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Lysimachia ephemerum, which earned an RHS AGM for its garden performance, is a lovely cut flower that attracts a lot of butterflies. This elegant perennial thrives in moist borders and bog gardens, or at the edges of ponds and streams. Ghostly flower spikes with twinkling white blooms rise above silvery-green foliage clumps. Despite its benefits, this species of loosestrife is rarely seen in UK gardens. Height: 100cm (39). Spread: 30cm (12).