Also called Spiked Loosestrife and a number of less polite names, this is one of our most attractive ecological disasters. Purple Loosestrife is a simply glorious flower that can invade wetlands and displace everything else. This stand was growing by the Allegheny in O’Hara Township, where it was blooming in the middle of September.
Gray describes the genus and the species:
LYTHRUM L. LOOSESTRIFE. Calyx cylindrical, striate, 6-7-toothed, with as many little processes In tlx sinuses. Petals 6-7. Stamens as many as the petals or twice the number, inserted low down on the calyx. Capsule subcylindrical, 2-celled. — Slender herbs, with pink or magenta (rarely white) flowers in summer. (From lythros, blood; perhaps from the styptic properties.)
Stamens 12 (rarely 8 or 10), twice the number of the petals, 6 longer and 6 shorter; flowers large, crowded and whorled in an interrupted spike.
L. Salicaria L. (SPIKED L.) More or less downy and tall; leaves lanceolate, heart-shaped at base, sometimes whorled in threes; flowers magenta, trimorphous in the relative lengths of the stamens and style; calyx and bracts greenish, somewhat pubescent, the calyx-lobes much shorter than the subulate appendages. — Wet meadows, local, N. E. to Del. and D. C. (Introd. from Eu.) June-Sept. Var. tomentosum (Mill.) DC. Calyx and bracts white-tomentose. — Wet meadows and shores, e. Que. to Vt. and s. Ont. (Nat. from Eurasia.)