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Beach Knotweed
Polygonum paronychia
  
About Beach Knotweed (Polygonum paronychia) Nurseries Show All Photos Polygonum paronychia is a species of flowering plant in the knotweed family known by the common names dune knotweed, black knotweed, and beach knotweed. It is native to the coastline of western North America from British Columbia to California, where it grows in sandy coastal habitat such as beaches, dunes, and scrub. Polygonum paronychia is a small prostrate or upright shrub producing multibranched brown stems up to a meter (40 inches) long. The stems may root at nodes that come in contact with moist substrate. The leaves are alternately arranged on the stems but are mostly located bunched around the tips of the stem branches. The leaves are linear to lance-shaped with rolled edges and bristly midribs on the undersides. Each leaf has a large stipule which forms a wide, membranous ochrea. The ochrea is up to 2 centimeters (0. 8 inches) long and is persistent, fraying into fibrous, silvery shreds that remain on the plant through the seasons. Flowers occur in the leaf axils. Each is up to a centimeter (0. 4 inches) wide with five narrow white or pinkish corolla lobes. Polygonum paronychia is a small prostrate or upright shrub producing multibranched brown stems up to a meter (40 inches) long. The stems may root at nodes that come in contact with moist substrate. The leaves are alternately arranged on the stems but are mostly located bunched around the tips of the stem branches. The leaves are linear to lance-shaped with rolled edges and bristly midribs on the undersides. Each leaf has a large stipule which forms a wide, membranous ochrea. The ochrea is up to 2 centimeters (0. 8 inches) long and is persistent, fraying into fibrous, silvery shreds that remain on the plant through the seasons. Flowers occur in the leaf axils. Each is up to a centimeter (0. 4 inches) wide with five narrow white or pinkish corolla lobes.
Plant Description
Plant Type
Perennial herb

Max. Height
0.33 - 3.3 ft (0.1 - 1 m)

Flower Color
White, Red

Flowering Season
Spring, Summer, Fall
Spring
Summer
Fall
Winter


Native Status
Native

Natural Setting
Site Type
Dunes

Sun
Sun, Part Shade, Full Shade

Elevation ?
2' - 4336'

Annual Precip. ?
12.4" - 81.0"

Summer Precip. ?
0.17" - 2.79"

Coldest Month ?
42.1° F - 53.6° F

Hottest Month ?
56.5° F - 74.9° F

Humidity ?
0.01 vpd - 23.31 vpd

Drainage
Fast

Sunset Zones ?
4, 5, 14, 15, 16*, 17*, 19, 20, 21, 22*, 23*, 24*

Landscaping Information
Water Requirement ?
Extremely Low, Very Low
Extremely Low
Very Low
Low
Moderate - High


Propagation ?
For propagating by seed: No treatment.

Common uses
Groundcovers, Deer Resistant

Nursery Availability
Sometimes Available

Other Names
Common Names
Black Knotweed, Dune Knotweed



Sources include: Wikipedia. All text shown in the "About" section of these pages is available under the Creative Commons Attribution-ShareAlike License. Plant observation data provided by the participants of the California Consortia of Herbaria, Sunset information provided by Jepson Flora Project. Propogation from seed information provided by the Santa Barbara Botanical Garden from "Seed Propagation of Native California Plants" by Dara E. Emery. Sources of plant photos include CalPhotos, Wikimedia Commons, and independent plant photographers who have agreed to share their images with Calscape. Other general sources of information include Calflora, CNPS Manual of Vegetation Online, Jepson Flora Project, Las Pilitas, Theodore Payne, Tree of Life, The Xerces Society, and information provided by CNPS volunteer editors, with special thanks to Don Rideout. Climate data used in creation of plant range maps is from PRISM Climate Group, Oregon State University, using 30 year (1981-2010) annual "normals" at an 800 meter spatial resolution.

Links:   Jepson eFlora Taxon Page  CalPhotos  Wikipedia  Calflora


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