story to find out more.
Walnuts come in a variety of shapes and sizes.
Clockwise from top: Eastern Black (J. nigra), American butternut (J.
cinerea), Texas Black (J. microcarpa) and Persian/English (J.
regia). Click the image for more information about it.
World's Walnuts Flourish in California Research
By Marcia Wood
August 5, 2005
Crunchy, good-for-you walnuts sold in
supermarkets across America are typically the English or Persian kind, known to
scientists as Juglans regia. This popular nut likely originated from Persia.
It's thought to have taken on the "English walnut" moniker when,
centuries ago, British trading ships brought it to ports around the globe.
This familiar walnut belongs to a family of more than a dozen other species.
Many of them are flourishing in a unique research orchard in northern
California, managed by scientists with the Agricultural Research Service (ARS). With species from both the Old and
New World, it's the largest, most genetically diverse walnut collection
anywhere, according to ARS research horticulturist and curator
Stover at Davis, Calif.
Headquartered in Davis, the collection is part of what's officially known as
Clonal Germplasm Repository for Tree Fruit and Nut Crops and Grapes. ARS
manages a nationwide network of such genebanks. These valuable genetic
collections help prevent the rich genetic diversity, or gene pool, within crop
plants and their rare, wild and unusual relatives from being lost forever to
insects, diseases or urban sprawl.
Among the collection's most unusual walnuts are some J. regia trees from
Armenia. Oddly, their shells are somewhat larger than a golf ball, but the nut
meats inside are only of average size.
Researchers, breeders and plant nursery managers can use this remarkable
genebank, according to Stover. Here's an example: Several years ago, ARS
K. Aradhya, based at Davis, and his
University of California at
Davis co-investigators developed a set of what are known as walnut
Based on a tree's distinctive genetic material, or DNA, markers help
breeders and others quickly and accurately "fingerprint" individual
J. regia trees, for instance. That, in turn, helps avoid costly mixups about
"who's who" among walnut trees in nurseries, orchards or backyard
more about the research in the August 2005 issue of Agricultural
ARS is the U.S. Department of
Agriculture's chief in-house scientific research agency.