that purple weed

I’ve got too much time on my hands these days, as I don’t really feel like rummaging the thrift store. And the other day armed with a camera and magnifier I went to examine the purple loosestrife plants at the nearby walking trail.

I had read in Don & Lillian Stokes’s The Wildflower Book, that this beautiful but pernicious weed has three different arrangements of male and female parts, and I wanted to see them.

The plant’s sexual organs come in three different lengths: short, mid-length, long. These are arranged male-male-female, male-female-male, or female-male-male. All blossoms on any one loosestrife plant are of the same kind.

Now here’s the clever thing: A plant can only be fertilized when pollen from a male part lands on a female part of the same length. This means a plant can never fertilize itself, because only a different plant will have a male part of the same length as the female part.

This guarantees cross-pollination between plants, which confers distinct evolutionary advantages. Cross-pollinated plants are often better adapted to survival and reproduction than either parent, and they avoid the genetic deterioration that sometimes results from inbreeding.

As I scrambled about in the ditch, examining blossoms, I marveled at the scientific work that must have been necessary to discover and confirm the purple loosestrife’s curious reproductive strategy. There remains an even bigger untold story, of the exquisite molecular chemistry that regulates fertilization, and how that molecular chemistry is controlled by genes. The lock-and-key fit between loosestrife sperm and egg must be a thing of almost unbelievable subtlety and refinement.

And the big, big question is how such cleverness in nature comes about. That such refinement of design could have resulted from random mutations and adaptation to environment by natural selection seems, well, incredible.

Told you I’ve got too much time on my hands.

May all your weeds be wildflowers.

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