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Bigtooth Aspen Male Catkins

5-2-17 mystery photo 011

Aspens, cottonwoods, poplars – all are names for certain species of trees in the genus Populus. These trees, as well as birch, hickory, oak and willow trees, produce their flowers on spikes called catkins. Telling the catkins of these trees from one another is challenging, to say the least, yet some of NC’s readers correctly identified the catkins in the photograph as those of Bigtooth Aspen, Populus grandidentata. This tree blooms for one to two weeks in the spring and its mature male catkins open and extend to two to four inches in length. The wind, as opposed to insects, disperses the light, fluffy yellow pollen as the catkins dangle in the breeze. Some of the pollen remains intact even after the tree has shed its spent catkins onto the ground.

Because Bigtooth Aspen, and most species of Populus, are dioecious (male and female flowers develop on separate trees), there are only male flowers in this photo and beneath this tree. After fertilization, female flowers remain on the tree and form capsules which contain several small seeds embedded in tufts of fine, white hair. They will fill the air in several weeks looking like bits of floating cotton.

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6 responses

  1. It may have helped that the catkins are lying on a bed of last year’s bigtooth leaves.

    May 3, 2017 at 11:31 am

    • Yes, Will, I wondered if anyone would pick up on that. Not surprised that you did!!!

      May 3, 2017 at 6:41 pm

  2. Rita Pichette

    I have been a “nature person” all my life (70 years), yet I learn something from you almost everyday. You are amazing! Thanks for sharing what you know.

    May 3, 2017 at 11:53 am

    • Thank you, Rita. Those are very kind and generous words.

      May 3, 2017 at 6:41 pm

  3. Aha! Hence: “cottonwoods.” So that’s what those fluffy bits floating on the breezes are. Do those fluffs come, in some variation, from all the trees you mentioned above?

    May 3, 2017 at 12:06 pm

    • Most of the fluff is from Eastern Cottonwoods and Quaking/Trembling Aspen, but poplars of all sorts disperse their seeds in a similar manner.

      May 3, 2017 at 6:40 pm

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