Alder in bloom. Now a common sight in February.

On the lakeshore, a smell of springtime mud and wet leaves. Soil microbes are getting a boost from the unseasonably warm air and our noses are soaked in their festivities, an aroma-pulse of decomposition.

I push forefinger against thumb, then flick, I tap an alder catkin. A cloud of lime-yellow pollen drifts down to the lake water.

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Smooth alder (also called hazel alder, Alnus serrulata)

Alders are monoecious, that is they have separate male and female flowers on the same plant. The male flowers mature before the females, preventing self-pollination.

Male flowers hang in pendulous catkins. They are furry, soft, floppy, cute. Like kittens, hence the name. From 16th century Dutchkatteken, a little cat.

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Female flowers just before they mature and receive pollen.

Female flowers several days later. Their sticky surfaces are now covered by captured pollen.

Female flowers several days later. Their sticky surfaces are now covered by captured pollen.

 

Later in the year the female flowers will swell and harden into small cone-like strobili. These look like cones, but alder is a flowering plant, an angiosperm not a cone-bearing gymnosperm like a pine.

Last year's strobili, their seeds now either shed into the wind or stolen by birds.

Last year’s strobili, their seeds now either shed into the wind or stolen by birds.

A little early for flowering? Not any more. Plants are shifting their bloom and bud-break earlier as the climate warms. For example, a study in the Washington DC area found that over the last 30 years of the 20th century, alder moved its blooming date 11 days earlier. Most species are following suit, but not all at the same rate. Non-native species like privet, bittersweet, and multi-flora rose are less tied to native seasonal rhythms and so are better able to exploit the early springtime warmth.