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If you’re as much of a plant nerd as we are, prepare to get absorbed. John E. Weaver, an American botanist, prairie ecologist and Professor at the University of Nebraska, completed a massive project in the year of 1927. With the help of his team of assistants, Weaver meticulously illustrated the root development of 34 popular vegetable crops (see the illustration of mature onion roots, right). In the massive undertaking that was partly botanical and partly archeological, Weaver and his team dug trenches approximately 5 feet deep to study the plant’s root systems from the side. The five-foot-deep trench created a big enough expanse onto which the scientists could slowly chisel with hand picks and ice picks to uncover and carefully examine the vegetable’s complicated root systems.
This painstaking work required much patience and expertise. The plants were studied and illustrated at multiple stages of growth in order to best represent general, long-term root habits. Every plant studied was grown in sets of at least three. This was done so that an excavation performed at two weeks of growth would not affect the results of an excavation performed after six weeks or two months. Every set of fragile roots was left undisturbed until it was time to dig.
Drawings of the root systems were made in the field on a large drawing sheet with pencil, and then later retraced with ink. Although the drawings were made on a large scale, the rootlets were often so abundant that it was still impossible to show every detail. In every case, the drawings were made to illustrate the average condition of the roots, rather than the extreme. Accompanying the illustrations are fastidious field notes regarding plant spacing, soil health, crop growth and more.
Weaver’s findings were published in Root Development of Vegetable Crops (1927), the sister publication to Root Development of Field Crops (1926). In 1929 Weaver partnered with ecological pioneer Henry Chandler Cowles to publish the first American ecology textbook.
The following illustrations are all documented on 1-by-1-foot grid lines.
Asparagus roots, 6 years
Bean roots, 1 month
Bean roots, 2 month
Bean roots, surface view, 6 inches
Beet roots, 6 weeks
Beet roots, 10 weeks
Beet roots, 3.5 months
Cabbage roots, 55 days after transplanting
Cabbage roots, 75 days after transplanting
Carrot roots, 47 days
Carrot roots, 77 days
Carrot roots, mature
Cauliflower roots, 3 weeks after transplanting
Cauliflower roots, 8 weeks after transplanting
Cucumber roots, 4 weeks
Cucumber roots, 6 weeks
Cucumber roots, surface view
Eggplant roots, 7 weeks
Lettuce roots, 3 week soil comparison. The roots on the right were grown in compact soil, the roots on the left were grown in loose soil. Avoid planting seedlings in compact soil by following the tips in this article, Care and Cultivation of Permanent Garden Beds.
Lettuce roots, 2 months
Onion seedlings of the same age. The one on the right was grown in compact soil, the one on the left in loose soil. Avoid planting seedlings in compact soil by following the tips in this article, Care and Cultivation of Permanent Garden Beds.
Onion roots, 8 weeks.
Onion roots, 3.5 months
Onion roots, mature
Pea roots, 6 weeks
Pea roots, mature
Pepper roots, 24 days after transplanting
Pepper roots, 6 weeks
Pepper roots, nearly mature
Radish roots, 5 weeks
Radish roots, 2 months
Spinach roots, 6 weeks
Spinach roots, 10 weeks
Sweet corn roots, 16 days
Sweet corn roots, 8 weeks
Mature sweet corn roots, view from above
Sweet potato roots, 23 days after transplanting a root cutting.
Sweet potato roots, 53 days
John E. Weaver and his team of assistants dug trenches approximately 5 feet deep to study the root systems of popular vegetable varieties.
Follow this link to see the online version of Root Development of Vegetable Crops.
Illustrations by John E. Weaver