Island NatureExploring nature on Vancouver Island, British Columbia

Pollen is in the Air

Red Alder (Alnus rubra) begins to produce pollen as early as late February on Vancouver Island.

When my husband starts sneezing and snuffling, I know that allergy season has arrived. Here on the coast, pollen related allergies can start in late February and continue through to September. To better understand my husband’s suffering I went to the source, the pollen itself. Most of us are familiar with pollen as the yellow dust that smears our car windshields, or forms a film over spring-shower puddles.

Pollen producing trees, shrubs, flowers and grass are all around us. Pollen, which is always male, is a critical part of plant reproduction. A single pollen grain is actually a male reproductive unit, which scientists call a “male gametophyte”. About three cells large, a single grain of pollen is visible only with a microscope. The familiar yellow dust is made of millions of individual grains. Through the spring we live and breathe pollen, which gets into our hair, clothing and nostrils.

The male catkins of Red Alder (Alnus rubra).

Trees are the culprits of most pollen. The first wave comes from red alder, which starts in late February and peaks in mid-March. Red alder is a fast growing leafy tree with red inner bark. Alders have clusters of separate male and female catkins on the same tree. Male catkins are narrow and drooping and are 10-15 cm long at flowering time. Each catkin is packed with miniature male flowers producing thousands of pollen grains. Catkins that have fallen on the ground often have a yellow halo of pollen around them. Spring female catkins are smaller, greenish and less noticeable.

Alders rely on wind for pollen dispersal. The pollen drifts through the neighbouring trees and lucky grains land on the female catkins. This is a hit and miss process so a lot of pollen goes to waste, which is why red alder produces a tonne of the stuff. By the fall, the mature female seed catkins become brown and woody, and each contains 50 to 100 seeds.

Read more about pollen allergies.

Mar 9, 2010 | by Jocie Ingram | Read | Field Notes