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See list of 5 genera in this family
  • 1a. Leaves dimorphic—submersed ones that are opposite and finely dissected and floating ones that are alternate, borne in a crowded rosette, and have rhombic blades borne on inflated petioles [Fig. 717]; fruit indehiscent, caltrop-shaped, with 4 stout horns
  • 1b. Leaves monomorphic, neither dissected nor with inflated petioles [Figs. 714,715,716]; fruit a capsule
    • 2a. Corolla zygomorphic; hypanthium swollen or spurred near the base on one side; flowers with (6–) 11 or 12 (–14) stamens
    • 2b. Corolla actinomorphic; hypanthium neither asymmetrically swollen nor spurred; flowers with 4–10 stamens or commonly 12 in Lythrum salicaria
      • 3a. Hypanthium cylindric to narrow-cupuliform, 2 or more times taller than wide, with 6 or 12 conspicuous veins; perianth (5–) 6 (–7)-merous; leaf blades sessile or subsessile (narrowed to the base in L. virgatum)
      • 3b. Hypanthium hemispheric to broad-cupuliform, ± as tall as wide, without evident veins or with 4–8 evident veins; perianth (3–) 4 or 5 (–7)-merous; leaf blades borne on short petioles or narrowly tapering to an ill-defined petiole
        • 4a. Petals evident, 10–15 mm long, deciduous [Fig. 714]; flowers with 8 or 10 stamens; intersepalar appendages linear, much narrower and longer than the sepals; leaf blades 50–150 mm long; plants perennial, with ± woody bases surrounded by loose, spongy tissue
        • 4b. Petals minute, 0.5–1 mm long, caducous [Fig. 716]; flowers with (3–) 4 (–6) stamens; intersepalar appendages triangular, ± similar in size and shape to the sepals; leaf blades 10–30 (–50) mm long; plants annual

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 Show photos of:   Each photo represents one genus in this family.