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.
Now look at this holly leaf. Are
the sharp tips thorns or spines?
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
Go directly to a specific tour stop by clicking a specific spot on the Map above
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Last Updated July 10, 2009 9:20 AM
URL = http://www.usna.usda.gov/Gardens/collections/VirtualTours/KidsVirtualTour_08b.html