Posted tagged ‘epizoochory’

The Burry Man, The Burry Dog, and Burdock

October 18, 2010

The Burry Man sips whiskey through a straw. Photo by Homer Sykes, 1971

Starting in late August, burrs rank high on the Official List of Naturally Occurring Seasonal Aggravations. A recent light-hearted walk along Riverside Park’s upper path turned suddenly burry when Esau, in hot pursuit of temptation-in-a-squirrel-suit, dived into a low tangle of underbrush and emerged looking like the Burry Man of the British Isles.

The Burry Man and his attendants

For more about the Burry Man, including his origins and family relations (among them,  The Green Man, Poison Ivy, Robin Hood, army snipers and Sasquatch) click here.

But first, the Burry Dog … and his burrs.

A few remaining eyebrow burrs

In a matter of seconds, Esau had amassed at least 50 burrs from his ears to his tail. While some burrs operated alone, many clumped together into giant burry conglomerates.

Burr cartel takes hind leg by storm

I de-burred the pads of Esau’s little hairy feet, but the corporate burrs either resisted removal or broke apart into tiny spiked seedlets that clung to my fingertips and buried themselves beneath Esau’s fur.  We abandoned our walk and headed home, where Esau submitted reluctantly to scissors.

Elvis's Army buzz is in Esau's future.

The experience left me wondering: what’s the deal with burrs, anyway? Why do they cling with such persistence to pants legs, hair, fur and shoes?  Where do they come from and what do they want?

Burdock in bloom

Riverside Park’s burrs are seeds of the burdock plant, a non-native – some might say, invasive – species of thistle from across the pond.  Do not be fooled by the pretty purple flower. Burdock has an evil plan, and you and your dog are part of it.

What burdock wants is to populate new territory with its progeny.  But how?

Think about it.  You’re a burdock seed. You need to get away from your overcrowded home and make your own way in the world.  But you have no legs. You have no wings.  You have no car, and no money for a Greyhound ticket.  How are you going to get out of Dodge?

The answer is simple: Hitchhike.

Going my way?

“But how?” you protest. “I didn’t evolve a thumb.”

True. But you did evolve nasty little hooks that allow you to attach yourself to any furry, woolly or hairy animal that happens to brush by you.  You will use that poor sucker’s mobility to move yourself out into the world.

Traveling on an animal’s exterior is  called epizoochory and is a fairly unusual method of seed dispersal, used by only 5% of plants.  Far more common is endozoochory, in which seeds travel inside an animal by being eaten and excreted. This is, in my nonscientific opinion, a much more harmonious method that benefits both plant and animal.  I pity wild animals with massive burrs entangled in their fur and no fingers or scissors to free themselves.

Other common methods of seed dispersal include wind, water and – I kid you not – “ballistics,” in which the plant itself expels the seed.  That’s for a future post.  But before we look at exploding plants, be sure to click below for facts, lore and video on …

THE BURRY MAN.

The Burry Man, The Burry Dog and Burdock is part of the Carnival of Evolution #29. Visit the C of E for wonderful posts on evolution by real live scientists. (We’re not sure how Out Walking the Dog slipped into the carnival, but we like the company.)


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