Why Pumpkins Are Orange

 A pumpkin patch at Stahlbush Island Farms, Oregon (photo by Gary Wilson, USDA Natural Resources Conservation Service).

A pumpkin patch at Stahlbush Island Farms, Oregon (photo by Gary Wilson, USDA Natural Resources Conservation Service).

Pumpkins are a type of squash. They grow on a vine and come in many varieties and sizes, ranging from small ones that weigh less than a pound to enormous ones that weigh in at more than 1,000 pounds. When pumpkins first begin to grow, they are green. The green color comes from a pigment in the plant called chlorophyl.

According to the Children's Museum of Indianapolis, many (but not all) pumpkins turn orange in the fall in the same way and for the same reasons that leaves on some deciduous trees turn orange. As autumn approaches, the amount of daylight is lessened and temperatures fall. This causes the chlorophyl to degrade, allowing different types of pigment to show through. In the case of pumpkins, carotenoids (the source of alpha and beta carotene) result in orange hues.

Some pumpkins are selectively bred to yield other colors. Kate Smith, writing for Sensational Color, describes red, pink, green, tan, white, and even blue varieties in "The Many Colors of Pumpkins."

Eighty percent of the pumpkins in the United States are available in October. Although they are frequently used for fall-themed decorations, pumpkins also provide important nutrients and are a featured ingredient in soups, breads, and pies. According to the University of Illinois Extension, "The largest pumpkin pie ever made was over five feet in diameter and weighed over 350 pounds. It used 80 pounds of cooked pumpkin, 36 pounds of sugar, 12 dozen eggs and took six hours to bake." For more facts about pumpkins, see "Pumpkins and More," from the University of Illinois Extension.

This article originally appeared in the October 2015 issue of Observations: A Pier Press® Newsletter. You can access the archived issue here, and if you're not already a subscriber, click here to sign up. It's free.