Data provided by the participants of the Consortium of California Herbaria

View additional distribution information on the Jepson eflora

Swamp Knotweed (Polygonum amphibium) is a common native perennial herb in the Polygonaceae (Buckwheat) family that grows throughout California in almost every county. It is a wetland plant that is moderately fast growing and moderately long-lived. It grows in a rounded form to a height of 0.1 foot, with active growth during the summer. Flowers are yellow and bloom in the late spring. Leaves are medium green and deciduous. It tends to grow in shallow lakes and streams, at elevations from 0-10000 feet.

Plant type

Perennial herb

Size

8 - 48 in Tall

Dormancy

Winter Deciduous

Calscape icon
Color

Yellow

Special uses

Water features or wet habitats

Sun

Partial Shade

Sunset Zones

1*, 2*, 3*, 4*, 5*, 6*, 7*, 8*, 9*, 14*, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24

Site type

Shallow lakes, streams, shores

Plant communities

Chaparral, Foothill Woodland, Lodgepole Forest, Red Fir Forest, Subalpine Forest, Valley Grassland, Yellow Pine Forest, Wetland-Riparian

Caterpillars
Butterflies

Butterflies and moths supported

0 confirmed and 34 likely

Confirmed Likely

Garden Webworm Moth

Achyra rantalis

Civil Rustic

Caradrina montana

Guenée's Carpet Moth

Ceratodalia gueneata

Spotted Fireworm Moth

Choristoneura parallela