Seeds can successfully disperse in many ways. Forgotten seeds hidden by birds and squirrels can germinate, but a seed covered by fruit is a more reliable strategy for plants. Elephants are particularly suited for spreading a large variety of seeds over great distances.
Over eighty families of plants depend on ants for seed dispersal. Although they do not travel very far, the ants move the seeds underground where they are safe from fire and rodents. Barbed plants use mechanical means that enable the seed to travel further away from the parent plant. Fresh water or seawater can also move seeds great distances. Besides heavy rains and proximity to rivers, seeds can be carried by watercraft, beavers, fish, and turtles. Coconuts are often ferried by ocean currents, but few seeds can tolerate saltwater. (In one of the enjoyable sidebars in her book Seeds, Carolyn Fry recounts how bath toys dumped by a ship travelling between Hong Kong and Tacoma during a storm vividly illustrate the power of ocean currents. The toys washed ashore in Japan, North America, Hawaii, Australia, Indonesia, and South America, while some were found frozen in Arctic ice.) Some seeds depend on self-propulsion or gravity. It is a method better suited to small plants. Wind-blown seeds are often able to colonize open areas with inadequate soils and harsh conditions such as deserts, sand dunes, and the boundaries of riverbanks and forests. The first species of plants to colonize the altered terrain of Mount St. Helens after its eruption were most likely from seeds carried by the wind. Winged seeds and gyrating seeds provide two methods of flight. Tumbleweeds are another example of wind dispersal. Seeds by Carolyn Fry was published by the University of Chicago Press in 2016.
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AuthorI am a Northwest artist making collages from mulberry papers stamped by hand from original images that I have carved. Archives
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