In 1910, Wilmatte Porter Cockerell, a high school biology teacher, noticed a red sunflower growing in the wild across the street from her home near 10th Street and Aurora Avenue in Boulder. Along with her husband, Theodore Dru Allison Cockerell, a professor at the University of Colorado Boulder, Cockerell transplanted the sunflower into her own garden. The flower was a "sport," a spontaneous mutation resulting in morphological differences in a plant. With their backgrounds in the sciences, the Cockerells knew that sunflowers are unable to be fertilized with their own pollen, and so experimented in cross-pollinating the sunflower with others until the desired red color was visible in the flower's offspring.
Eventually, the Cockerells were able to sell seeds carrying the red mutation to seed companies and were recognized at the 1915 Panama-Pacific International Exhibition for their work in cultivating the unique flowers. The many varieties of red sunflowers available all over the world today are believed to be descendants of the one carefully tended by the Cockerells in Boulder, Colorado.
The CU Boulder Libraries Archives, part of Rare and Distinctive Collections, holds a sizable collection of materials from Theodore Cockerell, along with notebooks and correspondence belonging to Wilmatte Cockerell. In addition to academic correspondence, writings, and research notes, the collection also includes over 60 film reels, glass slides, film equipment, and the actual preserved red sunflower grown in the Cockerells' garden.
The pages below for Henderson's New Red Sunflowers are taken from the 1915 Everything for the Garden seed catalog. The advertisement references "a professor of biology in the West" and describes the Cockerells' use of Mendelian genetics to produce subsequent plants that flowered red. Note the caution that "plants may produce all yellow flowers." Are your sunflowers growing with entirely red flowers?
A scanned version of the full Everything for the Garden seed catalog is available through the Biodiversity Heritage Library.
