#weed any plant that crowds out cultivated plants
exclusion: #cultivated_plant
supertype: #vascular_plant__tracheophyte green plant having a vascular system: ferns, gymnosperms, angiosperms
subtype: #corn_cockle__corn_campion__crown-of-the-field__Agrostemma_githago European annual having large trumpet-shaped reddish-purple flowers and poisonous seed; a common weed in grainfields and beside roadways; naturalized in America
subtype: #knawel__knawe__Scleranthus_annuus widely distributed low-growing Eurasian herb having narrow leaves and inconspicuous green flowers
subtype: #corn_spurry__corn_spurrey__Spergula_arvensis small European weed with whorled leaves and white flowers
subtype: #sand_spurry__sea_spurry__seaspurry__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
subtype: #carpetweed__Indian_chickweed__Molluga_verticillata annual prostrate mat-forming weed having whorled leaves and small greenish-white flowers; widespread throughout North America
subtype: #alligator_weed__alligatorweed__alligatorgras__Alternanthera_philoxeroides prolific South American aquatic weed having grasslike leaves and short spikes of white flowers; clogs waterways with dense floating masses
subtype: #yellow_rocket__rockcress__rockcres__rocketcres__barbareavulgari__Sisymbrium_barbarea noxious cress with yellow flowers; sometimes placed in genus Sisymbrium
subtype: #wormseed_mustard__Erysimum_cheiranthoides slender yellow-flowered European mustard often troublesome as a weed; formerly used as an anthelmintic
subtype: #jointed_charlock__jointedcharlock__wild_radish__wild_rape__runch__Raphanus_raphanistrum Eurasian weed having yellow or mauve or white flowers and podlike fruits
subtype: #pennycress any of several plants of the genus Thlaspi
subtype: #field_pennycress__French_weed__fanweed__pennygras__mithridate_mustard__Thlaspi_arvense foetid Eurasian weed having round flat pods; naturalized throughout North America
subtype: #ragweed__ambrosia__bitterweed any of numerous chiefly North American weedy plants constituting the genus Ambrosia that produce highly allergenic pollen responsible for much hay fever and asthma
subtype: #common_ragweed__Ambrosia_artemisiifolia annual weed with finely divided foliage and spikes of green flowers; common in North America; introduced elsewhere accidentally
subtype: #great_ragweed__greatragweed__Ambrosia_trifida a coarse annual with some leaves deeply and palmately 3-cleft or 5-cleft
subtype: #western_ragweed__westernragweed__perennial_ragweed__perennialragweed__Ambrosia_psilostachya coarse perennial ragweed with creeping roots of dry barren lands of southwestern United States and Mexico
subtype: #thistle any of numerous plants of the family Compositae and especially of the genera Carduus and Cirsium and Onopordum having prickly-edged leaves
subtype: #welted_thistle__Carduus_crispus European biennial introduced in North America having flower heads in crowded clusters at ends of spiny-winged branches
subtype: #musk_thistle__nodding_thistle__noddingthistle__Carduus_nutans Eurasian perennial naturalized in eastern North America having very spiny white cottony foliage and nodding musky crimson flower heads; valuable source of nectar
subtype: #carline_thistle__carlinethistle a thistle of the genus Carlina
subtype: #stemless_carline_thistle__Carlina_acaulis stemless perennial having large flowers with white or purple-brown florets nestled in a rosette of long spiny leaves hairy beneath; of alpine regions of southern and eastern Europe
subtype: #common_carline_thistle__Carlina_vulgaris Eurasian thistle growing in sand dunes and dry chalky soils
subtype: #plume_thistle__plumethistle__plumed_thistle any of numerous biennial to perennial herbs with handsome purple or yellow or occasionally white flower heads
subtype: #Canada_thistle__creeping_thistle__Cirsium_arvense European thistle naturalized in United States and Canada where it is a pernicious weed
subtype: #woolly_thistle__Cirsium_flodmanii thistle of western North America having white woolly leaves
subtype: #European_woolly_thistle__Cirsium_eriophorum woolly thistle of western and central Europe and Balkan Peninsula
subtype: #brook_thistle__brookthistle__Cirsium_rivulare of central and southwestern Europe
subtype: #bull_thistle__boar_thistle__spear_thistle__spearthistle__Cirsium_vulgare__Cirsium_lanceolatum European thistle with rather large heads and prickly leaves; extensively naturalized as a weed in the United States
subtype: #field_thistle__fieldthistle__Cirsium_discolor stout North American thistle with purplish-pink flower heads
subtype: #melancholy_thistle__Cirsium_heterophylum__Cirsium_helenioides perennial stoloniferous thistle of northern Europe with lanceolate basal leaves and usually solitary heads of reddish-purple flowers
subtype: #blessed_thistle__sweet_sultan__sweetsultan__Cnicus_benedictus annual of Mediterranean to Portugal having hairy stems and minutely spiny-toothed leaves and large heads of yellow flowers
subtype: #cotton_thistle__woolly_thistle__Scotch_thistle__Onopordum_acanthium__Onopordon_acanthium biennial Eurasian white hairy thistle having pale purple flowers; naturalized in North America
subtype: #golden_thistle any of several spiny Mediterranean herbs of the genus Scolymus having yellow flower heads
subtype: #Spanish_oyster_plant__Scolymus_hispanicus a golden thistle of southwestern Europe cultivated for its edible sweet roots and edible leaves and stalks; its yellow flowers are used as a substitute for saffron
subtype: #Barnaby's_thistle__yellow_star-thistle__Centaurea_solstitialis European weed having a winged stem and hairy leaves; adventive in the eastern United States
subtype: #horseweed__Canadian_fleabane__fleabane__Conyza_canadensis__Erigeron_canadensis common North American weed with linear leaves and small discoid heads of yellowish flowers; widely naturalized throughout temperate regions; sometimes placed in genus Erigeron
subtype: #Erechtites_hieracifolia__fireweed an American weedy plant with small white or greenish flowers
subtype: #king_devil__yellow_hawkweed__Hieracium_praealtum European hawkweed introduced into northeastern United States; locally troublesome weeds
subtype: #California_dandelion__cat's-ear__cat'sear__capeweed__gosmore__Hypochaeris_radicata European weed widely naturalized in North America having yellow flower heads and leaves resembling a cat's ears
subtype: #bastard_feverfew__bastardfeverfew__Parthenium_hysterophorus tropical American annual weed with small radiate heads of white flowers; adventive in southern United States
subtype: #bristly_oxtongue__bristlyoxtongue__bitterweed__bugloss__Picris_echioides widespread European weed with spiny tongue-shaped leaves and yellow flowers; naturalized in United States
subtype: #orange_hawkweed__Pilosella_aurantiaca__Hieracium_aurantiacum 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
subtype: #threadleaf_groundsel__Senecio_doublasii 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
subtype: #tansy_ragwort__tansyragwort__ragwort__ragweed__benweed__Senecio_jacobaea widespread European weed having yellow daisylike flowers; sometimes an obnoxious weed and toxic to cattle if consumed in quantity
subtype: #groundsel__Senecio_vulgaris Eurasian weed with heads of small yellow flowers
subtype: #cocklebur any coarse weed of the genus Xanthium having spiny burrs
subtype: #nettle any of numerous plants having stinging hairs that cause skin irritation on contact (especially of the genus Urtica or family Urticaceae)
subtype: #stinging_nettle__Urtica_dioica perennial Eurasian nettle established in North America having broad coarsely toothed leaves with copious stinging hairs
subtype: #Roman_nettle__Urtica_pipulifera annual European nettle with stinging foliage and small clusters of green flowers
subtype: #wood_nettle__Laportea_canadensis American perennial herb found in rich woods and provided with stinging hairs; provides fibers used for textiles
subtype: #richweed__clearweed__dead_nettle__Pilea_pumilla a plants of the genus Pilea having drooping green flower clusters and smooth translucent stems and leaves
subtype: #artillery_plant__artilleryplant__Pilea_microphylla tropical American stingless nettle that discharges its pollen explosively
subtype: #friendship_plant__panamica__panamiga__Pilea_involucrata low stingless nettle of Central and South America having velvety brownish-green toothed leaves and clusters of small green flowers
subtype: #tumbleweed any plant that breaks away from its roots in autumn and is driven by the wind as a light rolling mass
subtype: #wild_parsnip__madnep biennial weed in Europe and America having large pinnate leaves and yellow flowers and a bitter and somewhat poisonous root; the ancestor of cultivated parsnip
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