Purple Loosestrife – Cultivar Fertility

Purple loosestrife is a perennial herb, an emergent aquatic noxious weed, and a species that is prohibited for sale in the state of Washington. As a noxious weed, control is required in designated areas of the state, or in areas as deemed appropriate by county weed control boards. Control is defined as preventing all seed production. Lythrum salicaria, L. virgatum, and all cultivars are prohibited for sale by the Washington State Department of Agriculture. Why is it illegal to buy or sell any cultivars? In 1987 the Minnesota Department of Agriculture (MDA) declared purple loosestrife (Lythrum salicaria) a noxious weed, due to the alarming spread in its wetlands. All sales of this species were also prohibited. At this time, The MDA did not prohibit the sale of L. virgatum, or the cultivars – partly out of sympathy for the nursery industry. The cultivars of L. virgatum were considered sterile AND it was thought the cultivars could be morphologically identified from purple loosestrife. By 1988 both species were listed as noxious weeds (in Minnesota), and any and all cultivars were prohibited for sale. In 1989 research was underway to determine whether or not the cultivars of L. salicaria or L. virgatum were indeed sterile. Lythrum Reproductive Morphology