Hazelnuts, Catkins, Tree flowers, oh my!

the bloom watch has begun

After writing last week’s newsletter on Skunk Cabbage, I realized that many of my favourite spring wildflowers are some of the most unrecognizable, the most demure. I think it’s because often these are the first subtle signs of spring, kicking off the dusky leaf duff, bursting from twig tip, slinking mysteriously out of swollen buds, just a brief snap of colour against brown and grey and there’s something truly exciting in that. In the way they sort of take a big risk to bloom on the edge of two seasons and I find myself both in awe and holding my breath, hoping for their success and also trusting the millennia of ecological knowledge they have written into their DNA that tells them it’s ok. You certainly don’t want to be driving anywhere near me on the backroads these days, my eyes to the sky hunting for fat Cottonwood buds and glorying in the Red Maples fully abloom. March is the month of looking up and it’s high in the tree branches where the first and strangest and most unassuming spring wildflowers are often to be found.

Hark! Hazelnut flowers emerging! I am obsessed with these blossoms. They are actually clusters of flowers called “catkins,” with separate “male” and “female” structures, more on this below!

Ok so first, let’s talk about why tree flowers are so weird. While some trees have flowers that look positively floral—Rose family trees are a good example, apples and cherries and peaches, etc.—most do not. Those trees bloom later and their pollinators are the lovely things one would expect, bees and birds and butterflies and the like. But it’s in the early days of spring, like now, when most of our other trees bloom, when bees and butterflies are a little less reliable, but wind is a constant. So, while some of them still have live pollinator visitors (Red Maples are often the first pollen flush for bees in our parts), many of our trees are wind-pollinated and this is why they have quite odd-looking and unexpected flowers that are designed for the wind.

“Female” or pistillate Red Maple flowers—the little pink worms poking out at the pistils, the seed-producing part of the flower.

Plants that are wind-pollinated often have separate “male” and “female” flowers. I put these in quotations because I have personal issues with this wording, but basically it means that some flowers have stamen, which produce pollen, and some flowers have pistils, which produce seeds/fruit. The wind blows the pollen from the stamen-bearing blossoms to the pistil-bearing ones and the flowers grow in a way that facilitates this. Sometimes a tree has both “male” and “female” on one tree—this is called monoecious— and other times they exist on separate trees—dioecious—which makes one whole tree either “male” or “female.” Red Maples are what’s called polygamo-dioecious, which means, basically, that it’s pretty random—some are all “female”, some are all “male,” and many have both types together.

Stamen protruding from a “male” Red Maple flower

Many of our early spring-blooming trees have floral structures called “catkins” or “aments”—Cottonwoods, Birches, Alders, Hazelnuts, Willows, to name a few. Catkins are actually clusters of many flowers, also distinguished by sex, with separate clusters for the staminate and pistillate ones. Some of them are monoecious, like Hazelnuts, some of them dioecious, like Willows. The “male” aments often hang down and look a bit like worms, while the female ones often sit smaller and upright and end up having a more cone-like look, but of course that’s not across the board. Female Cottonwood aments, for example, also dangle like their male counterparts and look very much like strange furry, pink caterpillars when strewn across the forest floor. Willow aments don’t really hang at all and both have a similar growing pattern.

Staminate, "male" Willow aments on the left, and pistillate "female" Willow aments on the right. Male flowers are often more yellow because of the presence of pollen!

The female flowers on the Hazelnut look a bit more like a small bright pink tassel emerging from a bud tip, while the male flowers are structured in the classic catkin formation, only just opening here in this photo. Hazelnut is monoecious, with both residing on the same plant.

Tree flowers are downright funky and, like Skunk Cabbages, they are one of my favourites to scope out in these early spring days when not much else is growing. They allude to the mystery and complexity of the natural world, the chaos, the order, the fragility and yet also the strength. From these tiny blossoms enormous giants grow, all on the will of the wind. How’s that for perspective? A few more tree flower photos with brief captions below.

Staminate/male Black Birch catkins

Elm flowers, just opening. These flowers, like the Red Maples, are not catkins but, unlike them, have both reproductive parts. This is called “hermaphroditic” or “bisexual,” sometimes even referred to as “perfect,” so a tree is neither male nor female. They are still wind-pollinated and the female parts often mature faster than the male, which reduces the chance of self-fertilization.

Male cottonwood catkins in early emergence. Like Willows they are often hairy or fuzzy at first and very much look like caterpillars to me.

White Ash flowers, these trees bloom a little later, but the set-up is the same! They are dioecious, so with separate male and female flowers on separate male or female trees. This tree is female/pistillate/seed-producing.

Thanks for exploring with me, I hope this is helpful and interesting! Keep your eyes peeled for tumbling tree flowers and lift your eyes to the sky these days—everything is starting to happen. And if you’d like one last opportunity to delve into tree botany with me, the last session of the Winter Botany Intensive is this Sunday 3/17 from 1-4. Email and I’ll send the details. I promise we’ll see so much.

lots of love from this big tree nerd

x hannah