Agrostemma githago, corn campion, corn cockle, crown-of-the-field - European annual having large trumpet-shaped reddish-purple flowers and poisonous seed; a common weed in grainfields and beside roadways; naturalized in America

knawe, knawel, Scleranthus annuus - widely distributed low-growing Eurasian herb having narrow leaves and inconspicuous green flowers

corn spurrey, corn spurry, Spergula arvensis - small European weed with whorled leaves and white flowers

sand spurry, sea spurry, Spergularia rubra - prostrate weedy herb with tiny pink flowers; widespread throughout Europe and Asia on sand dunes and heath and coastal cliffs; naturalized in eastern North America

carpetweed, Indian chickweed, Molluga verticillata - annual prostrate mat-forming weed having whorled leaves and small greenish-white flowers; widespread throughout North America

alligator grass, alligator weed, Alternanthera philoxeroides - prolific South American aquatic weed having grasslike leaves and short spikes of white flowers; clogs waterways with dense floating masses

Barbarea vulgaris, rockcress, rocket cress, Sisymbrium barbarea, yellow rocket - noxious cress with yellow flowers; sometimes placed in genus Sisymbrium

Erysimum cheiranthoides, wormseed mustard - slender yellow-flowered European mustard often troublesome as a weed; formerly used as an anthelmintic

jointed charlock, Raphanus raphanistrum, runch, wild radish, wild rape - Eurasian weed having yellow or mauve or white flowers and podlike fruits

pennycress - any of several plants of the genus Thlaspi

ambrosia, bitterweed, ragweed - any of numerous chiefly North American weedy plants constituting the genus Ambrosia that produce highly allergenic pollen responsible for much hay fever and asthma

thistle - any of numerous plants of the family Compositae and especially of the genera Carduus and Cirsium and Onopordum having prickly-edged leaves

Barnaby's thistle, Centaurea solstitialis, yellow star-thistle - European weed having a winged stem and hairy leaves; adventive in the eastern United States

Canadian fleabane, Conyza canadensis, Erigeron canadensis, horseweed, fleabane - common North American weed with linear leaves and small discoid heads of yellowish flowers; widely naturalized throughout temperate regions; sometimes placed in genus Erigeron

Erechtites hieracifolia, fireweed - an American weedy plant with small white or greenish flowers

Hieracium praealtum, king devil, yellow hawkweed - European hawkweed introduced into northeastern United States; locally troublesome weeds

California dandelion, capeweed, gosmore, Hypochaeris radicata, cat's-ear - European weed widely naturalized in North America having yellow flower heads and leaves resembling a cat's ears

bastard feverfew, Parthenium hysterophorus - tropical American annual weed with small radiate heads of white flowers; adventive in southern United States

bitterweed, bristly oxtongue, oxtongue, Picris echioides, bugloss - widespread European weed with spiny tongue-shaped leaves and yellow flowers; naturalized in United States

Hieracium aurantiacum, orange hawkweed, Pilosella aurantiaca - European hawkweed having flower heads with bright orange-red rays; a troublesome weed especially as naturalized in northeastern North America; sometimes placed in genus Hieracium

Senecio doublasii, threadleaf groundsel - bluish-green bushy leafy plant covered with close white wool and bearing branched clusters of yellow flower heads; southwestern United States; toxic to range livestock

benweed, ragweed, ragwort, Senecio jacobaea, tansy ragwort - widespread European weed having yellow daisylike flowers; sometimes an obnoxious weed and toxic to cattle if consumed in quantity

groundsel, Senecio vulgaris - Eurasian weed with heads of small yellow flowers

cockle-bur, cockle-burr, cocklebur, cockleburr - any coarse weed of the genus Xanthium having spiny burrs

cannabis, ganja, marihuana, marijuana - the most commonly used illicit drug; considered a soft drug, it consists of the dried leaves of the hemp plant; smoked or chewed for euphoric effect

remove, take away, withdraw, take - remove something concrete, as by lifting, pushing, taking off, etc. or remove something abstract; "remove a threat"; "remove a wrapper"; "Remove the dirty dishes from the table"; "take the gun from your pocket"; "This machine withdraws heat from the environment"