Thursday, June 25, 2015

Sex in the Grass

I was poking though old posts recently, spotted a minor typo in this one, thought, "what the heck," and corrected it.  That's when I made an important discovery: Blogger moved the post to the current date (from late June 2014 when originally posted), so that it went to the top of the blog.  Now I've learned my lesson, but will add this preamble and bump it once more, now that grasses are again coming into glorious flower

Okay: really "sex among the grasses" would have been more accurate--but would it have gotten your attention?

The grasses in my neighborhood are all hot-to-trot right about now, and that gives me the chance to talk about a pet peeve: the way people use the term "flower."  

A great many people are unaware of most flowering plants because they only notice flowers that are large and showy.  But showiness is just that: a bid to attract attention.  --just not ours.  

Showy flowers are in the business of attracting pollinators, to overcome one of the key disadvantages of the rooted life: an inability to go out dating.  For any sexual reproduction, sperm from the male must get to the egg of the female.  For most animals this is not a problem: they can move.  For plants it is a biggie.

Most plants overcome this problem by enclosing their sperm in a pollen grain, and then having some way to get this pollen grain from the male part (stamen) a longish distance to the female part (pistil) of the flower on another plant.  Most flowering plants do this with the help of animals recruited for the purpose.  These animal "chaperones"* are informed  of a plant's randy status with colors or odors, and  bribed with nectar or the like to be the go-between.  In a typically mutually beneficial arrangement, the animal (whether bee, bat, bird, etc) gets a reward for delivering the pollen to the receptive stigma of a flower on another plant, and then Baby is on the way.  Of course, it's helpful if you and your Honey are in the mood at the same time: hence flowering seasons.    More people should blush at the sight of blatant sex all around them.

Of course, the contented beetles are a good clue, but
how else can you tell that the swamp dogwood above is insect-pollinated, 
but the pignut hickory below is not?

Not all plants use animals as go-betweens.  Some prefer to let their love waft on the wind.  Among these are conifers, of course; the sperm-bearing pollen that pines coat all surfaces with at this time of year is the detritus of a veritable orgy.  But some flowering plants are also wind-pollinated: familiar oaks and maples release pollen from small, inconspicuous flowers with tiny, dull-colored petals because they have no need to attract animals.  One downside of this habit--at least for many of us--is seasonal allergies.  

 A few wind-pollinated trees: Norway maple, scarlet oak, and paper birch.

 The grasses go these trees one better: they don't even have petals.  For grasses, in particular, wind pollination makes sense: grasses typically live in in dense stands in which likely sexual partners are close by, so a little breeze is all that's required to complete the tryst. 

A few grasses from my neighborhood.

*In an old and jocular sense, and rather the opposite of what their parents intended.

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