Alder is monoecious which means that both male and female flowers are found on the same tree. The male flowers are the yellow-y pendulous ones and the female ones are like little cones. Our alder tree is still quite small but it's full of catkins so it must like it's position in the boggy bit behind the pond.
I believe Joanne@gardencat posted a similar picture a few weeks ago.
Yes, only I didn’t know what that tree was until someone identified it for me. The only other plant I’m familiar with that has such different male/female flowers is a hops vine. But with hops the male and female are on different plants.
Most interesting. I love the tiny flowers ...