low smartweed (Persicaria longiseta) — identification, habitat & look-alikes

Low smartweed is an plant found on moist, disturbed ground, especially in the eastern United States. Its crowded pink flower spikes and long hairs fringing the papery sheaths around its stem joints help identify it. It is often called Oriental lady's-thumb.

Appearance

Appearance: This annual can trail at the base or stand upright, reaching about 1–3.2 ft (0.3–1 m). Its alternate leaves are narrow to oval, and the papery sheath at each node has a fringe of long hairs.
Flowers: Tiny dark-pink flowers crowd into slender spikes about 0.4–3 in (1–8 cm) long.
Flowering time: In the United States, it flowers from May through October, with timing varying by region.
Fruit: Each small, dark is usually three-sided and holds one seed.

Look-alikes

spotted lady's-thumbPersicaria maculosa

Spotted lady's-thumb (Persicaria maculosa) often has a dark leaf blotch and shorter hairs along the stem sheath. Low smartweed usually lacks the blotch and has longer sheath hairs.

Why they get mixed upBoth have narrow leaves and pink flower spikes.

Where it lives

Typical habitats: wet roadsides
fields and lawns
stream edges
Range: Nonnative in North America, it is concentrated in the eastern United States but has also been reported farther west, including parts of the Great Plains and Southwest.
Preferred conditions: It favors moist ground, can form large stands, and often appears where soil or vegetation has been disturbed.
Flowering: Flowers May–Oct
Flowers May–Oct

Life cycle

Reproduction: It reproduces by seed rather than spreading by underground or creeping stems. Seeds can remain in the soil and sprout after the ground is disturbed.

Name and classification

About the name: This plant was formerly called Polygonum caespitosum var. longisetum.

Conservation

IUCN Red List: NENot EvaluatedNot yet assessed

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