Polygonum arenastrum | |
---|---|
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Order: | Caryophyllales |
Family: | Polygonaceae |
Genus: | Polygonum |
Species: | P. arenastrum |
Binomial name | |
Polygonum arenastrum Boreau 1857 | |
Synonyms [1] | |
Synonymy
|
Polygonum arenastrum, commonly known as equal-leaved knotgrass, [2] is a summer annual flowering plant in the knotweed family Polygonaceae. Other common names include common knotweed, prostrate knotweed, mat grass, oval-leaf knotweed, [3] stone grass, wiregrass, and door weed, as well as many others. It is native to Europe [4] and can be found on other continents as an introduced species and a common noxious weed. Knotweed was first seen in North America in 1809 and is now seen across much of the United States and Canada.
Knotweed develops a deep tap root (it can be as deep as 18 in (46 cm)), does well in compacted soil, and survives drought conditions. The numerous wiry stems grow out from the center of the plant giving it a mat-like appearance. The stems are very long and branching and grow in a zigzag form. The leaves are alternate, oblong, hairless, can be 1⁄2 to 2+1⁄2 inches (12 to 37 mm) long, and are bluish-green in color. The leaf stalk is short and closely surrounded by papery stipules on each node. The stem nodes are slightly swollen and look somewhat like "knots", thus its common name, knotweed. Flowers, with colors ranging from white to green, are inconspicuous, have no petals, and grow all along the stems. The sepals, however, are pinkish with white edges. Seeds are egg-shaped, dark reddish brown in color, and have a smooth shiny surface.
In the US, knotweed can be mistaken for the native plant spotted spurge. An easy way to tell the difference is to break off a stem. Spurges contain milky sap; knotweed does not.
Since common knotweed does well in compacted soils, it is commonly found in brown-field sites, roadsides and pavements, driveways and in turf grass (where there is a lot of footpath wear) and in gardens.
Common knotweed germinates at or near the soil surface in early spring, as soon there is enough moisture, and grows in an upright position before it spreads out like a mat. If mowed, it will still spread and can form a mat as wide as 3 to 4 ft (0.9 to 1.2 m) in diameter. The seeds, which grow low to the ground, survive mowing and are not disturbed when stepped on by people and animals.
Knotweed is a weed of waste areas but has been showing up in grain fields, where is becomes problematic because of its prolific seed production and long viability. It is also a host for powdery mildew like Erysiphe betae and viruses such as beet ringspot and beet curly top virus.
Some sources treat Polygonum arenastrum as a subspecies or variety of Polygonum aviculare , [5] [6] [7] [8] while others differentiate. [9] [10] [11] [12]
In the home garden, common knotweed is easy to get rid of by hand pulling. Covering garden beds with landscaping fabric and then mulch is a good way to keep knotweed from taking over. If the seeds do germinate in the mulch cover, they are easy to remove. Herbicides are also an option. Pre-emergent herbicides, those that prevent the seed from germinating, are effective, but the area must first be free of weeds for this type of herbicide to work. Post emergent herbicides, those that kill the growing plant by spraying the green leaves of the plant, may be effective if applied when the plant is very young. [13]
To prevent this weed, the soil should be aerated and well-drained. Young weeds should be pulled before they set seed. [14]
Reynoutria japonica, synonyms Fallopia japonica and Polygonum cuspidatum, is a species of herbaceous perennial plant in the knotweed and buckwheat family Polygonaceae. Common names include Japanese knotweed and Asian knotweed. It is native to East Asia in Japan, China and Korea. In North America and Europe, the species has successfully established itself in numerous habitats, and is classified as a pest and invasive species in several countries.
Weed control is the botanical component of pest control, which attempts to stop weeds, especially noxious weeds, from competing with desired flora and fauna including domesticated plants and livestock, and in natural settings preventing non native species competing with native species.
A mulch is a layer of material applied to the surface of soil. Reasons for applying mulch include conservation of soil moisture, improving fertility and health of the soil, reducing weed growth and enhancing the visual appeal of the area.
Onopordum acanthium is a flowering plant in the family Asteraceae. It is native to Europe and Western Asia from the Iberian Peninsula east to Kazakhstan, and north to central Scandinavia, and widely naturalised elsewhere, with especially large populations present in the United States and Australia. It is a vigorous biennial plant with coarse, spiny leaves and conspicuous spiny-winged stems.
Polygonum is a genus of about 130 species of flowering plant in the buckwheat and knotweed family Polygonaceae. Common names include knotweed and knotgrass. In the Middle English glossary of herbs Alphita, it was known as ars-smerte. There have been various opinions about how broadly the genus should be defined. For example, buckwheat has sometimes been included in the genus as Polygonum fagopyrum. Former genera such as Polygonella have been subsumed into Polygonum; other genera have been split off.
Asclepias syriaca, commonly called common milkweed, butterfly flower, silkweed, silky swallow-wort, and Virginia silkweed, is a species of flowering plant. It is native to southern Canada and much of the United States east of the Rocky Mountains, excluding the drier parts of the prairies. It is in the genus Asclepias, the milkweeds. It grows in sandy soils as well as other kinds of soils in sunny areas.
In agriculture, a living mulch is a cover crop interplanted or undersown with a main crop, and intended to serve the purposes of a mulch, such as weed suppression and regulation of soil temperature. Living mulches grow for a long time with the main crops, whereas cover crops are incorporated into the soil or killed with herbicides.
Soliva sessilis, one of up to nine species of the genus Soliva, is a low-growing herbaceous annual plant. Its common names include field burrweed, Onehunga-weed, lawn burrweed, lawnweed, and common soliva. It is one of several plants known as bindi weed, bindii, or bindi-eye.
Melilotus albus, known as honey clover, white melilot (UK), Bokhara clover (Australia), white sweetclover (USA), and sweet clover, is a nitrogen-fixing legume in the family Fabaceae. Melilotus albus is considered a valuable honey plant and source of nectar and is often grown for forage. Its characteristic sweet odor, intensified by drying, is derived from coumarin.
In permaculture, sheet mulching is an agricultural no-dig gardening technique that attempts to mimic the natural soil-building process in forests. When deployed properly and in combination with other permaculture principles, it can generate healthy, productive, and low maintenance ecosystems.
Polygonum aviculare or common knotgrass is a plant related to buckwheat and dock. It is also called prostrate knotweed, birdweed, pigweed and lowgrass. It is an annual found in fields and wasteland, with white flowers from June to October. It is widespread across many countries in temperate regions, apparently native to Eurasia and North America, naturalized in temperate parts of the Southern Hemisphere.
Amaranthus tuberculatus, commonly known as roughfruit amaranth, rough-fruited water-hemp, tall waterhemp, or common waterhemp, is a species of flowering plant. It is a summer annual broadleaf with a germination period that lasts several months. Tall waterhemp has been reported as a weed in 40 of 50 U.S. states.
Veronica serpyllifolia, the thyme-leaved speedwell or thymeleaf speedwell, is a perennial flowering plant in the plantain family. It is native to Europe, but can be found elsewhere on most continents as an introduced species.
A weed is a plant considered undesirable in a particular situation, "a plant in the wrong place". Examples commonly are plants unwanted in human-controlled settings, such as farm fields, gardens, lawns, and parks. Taxonomically, the term "weed" has no botanical significance, because a plant that is a weed in one context is not a weed when growing in a situation where it is wanted. In the same way, volunteer crops (plants) are regarded as weeds in a subsequent crop. The term weed is also applied to any plant that grows or reproduces aggressively, or is invasive outside its native habitat.
Scleranthus annuus is a species of flowering plant in the family Caryophyllaceae known by the common names German knotweed and annual knawel. It is native to Europe, Asia, and North Africa, and it is known throughout the rest of the temperate world as an introduced species and a common weed. It grows in many types of habitat, often in disturbed areas.
Panicum repens is a species of grass known by many common names, including torpedograss, creeping panic, panic rampant, couch panicum, wainaku grass, quack grass, dog-tooth grass, and bullet grass. Its exact native range is obscure. Sources suggest that the grass is native to "Africa and/or Asia", "Europe or Australia", "Eurasia", "Australia", "Europe, Asia, and Africa", or other specific regions, including the Mediterranean, Israel, and Argentina. It is present in many places as an introduced species and often a noxious weed. It has been called "one of the world's worst weeds."
Mechanical weed control is a physical activity that inhibits unwanted plant growth. Mechanical, or manual, weed control techniques manage weed populations through physical methods that remove, injure, kill, or make the growing conditions unfavorable. Some of these methods cause direct damage to the weeds through complete removal or causing a lethal injury. Other techniques may alter the growing environment by eliminating light, increasing the temperature of the soil, or depriving the plant of carbon dioxide or oxygen. Mechanical control techniques can be either selective or non-selective. A selective method has very little impact on non-target plants where as a non-selective method affects the entire area that is being treated. If mechanical control methods are applied at the optimal time and intensity, some weed species may be controlled or even eradicated.
Acalypha ostryifolia, sometimes spelled ostryaefolia, is a plant in the family Euphorbiaceae and is commonly known as hophornbeam copperleaf, hornbeam copperleaf, or pineland threeseed mercury, is an annual herb of the copperleaf genus Acalypha. It is a native of North and Central America and is generally considered a weed.
Polygonum majus is a North American species of flowering plant in the buckwheat family known by the common name wiry knotweed. It grows in the western United States and western Canada, from British Columbia south as far as the Sierra Nevada of northwestern Inyo County in California, east as far as Montana. Knotweed is a spreading, wiry annual weed that rarely grows higher than a few inches. The leaves are tiny, oblong, bluish-green, and 14 inches broad and 1 inch long. The flowers are tiny and unobtrusive, whitish-green in colour, and appear in the leaf axils in the fall. Knotweed may grow into a dense mat with a diameter of up to three feet, strangling out ideal grass and plants. The branches of this evergreen plant form a strong, wiry mat that reaches barely a few centimeters above the earth. They appear constantly, and gardeners are always fighting them. We cultivate the soil by tilling and enriching it. We plant our flowers and veggies, but the weeds make the most of our efforts. We believe we've got situation under control, but then we walk around to discover different things growing where we didn't expect it: knotweed sprawls down our walkways and up between our patio's paving stones.
Phyla canescens is a species of perennial herbaceous plant in the family Verbenaceae, native to South America. It has been introduced to Australia as an ornamental plant and low-maintenance lawn, but has become naturalised and is considered a serious environmental weed. It is known by several common names including carpet weed, Condamine couch, Condamine curse, fog fruit, frog fruit, hairy fogfruit, lippia, mat grass and no-mow grass.