How Wild Plants
Invade Our Backyards

Geranium fruitsAt the right you see something amazing, despite the fact that what's pictured is a sprig of a very common weed I just snipped from the path leading to my door. This is a cluster of fruits and flowers of the plant called Wild Geranium, Geranium carolinianum. Sometimes this plant is also called the Carolina Storkbill because the the fruit consists of that long, dark object you see arising from the center of three old flowers (one young flower with its pink petals is at the lower right), which reminds some people a stork's long bill.

In this species, the base of each "bill" expands into five baglike things (the five carpels of the earlier ovary). When the fruit is ripe, the baglike things break away from one another and the bag's "handle," which runs up the "bill," violently recoils, making the "bag" snap upward. During this process, the "bag's" seed is tossed away from the plant. In other words, each flower has five built-in "catapults" that physically toss the seeds into new territory. In the picture, two flowers show one of their "catapults" just after it's snapped upward. In the middle flower, inside the calyx, you can see two " unsnapped bags" waiting for their turn to be catapulted.

All seed-dispersal mechanisms are not this amazing, but, all-in-all, figuring out how plants spread their seeds into new territory is a fascinating subject. Here are the main ways most, but not all, plants do it:

WIND is the main transporter of most fruits and seeds of wild plants invading our backyards. Here are some adaptations enabling fruits and seeds to travel on the wind:

ANIMALS are the other main transporters of plant fruits and seeds into our backyards. Here are the main ways they accomplish that:

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