Virtual Tour


It might be ok to climb if you're an ant, but any large animals, including people, would be in a lot of pain from the very sharp thorns on this Washington hawthorn tree. Why do you think some plants have thorns? Well, if you were a large animal and were going to try to eat a branch from this tree, how would it feel in your mouth? Yes, ouch! Plants that have thorns are very well protected from being eaten alive.

Thorn growing on a Washington hawthorn tree
Thorn growing on a Washington hawthorn tree.

Bonus fact:
Another sharp plant defense is the "spine." Cactuses have spines. Spines are different from thorns. Thorns are special types of small branches (see how they're growing out of the trunk of the tree?). Spines are very thin and sharp leaves.

Look at the pad of this cactus. It is actually a plant stem. The spines—leaves that evolved to be sharp points—grow right out of this stem.

Prickly Pear Cactus                                     

Now look at this holly leaf. Are the sharp tips thorns or spines?

Holly leaf  

How to find the hawthorn at the Arboretum:
Enter the National Herb Garden and turn right. Stay on the brick path until you enter the area with the large oval grass center. Turn right and look for the hawthorn trees on your left, growing in front of the Dye and Colonial Gardens.

Scientific name for Washington hawthorn: Crataegus phaenopyrum

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Last Updated   July 10, 2009 9:20 AM