Answer: Lythrum, or Purple Loosestrife, has escaped cultivation and become an invasive weed in many parts of the country. While it's pretty in the garden, Lythrum scatters seeds quite readily. Unless controlled by cutting back the flower spikes before seed formation, Lythrum has the potential to spread, displacing natural vegetation. Many states and counties forbid planting Lythrum, so make sure it's okay for your friend to plant it before you divide your plant or give her seeds. Since the seeds germinate so readily, it might be easiest just to collect seeds for her. Otherwise, divide the clump in the fall or early in the spring and replant the divisions.
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