Midewin National Tallgrass Prairie
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  • Slender Yellow Loosestrife

    SCIENTIFIC NAME: Lysimachia quadriflora

    COMMON NAMES: Slender Yellow Loosetrife, Prairie Loosetrife, Four-flower Yellow Loosestrife, Linear Loosestrife, Narrowleaf Loosestrife, Whorled Loosestrife

    BLOOM TIME: July, Aug


    • Erect 2 ½ in. tall ascending to hairless, green central stem; ¼ in. leaves.
    • Tiny yellow flowers are ¼ to 1 ½ in. long, with 5 central slim lobes & there are 3-4 on ends of upper stems.
    • Habitat: wet prairies & seepy river banks; found in high quality wetlands.
    • Uncommon in central and northern Illinois.   
    • Long ago thought that plant had soothing powers over animals so people tied a branch to oxen yoke thinking it made them easier to handle.
    • Known to repel gnats & keep snakes away.


    • Flowers are cross-pollinated by oligolectic Melittid bees. These bees collect floral oil & pollen of flowers to make pollen balls they feed to their larvae.
    • Loosestrife Bud Gall Midge larvae, sawfly, & Loosestrife Borer Moth larvae feed on the foliage, pith of stems, & other parts of loosestrife.
    • No information is available about this plant's relationships to vertebrate animals.