Bromus tectorum, known as downy brome, drooping brome or cheatgrass, is a winter annual grass native to Europe, southwestern Asia, and northern Africa, but has become invasive in many other areas. It now is present in most of Europe, southern Russia, Japan, South Africa, Australia, New Zealand, Iceland, Greenland, North America and western Central Asia. In the eastern US B. tectorum is common along roadsides and as a crop weed, but usually does not dominate an ecosystem. It has become a dominant species in the Intermountain West and parts of Canada, and displays especially invasive behavior in the sagebrush steppe ecosystems where it has been listed as noxious weed. B. tectorum often enters the site in an area that has been disturbed, and then quickly expands into the surrounding area through its rapid growth and prolific seed production.
Arrhenatherum, commonly called oat-grass or button-grass, is a genus of Eurasian and North African plants in the grass family.
Spartina is a genus of plants in the grass family, frequently found in coastal salt marshes. Species in this genus are commonly known as cordgrass or cord-grass, and are native to the coasts of the Atlantic Ocean in western and southern Europe, north-western and southern Africa, the Americas and the islands of the southern Atlantic Ocean; one or two species also occur on the western coast of North America and in freshwater habitats inland in the Americas. The highest species diversity is on the east coasts of North and South America, particularly Florida. They form large, often dense colonies, particularly on coastal salt marshes, and grow quickly. The species vary in size from 0.3–2 m tall. Many of the species will produce hybrids if they come into contact.
Centaurea diffusa, also known as diffuse knapweed, white knapweed or tumble knapweed, is a member of the genus Centaurea in the family Asteraceae. This species is common throughout western North America but is not actually native to the North American continent, but to the eastern Mediterranean.
Sporobolus alterniflorus, or synonymously known as Spartina alterniflora, the smooth cordgrass, saltmarsh cordgrass, or salt-water cordgrass, is a perennial deciduous grass which is found in intertidal wetlands, especially estuarine salt marshes. It has been reclassified as Sporobolus alterniflorus after a taxonomic revision in 2014, but it is still common to see Spartina alterniflora and in 2019 an interdisciplinary team of experts coauthored a report published in the journal Ecology supporting Spartina as a genus. It grows 1–1.5 m tall and has smooth, hollow stems that bear leaves up to 20–60 cm long and 1.5 cm wide at their base, which are sharply tapered and bend down at their tips. Like its relative saltmeadow cordgrass S. patens, it produces flowers and seeds on only one side of the stalk. The flowers are a yellowish-green, turning brown by the winter. It has rhizoidal roots, which, when broken off, can result in vegetative asexual growth. The roots are an important food resource for snow geese. It can grow in low marsh as well as high marsh, but it is usually restricted to low marsh because it is outcompeted by salt meadow cordgrass in the high marsh. It grows in a wide range of salinities, from about 5 psu to marine, and has been described as the "single most important marsh plant species in the estuary" of Chesapeake Bay. It is described as intolerant of shade.
Sporobolus anglicus is a hybrid-derived species of cordgrass that originated in southern England in about 1870 and is a neonative species in Britain. It was reclassified as Sporobolus anglicus after a taxonomic revision in 2014, but Spartina anglica is still in common usage. It is an allotetraploid species derived from the hybrid Sporobolus × townsendii, which arose when the European native cordgrass Sporobolus maritimus hybridised with the introduced American Sporobolus alterniflorus.
Melilotus officinalis, known as sweet yellow clover, yellow melilot, ribbed melilot and common melilot, is a species of legume native to Eurasia and introduced in North America, Africa, and Australia.
Melilotus albus, known as honey clover, white melilot (UK), Bokhara clover (Australia), white sweetclover (US), 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.
Aegilops triuncialis, or barbed goatgrass, is a grass species of the family Poaceae. It is a winter annual native to many areas in Eastern and Mediterranean Europe and Western Asia. It is considered an introduced, invasive species in North America, mainly in the Western coast of the United States. In its native lands, the grass thrives in mainly rocky, serpentine soil, but also does well in grasslands and ruderal/disturbed ground as well as oak woodlands.
Arrhenatherum elatius is a species of flowering plant in the grass family Poaceae, commonly known as false oat-grass, and also bulbous oat grass, tall oat-grass, tall meadow oat, onion couch and tuber oat-grass. It is native throughout Europe, and also western and southwestern Asia, and northwestern Africa. This tufted grass is sometimes used as an ornamental grass and is sometimes marketed as "cat grass".
Microstegium vimineum, commonly known as Japanese stiltgrass, packing grass, or Nepalese browntop, is an annual grass that is common in a wide variety of habitats and is well adapted to low light levels. It has become an invasive species throughout parts of the world, most notably North America.
A weed is a plant considered undesirable in a particular situation, growing where it conflicts with human preferences, needs, or goals. Plants with characteristics that make them hazardous, aesthetically unappealing, difficult to control in managed environments, or otherwise unwanted in farm land, orchards, gardens, lawns, parks, recreational spaces, residential and industrial areas, may all be considered weeds. The concept of weeds is particularly significant in agriculture, where the presence of weeds in fields used to grow crops may cause major losses in yields. Invasive species, plants introduced to an environment where their presence negatively impacts the overall functioning and biodiversity of the ecosystem, may also sometimes be considered weeds.
Taeniatherum is a genus of Eurasian and North African plants in the grass family.
Torilis japonica, the erect hedgeparsley, upright hedge-parsley or Japanese hedge parsley, is a herbaceous flowering plant species in the celery family Apiaceae. Japanese hedge parsley is considered both an annual and biennial plant depending on the biogeographical location. This means Japanese hedge parsley can complete its life cycle in either one or two growing seasons depending on habitat. Japanese hedge parsley is typically found in areas with disturbed soils, pastures, margins, open woodland, near waste sites, or right-of-way habitats. It can withstand a variety of habitats, thriving in partial and full shaded areas, but also withstanding habitats with full sunlight penetration. It is considered an aggressive invasive species in North America; invading a wide range of habitats due to its environmental tolerance and tendency to outcompete native vegetation. This species is considered a threat in several areas that causes problems relating to overall environmental health and stability. Aside from its environmental implications, T. japonica has potential to fight several cancers through a terpene it produces called Torilin, extracted from its fruits.
Sporobolus foliosus is a species of grass known by the common name California cordgrass. It was reclassified from Spartina foliosa after a taxonomic revision in 2014. It is native to the salt marshes and mudflats of coastal California and Baja California, especially San Francisco Bay. It is a perennial grass growing from short rhizomes. It produces single stems or clumps of thick, fleshy stems that grow up to 1.5 meters tall. They are green or purple-tinged. The long, narrow leaves are flat or rolled inward. The inflorescence is a narrow, dense, spike-like stick of branches appressed together, the unit reaching up to 25 centimeters long. The lower spikelets are sometimes enclosed in the basal sheaths of upper leaves.
Privets are any of a number of shrubs or trees in the genus Ligustrum, many of which are invasive. The genus contains about 50 species native to the Old World and Australasia. Many members of the genus are grown as ornamental plants in parts of the world.
Centaurea stoebe, the spotted knapweed or panicled knapweed, is a species of Centaurea native to eastern Europe, although it has spread to North America, where it is considered an invasive species. It forms a tumbleweed, helping to increase the species' reach, and the seeds are also enabled by a feathery pappus.
Garlic mustard was introduced to North America as a culinary herb in the 1860s and it is considered an invasive species in much of North America. As of 2020 it has been documented in most of the Eastern United States and Canada, with scattered populations in the west. It is listed as a noxious or restricted plant in the following states: Alabama, Connecticut, Massachusetts, Minnesota, New Hampshire, Oregon, Vermont, and Washington. A current map of its distribution in the United States can be found at the Early Detection and Distribution Mapping System (EDDmapS).
Euphorbia virgata, commonly known as leafy spurge, wolf's milk leafy spurge, or wolf's milk is a species of spurge native to Europe and Asia, and introduced in North America, where it is an invasive species.
Nonnative grasses that are invasive in Brazil include Arundo donax, Rottboellia cochinchinensis, Cortaderia selloana, Nassella neesiana, Spartina densiflora, and Spartina alterniflora. These species have been identified and are being managed by the Ministry of Environment and Forest.
