Thorns, Prickles, Spines and Bristles

 

Plants have several ways to grow armor to discourage animals from browsing on them.

 

A thorn is a sharp, pointed, modified branch or stem.  It can be at the end of a stem, or be its own short pointed woody branchlet.

Buffalo Berry – photo courtesy Steve Matson

 

A prickle is an outgrowth from the skin of the stem.  It’s a kind of stiff, sharp hair that grows from the epidermis. 

Himalayan Blackberry – photo courtesy Zoya Akulova-Barlow

 

A spine is a hard, sharp, pulled-together leaf or flower part.  They’re often found at leaf margins.  Sometimes the whole leaf becomes a spine, such as with Cactus.

Arizona Thistle – photo © Frank Rose, Desert Museum

 

A bristle is a dry, colorless, stiff hair.  In leaves, bristles are an extension of a leaf vein that goes beyond the margin. 


Black Oak – illustration © John Muir Laws

 

In dandelion pappus, bristles are appendages to the fruit, creating a parachute to fly away on.

 

In fact, the term bristles, as with hairs, is more about the look of an appendage rather than its structure.  Stems and flower parts have a wide variety of them.

 

Want more?  See Wikipedia.

 

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