Plant life is very lush in our area. If the landscape is not paved or has a building on it, it has plants growing on it if it sits long enough. Which begs the question: How do plants spread if they are literally rooted to the ground? The answer is in seed design, and several ingenious mechanisms are used to allow plant embryos (seeds) to move away from the shadows of the mother plant.

Seed dispersal is divided into several broad categories, including wind, animal transport, propelled, and dropped. The wind method is known to all who have picked up a mature dandelion seed head and blew on it to watch the little parachutes (each with a seed passenger) float off on the wind. There are lots of plants that use this method: milkweeds and thistle also use the parachute technique, and several use a single wing that spins around like a helicopter, used by maples, yellow poplar and ash.

Animal transported seeds fall into two groups: the clinging type are the sticky ones that attach themselves to fur or clothing. I have cursed seeds like beggar lice, stick-tights, seed ticks, cocklebur, and others that cover your pant legs when walking in weedy places.

The other animal mechanism is bribery. The plant produces a tasty fruit to entice an animal to eat it. The seed enclosed in the fruit passes through the gut of the animal unharmed and is pooped out far away from the mother plant with fertilizer to boot.

Propelled is where the seed has a mechanism to physically throws the seed away from the mother plant, kind of like a catapult. Touch-me-nots are a good example, having seed pods that are spring loaded, and when mature will release suddenly and throw the seeds all over the place. Witch hazel, wisteria, and winter cress all use this method.

I’ve seen gravity listed as a seed transport mechanism, and heavy round seeds like acorns, hickory nuts, and walnuts could drop off the tree and roll down the hill. But with most of our nut seeds, an animal transporter is more likely to come into play. The squirrel, while eating many nuts, also stockpiles them for winter use, hiding them in the ground in various places, a technique called caching. They don’t remember them all and some get to sprout and grow a new tree.

Observe seeds out in the wild and see if you can figure out the transportation method it uses. They are further proof that nature does all things with a purpose.

By: Steve Roark
Volunteer, Cumberland Gap National Historical Park