A Potpourri of Pistachios
America's official pistachio
collection is kept at a
northern California orchard
preserve known as the ARS
National Clonal Germplasm
Repository for Fruit and
Nut Crops. More than 750
pistachio trees are safe-
Those crunchy pistachios that make a perfect mid-afternoon snack are
most likely to have come from Kerman pistachio trees, this country's
most popular kind of commercial pistachio. Kerman trees, along with
other domesticated pistachios and their unusual, wild, and rare relatives,
thrive in America's official pistachio collection. This northern California
orchard preserve, known as the ARS
National Clonal Germplasm Repository for Fruit and Nut Crops, safeguards
more than 750 pistachio trees.
Headquartered at Davis, California, the collection is part of a nationwide
network of ARS-managed plant repositories established to protect the
natural genetic diversity, or gene pool, of crop plants and their uncultivated
cousins. Plant breeders, researchers, and others use these collections
to develop new varieties or discover more about the lineage of existing
The Davis collection includes 10 pistachio species and various hybrids
from near and far. Among them: two species native to North America,
Pistacia mexicana and P. texana; and exotic specimens
from Afghanistan, China, Greece, India, Iran, Israel, Italy, Kazakhstan,
Pakistan, Syria, Turkey, Turkmenistan, and Tunisia.
Cultivated pistachios like Kerman, many of which are different varieties of P. vera, bear their first crop at age 5 or 6, produce nuts only on female trees, and require pollen from nearby male pistachio trees to do so.
California: Top U.S. Producer
Some pistachio varieties in the collection, like Damghan, Iran Large,
and Rashtiall P. vera types from Iranbear nuts that
are as large as, if not larger than, Kerman. But these varieties aren't
as well suited as Kerman for growing in California, where most of America's
300-million-pound pistachio harvest is produced.
Nuts of wild pistachio species are considerably smaller than those
of their domesticated cousins, according to ARS geneticist Mallikarjuna
K. Aradhya, the Davis repository's crop manager for pistachios. An exception:
domesticated P. vera's closest wild relative, P. khinjuk,
which produces nuts that vary from small to almost as big as those of
Many kinds of pistachio trees that aren't cultivated for their nuts
are instead used as rootstocks to which the upper, nut-bearing portion
of the tree, or scion, is grafted. Or, these species are planted as
street trees, especially those like P. chinensis, which has spectacular
red and orange foliage in fall.
Besides being fun to eat, pistachio nuts are a boon to our health.
They provide fiber; vitamins B1, thiamin, and B6; magnesium; phosphorus;
and copper; plus smaller amounts of vitamins A, B9 (folate), and E;
and calcium, iron, potassium, selenium, and zinc. The nuts also contain
lutein, thought to help eye health, and beta-sitosterol, which may help
reduce cholesterol.By Marcia
Wood, Agricultural Research Service Information Staff.
This research is part of Plant, Microbial, and Insect Genetic Resources,
Genomics, and Genetic Improvement, an ARS National Program (#301) described
on the World Wide Web at www.nps.ars.usda.gov.
Mallikarjuna K. Aradhya
is with the USDA-ARS National
Clonal Germplasm Repository for Fruit and Nut Crops, One Shields
Ave., Davis, CA 95616; phone (530) 752-6504, fax (530) 752-5974.
"A Potpourri of Pistachios" was published in the November 2004 issue of Agricultural Research magazine.