Thursday, June 7, 2012
That's Not Snow
It is not unknown for snow to fall here in June. However, this drift of white that the wind has swept up on my deck is not snow.
It is cottonwood "cotton." This is yesterday's accumulation, and we have not yet reached the real height of the cotton season.
Usually I complain about the pesky cottonwood seeds floating in the breeze. In a heavy cotton season going outside is a trial, because it is filling the air and collecting on everything; but the worst part is taking a breath and breathing in cotton. But I have been thinking about other aspects of the annual cottonwood cotton season. (OK, I'll still probably gripe just a little when I want to be outdoors and the air is full of cotton!)
Cottonwoods grow to be huge trees. One would expect their seeds to be big, maybe like an avocado seed. But the mighty cottonwood grows from a very tiny seed, and this works wonderfully well for the cottonwood. Cottonwoods make thousands (maybe millions) of seeds each year. Each tiny seed is wrapped in very fine, fragile white filaments--thus the cotton appearance. This bit of fluff on each seed is exceedingly efficient as a seed dispersal system. A seed can float a long time and over a considerable distance when there is a little breeze. This is important.
Our part of the world is semi-arid prairie. In town there are lots of trees that people have planted, watered, and cared for so that they can survive and thrive. But this is not naturally tree country. Out where nature is the planter and caretaker, there are only certain places where a tree such as the cottonwood can grow. You can see cottonwoods growing around lakes or reservoirs, along creeks, or in ravines (draws) where snow collects in winter and where rain runs off into. These are the only places with enough water to nourish and sustain a tree.
So those tiny seeds surrounded by fluff and stickiness, riding the breeze by the millions, are necessary to keep the species going. The vast majority of them will never make trees. Even though they are amazingly fast germinating, without enough water the seedlings will fail. Only the few that find the right combination of soil, water, and space will get to grow.