The Mysterious Physical Attraction of Slash Pine Seeds to … Anything

Pine cones are falling from the sky and smacking the roof with a thud, with all the earnestness of a piece of reentering space debris. The sound reverberates among the rafters, giving the impression of a large falling limb, sending us scurrying outside searching for damage to the roof.

It is October in the Florida Pan Handle, the time of year when pine cones eject their winged pine seeds.  Once emptied, the cones are rejected by their parental trees like useless appendages.

Those seeds had begun their race towards destiny high in the outstretched branches of 100-foot tall slash pines, being nestled by the overlapping leaves of their natal cones. But once ejected from their nest, they were on their own, distributed by gravity, winds, and those always tricky helicopter aerodynamics.

Walking outside this morning I could see those seeds helicoptering down to the ground, or the pool. Those landing fruitlessly, without hope on the concrete were distributed forlornly like bodies on a battle field. But those landing in a pool, being swept towards the uncaring maw of the pool skimmer, did something interesting.

It reminded me of illustrations of the attempted fertilization of human eggs by sperm; all lined up, jockeying to be the first to the prize. The heavier seed end of the wing seemed to be attached to the pool ladder as if by magic, although I suspected some subtle electrical charge interaction with the metal.

This was not occurring in still water; there was a considerable flow carrying unattached seeds swiftly past those clustered around the ladder.

Click to enlarge.

But then I saw the seeds clustering around other objects, the walls of the pool, and in an almost Oedipal fashion, a pine cone floating in the pool. One cluster of seeds were touching their ends together as if in some group incest.

Keep in mind, each seed fluttered down on its own, singly. Yet when they met in the water they had an unexplained physical attraction, literally.


The last two photos made me suspicious that the attraction was not based on electrical charge, but on surface tension — somehow. In the photo of the pine cone you can see dimples in the water around the wings and seed, an observation that positively screams surface tension.

Just how surface tension works to orient these seeds in the way they do is unclear to me. However, I see an evolutionary benefit.

Concrete pools are not of nature. In nature, seeds falling in water might be benefited if surface tension orients the seed end towards the edge of whatever stream or pond the seeds fall into. If the seed ends can touch the soil of the earthen banks, then they have a chance to germinate.  If the seed ends pointed away from the soil, they would eventually become water logged and sink, thus drowning the potential pine seedling.

In the following short video clip we see the strange maneuvering of three separate seeds, unattached except through some invisible force, moving to and fro in the eddy behind a pool ladder in a relatively swift current.

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One of the many joys of being human is discovering the beauty and mystery in nature. You don’t have to understand it to appreciate it.