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Weed Identification

American water-willow

Family

Acanthaceae

Scientific Name

Justicia americana

Other Common Names:

water-willow

Synonyms (former Scientific Names):

Dianthera americana var. subcoriacea
Justicia umbratilis
Dianthera americana
Justicia americana (L.) Vahl var. subcoriacea
Justicia mortuifluminis

Leaves

Arranged oppositely along the stem and are elliptic to linear in outline, approximately 6 inches long. Leaves have a distinctive white midvein that runs the length of the entire leaf.

Identifying Characteristics

The linear leaves with a white midrib, the prominent white lines along the stems, and the colonizing growth habit along shorelines are all characteristics that help to distinguish water willow from most other shoreline plants.

Flower Seed Head

Arranged oppositely on crowded spikes at the ends of long flower stalks (peduncles) that originate from the position between the leaf and the stem (leaf axils). Petals are white with purple tinges. Flowers have a distinctive lower lip that is approximately 3/4 inch long.

Seed Fruit

Stems: May reach 2 1/2 feet in height and are stout with prominent white lines. Fruit: A capsule that is approximately 1/2 inch long

Where Found

A perennial from rhizomes that is capable of forming large colonies. Water willow is primarily found along the shorelines or in shallow water of lakes, ponds, or streams.

Life Cycle

perennial

Plant Type

Herb