March 9, 2013
Pacific Northwest
It's spring! The sun peeks out, birds are singing...and, sigh...my head is a bit plugged up today. Windblown pollen is everywhere in this light dry breeze. Even if my own immune system is overreacting when I breathe it in (and more so every year it seems) I can't help but respect the scale of reproductive hopefulness all this pollen represents.
The very earliest pollen producers in this area are members of the Birch family, Betulaceae, most notably Red Alder (Alnus rubra).
These trees produce separate male and female flowers on the same tree, called catkins (the word comes from the Dutch katteken, meaning kitten...ripe catkins do look like a kitten's tail).
On Feb 13, they looked like this (left), and today they look like this (right)
Some are more ripe, like the ones below, giving a reddish tinge to the leafless tree. Leafless is good right now (for the tree) - it means windblown pollen can travel long distances unimpeded. Leafing out marks the end of pollination season.
Each long male catkin has about a hundred flowers, each with 4 stamens usually, and every stamen produces thousands of pollen grains. The tree is covered with catkins and there are trees all over the neighborhood. I don't even want to do the math. Each grain of this multitude is hoping to land on a female catkin, of a different tree (since the male and female ripeness timing is offset for a given tree). The female catkins are the small ones to the left in the photo above.
If by some chance the timing and location is right, fertilization occurs, the female flower grows a conelike fruit about the seeds, which are wind-dispersed later in the year. These brown "cones" stay on the tree for years.
Native Hazelnut catkins (
Corylus cornuta, another member of the Birch family) actually ripen earlier. Here's Hazelnut on Feb 13 (left) and March 9 (right).
The female flower ends in that bright pink feathery structure on the end of this branch.
I decided to put my photo-microscope to use (I usually use it to track plankton populations in the bays). On the left is alder pollen (400x), on the right is hazelnut pollen. There were fewer Hazelnut grains, and in worse shape than the Alder - that species is finishing up its pollination season.
Alder pollen has 5 germination pores while Hazelnut has 3. There's just barely enough resolution here to see that in these pics.
Just for fun, while I had the scope out, I shook the flowers of two non-wind-pollinated plants onto slides to see their pollen. Right now, Salmonberry (Rubus spectabilis) is in full flower (left), and there were a couple of very early outlier Dewberry, aka Trailing Blackberry, flowers (Rubus ursinus), right. There are very few insects out and about right now, but the resident Anna's Hummingirds are loving the Salmonberry.
Salmonberry pollen
had distinctive midline ridging. I expected to see that from Dewberry too, since they are closely related. But alas, all I saw in that sample was....Alder pollen. Wasted, from Alder's point of view, but with the unimaginably vast numbers they produce, to be expected. But all that "wasted" pollen is a great source of food for many insects and other critters (plus it's very handy to people in forensic and archeological problem-solving).
How's spring springing in your neighborhood? Changes or developments? What's coming or going? Drop a note in the Bucket with your observations!
Update: March 10
Drizzle has replaced the sun of yesterday. Airborne pollen has been washed out of the air, and my symptoms are much improved. Yay for drizzle in Alder pollen season. Still to come is Pine pollen season, when I get such big drifts of the stuff I have to scrape it off my windshield to see.