Northern Prairie Wildlife Research Center
Tooth Cup (Rotala ramosior)
- Family: Loosestrife (Lythraceae)
- Flowering: July-September.
- Field Marks: Tooth Cup has only one flower per leaf axil. Each flower has 4 tiny pink petals, but they frequently fall away after only a very short time. The narrow leaves are opposite and toothless.
- Habitat: Wet soil, often along margins of ponds and lakes, wet meadows.
- Habit: Annual herbs from a tuft of roots.
- Stems: 1-several, erect or rarely prostrate, often branched, smooth, up to 1 foot tall.
- Leaves: Opposite, simple, oblanceolate to linear, rounded at the tip, tapering to the base, without teeth, smooth, up to 2 inches long, less than 1/2 inch wide, sessile or with a very short stalk.
- Flowers: Solitary in the axils of the leaves, pink, up to 1/8 inch long, without a stalk.
- Sepals: 4, green, united below.
- Petals: 4, pink, free from each other, falling away early, sometimes completely lacking.
- Stamens: 1-6.
- Pistils: Ovary superior.
- Fruits: Rounded capsules up to 1/4 inch in diameter, with minute yellow or red seeds.
- Notes: The seeds are eaten by waterfowl. Another common name for this species is Pink Rotala.
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