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The Sound of Cottonwoods (Populus fremontii)

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 I had it all wrong about cottonwoods.

I love the sound of the wind in their leaves,  a sound that mimics flowing water in the way a rainstick echoes rain. I thought they made that sound because they had double-jointed leaves.

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It’s one of those things that stuck in my head – wrong, as it turns out. So when I got next to a cottonwood, and started looking at where the petiole meets the branch, and I couldn’t figure out what makes it different. (The petiole is the part that connects the leaf to the stem. In some plants, like willows, it’s very short. In others, such as cottonwoods, it’s extended.) Since I couldn’t make head or tail out of what I was seeing, I went to my old reliable Sierra Nevada Natural History, and looked it up.

I found the clue under aspen (Populus tremuloides). From its species name, tremuloides, it’s easy to guess what trait is being described. From the genus name (Populus), it’s easy to guess that both aspens and cottonwoods are related to poplars, which have the same trembling leaves.  The reason for that, my Sierra Nevada Natural History told me, is that “the leaves, having vertically flat petioles, quiver in any breeze.”

“Vertically flat petioles, vertically flat petioles,” I muttered to myself, unable to configure vertically flat in my mind. So I went out to look.

 Vertically flat petioles look like this:

 

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 And in action, they look like this:

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The wide flat edge acts like a miniature sail, so that the least breeze causes leaves to move, and gives them that unique sound.It could be that this allows their seeds – little bits of white fluff that give cottonwood its name – to be scattered farther, increasing their tribe. In any case the sound of the poplar family is unlike any other, a restful sound, as if I were listening to a brook made of air.  Some cottonwoods grow straight up, like their poplar relatives, and others branch out into several trunks. Unlike poplars, however, their crowns are broad and flat.

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The bark of the Fremont cottonwood that I was looking at (there are other kinds) is rough and fibrous, a clue to the kind of wood within. A source who knows his firewood told me that it’s next to useless for burning. Since cottonwoods grow only where there’s a high water table, every one of those fibers is filled with water.

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So first you have to really dry them out. Then, when you get the into the stove, they burn quickly and dirtily, without much heat, and leave a lot of ash.  If you’re looking for firewood, best look elsewhere. But if you’re looking for a sign – and a sound – of water, cottonwoods will take you there. 

 

 

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Leaf buds for next year 

{ 15 comments… add one }

  • Town Mouse October 24, 2010, 7:52 pm

    Who knew? Thanks for looking that up for us!

  • Sylvia (England) October 25, 2010, 12:40 am

    Pomona, I brilliant post, so very interesting. I haven’t seen a cottonwood but poplars are quite common here. I love you description “a miniature sail”. My Grandmother used to hate the sound of wind in the poplars that grew across the road from her house – so the sound reminds me of her. I don’t remember them sounding like running water but I will listen next time I see some.

    Best wishes Sylvia (England)

  • Pomona Belvedere October 28, 2010, 11:25 am

    Town Mouse – glad you enjoyed it! I always like finding out thing like this.

    Sylvia, it’s so interesting how sounds evoke memory. Interesting too that your Grandmother had an aversion to this sound and that is why you associate it with her!

  • lostlandscape (James) October 31, 2010, 9:29 pm

    Ah, so that’s why the leaves quiver! Around here, where there are cottonwoods there are sycamores, and for years I’d been paying attention mostly to the sycamores. But the poplars are getting more of my attention these days. At my native plant society’s plant sale they sold out of sycamores quickly but I was pointing out the coolness of these trees to some of the disappointed folks. At the sale cottonwoods alphabetized right next to the sycamores (Platanus). Funny, I thought, since you see them together in the wilds too!

    Thanks for the great post.

  • Pomona Belvedere November 3, 2010, 11:25 am

    James, I like the alphabetical/topographical juxtapositions. Since DNA testing is changing the names of everything, maybe we could make it even more confusing, and insist on species alphabetization by plant community. Should keep botanists at work for decades.

  • Chris Maciel November 11, 2010, 6:18 pm

    Having grown up in the west I always associate cottonwoods with Western movies where they are always shown growing next to the river, of course;
    sometimes being the only tree in sight in ‘them dar hills’. So romantic!
    Now I live where quaking Aspen are common, and they do have a lovely sound in strong wind, a water-rushing-by kind of sound.
    Another nice post!
    Thanks.

  • Brenda December 25, 2010, 3:09 pm

    I’ve got a stand of cottonwoods at the end of the driveway, they grow along the roadside ditch and love all that water. They rain cotton in the summer and I hear the sound of water everytime I walk by. It’s a lovely sound! And since the cotton is pretty far from the house, that’s cool too!

  • AnniesAngels August 11, 2013, 8:34 pm

    I found this blog searching under “the sound of Cottonwood Trees?” They are my favorite lullaby tree sound. Where Pines tend to make a lonely sound, Cotton Woods sound to me like a thousand little fairies applauding… hence they are very ego gratifying when feeling down. When I was little I took naps to the gentle sound of cotton wood trees. So you can imagine my joy in finding the description of “rain sticks” and “water-rushing-by!” There had been a terrible drought in Iowa, following an F 3 tornado. We all thought the cotton wood was dead. This year it has resurrected from the dead, glistening and shiny…all 75 ft tall of it.

  • E January 3, 2014, 8:36 pm

    Thanks for this post! I found it by searching for “sound of wind in cottonwood trees.” My great-grandmother wrote about this sound being one of the first memories of her life, growing up in Oklahoma at an Indian agency in the 1890s. Thank you for sharing your knowledge!

  • wndfrm June 12, 2014, 12:25 pm

    not sure how old this post it, but thanks. on a frequently traveled route to the local grocery store, i make it a point on breezy days to walk by a small grouping of trees in a yard.. due to their gentle rustling! i am a sound artist, and i cannot help but be drawn to these cottonwoods, clapping fairies indeed :) my children helped me acquire a fallen leaf, and after looking up the genus i find i am not the only one to appreciate this distinctive sound. thanks for the investigation!

  • Zachary Royce September 11, 2015, 8:58 am

    I Googled “cottonwood leaves in wind” and your lovely and excellent post provided me exactly the explanation I was looking for.

  • AnniesAngels September 11, 2015, 6:18 pm

    My favorite sound in the world is the clapping of cottonwoods, which not only resemble the sound of water but also distant clapping. Just makes mornings go that much better when

  • Zachary Royce September 19, 2015, 4:49 pm

    After reading your post, and being educated about the flat petiole, I was walking in the local cemetery and saw a white poplar twinkling and whooshing in its distinctive way in the wind. I pulled a leaf off and examined the petiole and played with it in the breeze. I don’t think the twinkling comes from the flat petiole actually catching the wind like a sail, but rather from the structural rigidity of this shape, which bends easily in one plane but not another, like a yardstick. The leaf itself acts like the sail, and the plane of its surface is perpendicular to the “vertically flat” plane of the petiole. Thus, when the wind presses on it, the petiole resists and snaps it back–thus it flutters back and forth under the tension–boi-oi-oingg!

    :)

  • Zachary Royce September 19, 2015, 5:39 pm

    Actually, now that I’ve thought about some more, I don’t think I stated it quite correctly. Whereas most other leaves would be pushed flat in the direction of the wind, so the wind can flow over them without resistance; the rigidity of the flat petiole here holds the leaf up against the wind pressing on it, like a street sign on a post. The leaf then flutters in the wind, because it is held up in the way. It particularly flutters left and right because the wind has more leverage on its sides than it does on the center of the leaf. As the leaf twists in this manner it meets the resistance of the rigid petiole and snaps back. It’s like a sign post in the wind, except imagine the sign mounted to the pole with flexy springs instead of fastened down tight with bolts.

  • Jason Gass July 23, 2016, 7:27 am

    I live in Oklahoma and have been a landscaper and arborist for close to twenty years. During the late summer heat , there are so many cottonwoods dropping their seeds that it looks like fresh powder in Aspen.

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