Knotweeds
Botanical name: Polygonum
Knotweeds
Botanical name: Polygonum
Description
The knotweeds (Polygonum) are a sizable and diverse group of mostly temperate flowering plants. Several species within this genus have historically been eaten by humans, although few have been widely cultivated as food sources. One exception to this is Madimak (P. cognatum), which is quite popular as a green in Turkish cuisine, and is today heavily cultivated in the central part of that country. Being hardy, colonizing species that spread quickly, several knotweeds are also considered pesky invasives beyond their native ranges.
Species of Knotweeds
Prostrate knotweed
Prostrate knotweed (Polygonum aviculare) is a low-growing species that can root practically anywhere. It produces many small white flowers each summer and produces plenty of seeds that can survive for years. Its seeds can lay dormant in soils, and once they see sunlight, they will start to germinate. Because it grows so dwarf, mowing is not effective in removing it.
Sawatch knotweed
Sawatch knotweed (Polygonum sawatchense) is an annual herb in the buckwheat family that is found throughout western North America. Like other flowering plants in the Polygonum family, this knotweed is known to attract the Purplish Copper Butterfly.
Oval leaf knotweed
Oval leaf knotweed (Polygonum arenastrum) is an invasive plant native to Europe that can now be found throughout North America as well. It sends out a long tap root that helps make it very drought-tolerant. Oval leaf knotweed prefers dense, compacted soils. Though a bane of large-scale farmers, it can usually be pulled by hand in smaller gardens.
Sea knotgrass
Sea knotgrass is a perennial plant that can be found growing on sand and shingle beaches. The Latin name, Polygonum maritimum, translates to "many joints" (polygonum) and "seashore" (maritimum). These refer to sea knotgrass's thick, woody stems, which the plant is renowned for, as well as the coastal areas it inhabits.
Ray's knotgrass
The ray's knotgrass (Polygonum oxyspermum) are a sizable and diverse group of mostly temperate flowering plants. Several species within this genus have historically been eaten by humans, although few have been widely cultivated as food sources. One exception to this is Madimak (P. cognatum), which is quite popular as a green in Turkish cuisine, and is today heavily cultivated in the central part of that country. Being hardy, colonizing species that spread quickly, several ray's knotgrass are also considered pesky invasives beyond their native ranges.
Shasta knotweed
The shasta knotweed (Polygonum shastense) are a sizable and diverse group of mostly temperate flowering plants. Several species within this genus have historically been eaten by humans, although few have been widely cultivated as food sources. One exception to this is Madimak (P. cognatum), which is quite popular as a green in Turkish cuisine, and is today heavily cultivated in the central part of that country. Being hardy, colonizing species that spread quickly, several shasta knotweed are also considered pesky invasives beyond their native ranges.
Beach knotweed
Polygonum paronychia is a small prostrate or upright shrub producing multibranched brown stems up to a meter long. The leaves are linear to lance-shaped with rolled edges and bristly midribs on the undersides. Flowers occur in the leaf axils, with five narrow white or pinkish corolla lobes.
Milkwort knotweed
The milkwort knotweed (Polygonum polygaloides) are a sizable and diverse group of mostly temperate flowering plants. Several species within this genus have historically been eaten by humans, although few have been widely cultivated as food sources. One exception to this is Madimak (P. cognatum), which is quite popular as a green in Turkish cuisine, and is today heavily cultivated in the central part of that country. Being hardy, colonizing species that spread quickly, several milkwort knotweed are also considered pesky invasives beyond their native ranges.
Seaside knotweed
The seaside knotweed (Polygonum glaucum) are a sizable and diverse group of mostly temperate flowering plants. Several species within this genus have historically been eaten by humans, although few have been widely cultivated as food sources. One exception to this is Madimak (P. cognatum), which is quite popular as a green in Turkish cuisine, and is today heavily cultivated in the central part of that country. Being hardy, colonizing species that spread quickly, several seaside knotweed are also considered pesky invasives beyond their native ranges.
Care Guide for Knotweeds
Scientific Classification
Phylum
Vascular plants Class
Dicotyledons Order
Pinks, cacti, and allies Family
Buckwheat Genus
Knotweeds 
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