By definition, a prune is a dried plum.  All prunes are plums, but not all plums are prunes.  Prunes can be dried without fermenting while still containing the pits.   This is not true of other varieties of plums.  It should be noted that when we plant an orchard, we plant a prune orchard.

    The first prune trees in America are reported to be planted in the Santa Clara Valley of California in 1856.  The original prune graft came from D'Agan root stock from France.   Today the D'Agen prune has come to be known as the California French Prune, and constitutes about 99% of the states production.  Most of the production lies in the Sacramento Valley.  Here, the rich valley soil, the climate, and the abundant water supply, are ideal growing conditions and result in high quality prunes.