Northern Prairie Wildlife Research Center
Purple Ammannia (Ammannia coccinea)
- Family: Loosestrife (Lythraceae)
- Flowering: July-September.
- Field Marks: Ammannia has more than one flower in the axils of leaves, while Rotala, a very similar genus in the family, has only one flower. Purple ammannia lacks flower stalks and has 4 pink-purple petals less than 1/4 inch long. The leaves are opposite with a pair of shallow lobes at the base.
- Habitat: Wet, open soil, often along the margins of ponds and lakes; wet meadows.
- Habit: Annual herb from a tuft of roots.
- Stems: Usually solitary, erect, smooth, sometimes branched, usually 4-angled, up to 1 1/2 feet tall, often turning reddish.
- Leaves: Opposite, simple, linear to narrowly lanceolate, pointed at the tip, usually with a pair of shallow lobes at the base, without teeth, up to 3 inches long, up to 1/2 inch wide.
- Flowers: 2-5 in the axils of the leaves, each about 1/4 inch long, usually without a stalk.
- Sepals: 4, very short, forming a small cup.
- Petals: 4, pink to pink-purple, up to 1/4 inch long, falling away early.
- Stamens: 4 or 8.
- Pistils: Ovary superior.
- Fruits: Rounded capsules 1/4-1/2 inch in diameter, with minute shiny, yellow seeds.
- Notes: The tiny seeds are eaten by waterfowl. This species is sometimes called Tooth-cup.
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