Thursday, May 8, 2014

My Tree is just a Late-Bloomer

Trees are uncommon in the Laramie Basin; our native vegetation is mostly grass and shrubs.  But all along the Laramie River are gallery forests of cottonwoods, so when it came time to pick a tree to follow, that's what I chose.  My cottonwood grows directly across the river from Rich’s bench, where I like to sit and watch the evening progress.
Memorial benches have been strategically placed along the Laramie River.  This one honors Rich Koschnitzki.
I know this tree is a cottonwood and probably a narrowleaf cottonwood, but I’ve been waiting for spring and leaves before making a decision.  Now it’s May and there are still no leaves!  If you’re wondering about the first photo -- it’s fake.  About a month ago I clipped a few bare branchlets from my tree and put them in a jar with water.  It wasn’t long before young leaves emerged.
Several weeks ago I noticed that some buds on some cottonwoods were very plump, but unfortunately not on my tree.
The cottonwood on the right has fat buds and even young catkins; mine (center) does not.
I clipped a few branchlets from the tree on the right above and took them home.  Leaf tips soon emerged from the slender buds and out of the plump ones came female catkins (flower clusters).
Cottonwood flowers aren’t much to look at.  They’re tiny and have no petals.  But they do have reproductive structures and that's what counts.  A female cottonwood flower is simply a pistil sitting on a cupped disc.  Seeds will develop in the ovary after fertilization.
Female cottonwood flowers; the one on the right has the floral bract removed (Kohler's Medicinal Plants).
If you click on the image below, you'll see green pistils sitting on pale green discs.  Their stigmas are the yellowish structures at the tip.  Scale is in centimeters.
Then just a few days ago I noticed that my tree had two kinds of buds, including plump ones (below).  This was great news!  I wanted to collect some of course, but they were all out of reach.
Yesterday I found a long stick on the ground by the tree.  I pushed through the willows to where I could hook and pull down a branch and get a few plump buds.  There were catkins peeking out of them.  What do you think ... guys or gals?
A leaf bud and two flower buds from my cottonwood tree.
Cottonwoods have male and female flowers on different trees (dioecious).  Since the female trees were already blooming, I was tempted to think the plump buds on my tree would produce male catkins.  But I’ve learned not to jump to conclusions.  Plants have fooled me before!

I was right to be cautious.  When I was photographing cottonwood parts, I noticed that catkins were emerging from the plump buds I had collected just an hour earlier.  So I put them by a window and checked back in the afternoon.  They had lengthened even more.  I peeked behind the floral bracts with a 10x hand-lens and found ...
... little green pistils sitting on cupped discs.  Turns out my tree is female too, but she’s a late-bloomer.  So where are the guys?  I don't know, haven't seen any yet.  Maybe I'll be able to answer that question next month.

 There's a gallery forest in the kitchen!
Many thanks to Lucy for getting us going on these adventures.  Check out the latest news about our trees.


  1. Beautiful photos, Hollis. I especially like the one with the bench in the foreground. I don't think I've ever heard of this tree - thanks for the introduction.

    1. Thanks, Tim. I was really tired that evening but when the sun peeked out below the clouds just before sunset, I managed to hustle down to the river anyway ... and found what I needed. Hope things are going better, it's always nice to have you around in the blogosphere :-)

  2. I was specially impressed by the photos this time too - and was wondering if you have a new camera. It's like a detective story. Looking forward to the next episode. (Bet real detectives would like a way of fast-forwarding evidence as you have with the twigs in water.)

    1. thanks, Lucy. Not a new camera but a "new" macro lens. and not even that ... rather a neglected not-so-new lens! I need to use it more, it's really nice. Also good for medium-range shots.