Friday, April 02, 2010

A Telling Time for Cottonwoods

One of my simple pleasures in spring is sexing the cottonwoods I see as I drive. (Yes, I know I'm weird.) Only female cottonwoods produce cotton, so it can be useful to figure out if a tree is a male or a female...and it's VERY easy to tell (if the tree is big enough) at this time of year.

You see, cottonwoods are in bloom right now and cottonwoods, like people, come in male and female models. Male flowers are colored red, while female flowers are yellowish green. Cottonwoods don't start blooming until they are at least 15-20' tall, and they tend to bloom only in the upper parts of their canopies, so most people don't notice cottonwood blossoms at all. Once you know what you're looking for, though, they are easy to recognize.

One of my favorite finds is multitrunked cottonwood trees where part of the tree is male and part of the tree is female. These grow where several seeds sprouted in close proximity to each other, giving the appearance of a single plant. In this photo of an example east of Clearwater, you can tell there are two trees, but the canopy melds together into one whole. The male tree is on the left and the female tree is on the right.

If you watch the ground under cottonwood trees at this time of year, you can see the blossoms up close after they fall from the tree - especially the males. Here is a bloom that I found just this morning on a walkabout in the back yard. It's about 2 1/2" or 3" in length overall.

I love cottonwood trees. Their shining, dancing leaves rustle in the slightest breeze and seem to cool me during the summertime with both their motion and their gentle whispers. The trees grow rapidly and are wonderful wildlife habitat, attaining a stature in the landscape that really satisfies me here on the prairie.

Cottonwoods have received a lot of bad press lately, though. My personal opinion is that the quest for a "cottonless" cottonwood is greatly to blame. Obviously, for a cottonless cottonwood, all you need is a male tree. The current crop of selected cultivars, though, does not seem to do well in the Wichita area past about 15 years of age...which means that just as the trees are looking like true trees, they get infested with cottonwood borers and die.

My solution? Learn to live with the cotton. It's really quite beautiful during its season, and several bird species use it to line their nests. If you accept that cotton is a part of life on the prairie, you can simply transplant seedling cottonwood trees with local genetics and enjoy this graceful, giving tree for many years. Who knows? In 15 years, you might even discover that you got a naturally cottonless male!


~Gardener on Sherlock Street said...

I love cottonwood trees. While I knew on the females produced the cotton, I never knew the males and females had different colored blooms. Thanks for the info.

~Gardener on Sherlock Street said...

Ever since I read your blog about the male and female cottonwoods blooming different colors, I've been looking at the trees closer going "boy, boy, girl, boy..." :-)

David in Kansas said...

Good information! Now I know my cottonwood tree is a boy. I wondered why mine did not produce cotton. My neighbor's produce enough cotton for the whole neighborhood.
I heard that the natives called it the Rustling Tree or the Talking Tree because of the great sound they make in the Summer when the wind runs through their canopies.
I also heard that the end may be coming for Cottonwoods in Kansas because of the warmer than usual Fall temperatures. I haven't checked this last piece of news out though.

Anonymous said...

Thank you for your comprehensive write-up :-) As for my 26 ft tall 3 year old cottonwood planted in an old tomato garden I can finally say with certainty "It's a boy"!

Unknown said...

We bought a 17 year old home in Utah twenty three years ago. The back yard acre is blessed with a giant cottonwood that out-grew the playhouse we carefully built around it when our 5 boys were young. Our daughter's wedding reception photos were taken with this beautiful tree in the background. We have wonderful memories with this tree. However, our neighbor has tried to sue us to remove it. He and his wife hate the cotton. It is the last one in the neighborhood to throw and it is convenient for them to blame April thru June's cotton season on us. They do not speak to us - only in sneers and gossip talk. Everything mean thing they do (sweeping their driveway trash onto our drive way and being mean mouths) we feel a little flowing cotton pays them back generously! How grateful we are for a tree that does our bidding for us!

Gaia Gardener: said...

So sorry that your beautiful cottonwood tree has been the focus of attack by what sounds like a thoroughly unpleasant pair of neighbors. My condolences on living next door to these unhappy individuals, but kudos to you for standing strong and for celebrating the wonderful tree that you have the privilege of caring for. What a treasure you have in your yard!

Anonymous said...

We have 5 young cottonwoods on our property. It seems like 3 and 2 is the split between male female although they are too young for flowers. Two always leaf sooner than the others. Do male or female trees leaf earlier?

Gaia Gardener: said...

I've never known there to be a specific difference in leafing out time between male and female cottonwood trees, but it would certainly be worth observing. It would be great if you could "foretell" the sex of individual trees before they are actually old enough to produce flowers.

Differences in timing for leafing out can simply be related to normal genetic variability, though. We have 3 naturally occurring pignut hickory trees on our current property that show distinctly different schedules for leafing out. They vary by several weeks in both their timing of breaking dormancy in the spring and leaf drop in the fall. Genetic variability like this is one of the main reasons why native plant enthusiasts and certain other gardeners recommend using seed grown plants, rather than plants that come from cuttings or other "cloning" types of reproductive measures.

Certainly, as a gardener who is concerned about climate change, I am thankful for genetic variability, since certain changes may make it easier for particular individuals in a plant species to survive changing conditions.

Shady Hollow Resort said...

Are they different colors in the fall too?