect them (corpusculum and translator arms), or (3) in orchids, a pair of pollinia with two viscidia and the other connecting parts. Image:Pollinia Phalaenopsis (1).jpg, The waxy pollinia of a ''Phalaenopsis'' Image:Phaleanopsis pollinia.jpg, Pollinia of a '' Phalaenopsis'' orchid Image:Ophrys apifera flower2-der.jpg, Pollinium of '' Ophrys apifera'' File:Eucera cinnamomea with pollinium 1.jpg, Male bee (''Eucera cinnamomea'') with pollinium attached to its head File:Bee on Antelope Horn-April 2015.JPG, Honeybee on antelope horn (''

Asclepias asperula ''Asclepias asperula'', commonly called antelope horns milkweed or spider milkweed, is a species of milkweed native to the Southwestern United States and northern Mexico. Description It is a perennial plant growing to 0.3–0.9 m (1–3 ft) tal ...

'') with pollinia attached to legs File:Xylocopa virginica pollinia closeup.jpg, Pollinia of milkweed (''Asclepias'') on the legs of carpenteer bee ('' Xylocopa virginica'')

References

{{Commons, Pollinium (Orchidaceae) Pollination Plant anatomy Orchid morphology