Of Spines, Thorns, and Things that Poke in the Night

Of Spines, Thorns, and Things that Poke in the Night
By Ron Harton
Naturewriting.com

Spines on the other hand are modified leaves. They are formed of different material from the stems out of which they grow. The best example of this modification is the cactus. A cactus stem is soft and succulent because it stores water. The stem is green because it contains the chlorophyll that enables the plant to photosynthesize food. The spines which grow from the cactus stem are hard and solid. The spines grow from the base in the same way that leaves grow. However, unlike normal leaves, spines are saturated with calcium carbonate and pectin to make them stiff and hard. They contain no chlorophyll for food production, but they are extremely important to the plant in several other ways.

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