Low Smartweed

Low Smartweed (Persicaria longiseta) is in the knotweed family family (Polygonaceae). Across the U.S., iNaturalist users have logged 2,566 research-grade flowering observations of it in our sample, peaking in September.

Nationally it blooms mainly from June to October, but timing varies a lot by state and elevation — see the table below.

When to photograph Low Smartweed: observations by month (U.S.)

About Low Smartweed

Persicaria longiseta is a species of flowering plant in the knotweed family known by the common names Oriental lady's thumb, bristly lady's thumb, Asiatic smartweed, long-bristled smartweed, Asiatic waterpepper, bristled knotweed, bunchy knotweed, and tufted knotweed. It is native to Asia (China, India, Russia, Japan, Malaysia, etc.), and it is present in North America and Europe as an introduced species and often a weed.From Wikipedia via iNaturalist — article, CC BY-SA.

Low Smartweed by state

Main season = months with at least 30% of the state's peak-month count.

Related wildflowers (knotweed family)

California BuckwheatEriogonum fasciculatum

Desert TrumpetEriogonum inflatum

Sulfur BuckwheatEriogonum umbellatum

American jumpseedPersicaria virginiana

Naked BuckwheatEriogonum nudum

Japanese knotweedReynoutria japonica

American bistortBistorta bistortoides

Arrow-Leaved TearthumbPersicaria sagittata

Photography tips

• Photograph flowers on calm, overcast mornings to avoid wind blur and harsh shadows.
• Get low: a shallow depth of field (f/2.8–f/5.6) isolates a bloom against soft color.
• Stay on trails — trampling meadows kills plants and ruins next year's display.
• Try a kaleidoscope abstract of a single bloom with our online kaleidoscope tool.

FAQ