- Actites megalocarpus, Dune Thistle;Sonchus asper var megalocarpus Hookf;Sonchus asper var megalocarpa orth var Hookf sensu Hooker, JD 1855;Sonchus megalocarpus Hookf JMBlack;Embergeria megalocarpa Hookf Boulos;Sonchus asper var littoralis JMBlack
- Berkheya rigida, African Thistle;Hamelin Thistle;Stobaea rigida Thunb
- Carduus acanthoides, Spiny plumeless thistle
- Carduus crispus, Welted Thistle;Curly plumeless thistle
- Carduus nutans, Nodding Thistle;Musk Thistle;Carduus macrocephalus;Nodding plumeless thistle;Musk thistle;Nodding Plumeless Thistle;Carduus macrocephalus Desf;Carduus macrolepis Peterm
- Carduus pycnocephalus, Plymouth Thistle;Carduus tenuiflorus auct, non Curtis;Italian plumeless thistle
- Carduus tenuiflorus, Slender Thistle;Carduus pycnocephalus var tenuiflorus (Curtis) Ball;Winged plumeless thistle
- Carlina vulgaris, Carline Thistle;Carline thistle
- Carthamus dentatus, Toothed Thistle;Onobroma dentatum Vahl Spreng;Kentrophyllum dentatum Vahl Tausch
- Carthamus lanatus, Saffron Thistle;Woolly Star Thistle;Yellow Distaff Thistle;Phonus lanatus L Hill;Atractylis lanata L Scop;Carduus lanatus L Brot;Centaurea lanata L Lam & Dc;Heracantha lanata L Hoffmanns & Link;Onobroma lanatum L Bluff & Fingerh;Kentrophyllum lanatum L Dc & Duby;Carduncellus lanatus L Moris;Carthamus creticus L;Heracantha cretica L Hoffmanns & Link;Centaurea cretica L Spreng;Kentrophyllum creticum L Tausch;Kentrophyllum baeticum Boiss & Reut;Carthamus baeticus Boiss & Reut Nyman;Kentrophyllum lanatum var baeticum Boiss & Reut Batt;Downy Safflower;Woolly distaff thistle
- Carthamus leucocaulos, Onobroma leucocaulon Sm Spreng;Kentrophyllum leucocaulon Sm Tausch;Whitestem distaff thistle
- Carthamus oxyacanthus, Jeweled Distaff Thistle;Carthamus oxyacantha M Bieb, orth var;Wild Safflower
- Centaurea solstitialis, Yellow Star-thistle;Leucantha solstitialis (L) Á Löve & D Löve;Yellow Star Thistle;Yellow star-thistle;Yellow Starthistle
- Cirsium acarna, Yellow Plumed Thistle
- Cirsium acaule, Dwarf Thistle;Carduus acaulos L
- Cirsium altissimum, Tall thistle
- Cirsium andersonii, Rose thistle
- Cirsium andrewsii, Franciscan thistle
- Cirsium arizonicum, Arizona thistle
- Cirsium arvense, Perennial Thistle;Creeping thistle;Creeping Thistle;Canada Thistle;Serratula arvensis L;Carduus arvensis L Robson;Cnicus arvensis L Roth;Breea arvensis L Less;Cephalonoplos arvensis L Fourr;Carduus lanatus Roxb ex Willd;Cirsium lanatum Roxb ex Willd Spreng;Canada thistle
- Cirsium barnebyi, Barnebys thistle
- Cirsium brevifolium, Palouse thistle
- Cirsium brevistylum, Clustered thistle
- Cirsium calcareum, Cainville thistle
- Cirsium canescens, Prairie thistle
- Cirsium canovirens, Graygreen thistle
- Cirsium carolinianum, Soft thistle
- Cirsium centaureae, Fringed thistle
- Cirsium ciliolatum, Ashland thistle
- Cirsium clavatum, Fish Lake thistle
- Cirsium crassicaule, Slough thistle
- Cirsium cymosum, Peregrine thistle
- Cirsium discolor, Field thistle
- Cirsium dissectum, Meadow Thistle;Carduus dissectus L
- Cirsium douglasii, Douglas thistle
- Cirsium drummondii, Dwarf thistle
- Cirsium eatonii, Eatons thistle
- Cirsium edule, Indian Thistle;Edible thistle
- Cirsium eriophorum, Woolly Thistle;Carduus eriophorus L;Cirsium eriophorum subsp britannicum Petr
- Cirsium erisithales, Yellow Thistle;Carduus erisithales Jacq
- Cirsium flodmanii, Flodmans thistle
- Cirsium foliosum, Elk thistle
- Cirsium fontinale, Fountain thistle
- Cirsium gilense, Gila thistle
- Cirsium grahamii, Grahams thistle
- Cirsium helenioides, Melancholy Thistle;Carduus heterophyllum;Carduus heterophyllus L;Melancholy thistle;Carduus helenioides L;Carduus helenoides L, orth var;Cirsium heterophyllum (L) Hill
- Cirsium hillii, Hills thistle
- Cirsium hookerianum, White thistle
- Cirsium horridulum, Yellow thistle
- Cirsium hydrophilum, Suisun thistle
- Cirsium japonicum, Japanese thistle
- Cirsium kamtschaticum, Kamchatka thistle
- Cirsium lecontei, Le Contes Thistle;Carduus lecontei (Torr & A Gray) Pollard
- Cirsium loncholepis, La graciosa thistle
- Cirsium longistylum, Longstyle thistle
- Cirsium mexicanum, Mexican thistle
| - Cirsium mohavense, Mojave thistle
- Cirsium murdockii, Murdocks thistle
- Cirsium muticum, Swamp thistle
- Cirsium neomexicanum, New Mexico thistle
- Cirsium nuttallii, Nuttalls Thistle;Carduus nuttallii (Dc) Pollard
- Cirsium occidentale, Cobwebby thistle
- Cirsium ochrocentrum, Yellowspine thistle
- Cirsium oleraceum, Cabbage Thistle;Cnicus oleraceus L
- Cirsium ownbeyi, Ownbeys thistle
- Cirsium pallidum, Pale thistle
- Cirsium palustre, Marsh Thistle;Carduus palustris L;Marsh thistle
- Cirsium parryi, Parrys thistle
- Cirsium peckii, Steen Mountain thistle
- Cirsium perplexans, Rocky Mountain thistle
- Cirsium pitcheri, Sand dune thistle
- Cirsium praeteriens, Palo Alto thistle
- Cirsium pulcherrimum, Wyoming thistle
- Cirsium pumilum, Pasture thistle
- Cirsium quercetorum, Alameda County thistle
- Cirsium remotifolium, Fewleaf thistle
- Cirsium repandum, Sandhill Thistle;Carduus repandus (Michx) Pers
- Cirsium rhothophilum, Surf thistle
- Cirsium rivulare, Brook Thistle
- Cirsium rothrockii, Rothrocks thistle
- Cirsium rydbergii, Rydbergs thistle
- Cirsium scabrum, Rough thistle
- Cirsium scapanolepis, Mountain slope thistle
- Cirsium scariosum, Meadow thistle
- Cirsium scopulorum, Mountain thistle
- Cirsium subniveum, Jackson Hole thistle
- Cirsium texanum, Texas thistle
- Cirsium tuberosum, Tuberous Thistle;Carduus tuberosus L
- Cirsium turneri, Cliff thistle
- Cirsium undulatum, Wavyleaf thistle
- Cirsium virginense, Virgin thistle
- Cirsium virginianum, Virginia Thistle;Carduus virginianus L;Cirsium revolutum (Small) Petr
- Cirsium vulgare, Spear Thistle;Scotch Thistle;Bull Thistle;Black Thistle;Carduus vulgaris Savi;Carduus lanceolatus L;Cirsium lanceolatum L Scop;Cnicus lanceolatus L Willd;Cirsium lanceolatum (L) Scop non Hill;Bull thistle
- Cirsium wheeleri, Wheelers thistle
- Cnicus benedictus, Blessed Thistle;Centaurea benedicta (L) L;Cirsium pugnax Sommier & Levier
- Lactuca serriola, Compass Plant;Prickly Lettuce;Milk Thistle;Lactuca scariola L;Prickly lettuce;Wild Lettuce, Milk Lettuce, Milk Thistle, Compass Plant, Wild Opium, English Thistle, Weed Milk Thistle, Horse Thistle
- Notobasis syriaca, Syrian Thistle
- Onopordum acanthium, Cotton Thistle;Scotch Thistle;Scotch cottonthistle
- Onopordum illyricum, Illyrian Thistle;Illyrian cottonthistle
- Onopordum nervosum, Reticulate Thistle
- Salsola collina, Slender Russian thistle
- Salsola kali, Russian thistle;Salsola caroliniana
- Salsola paulsenii, Barbwire Russian thistle
- Salsola soda, Oppositeleaf Russian thistle
- Salsola tragus, Prickly Russian thistle;Russian Thistle;Tumbleweed
- Salsola vermiculata, Shrubby Russian thistle;Mediterranean Saltwort
- Scolymus hispanicus, Golden Thistle;Scolymus grandiflorus;Common goldenthistle;Common Goldenthistle;Scolymus grandiflorus Desf
- Silybum marianum, Variegated Thistle;Milk Thistle;Holly Thistle;Ladys Thistle;St Marys Thistle;Bull Thistle;Spotted Milk Thistle;Spotted Thistle;Virgin Marys Thistle;Carduus marianus L;Mariana mariana L Hill;Centaurea dalmatica;Blessed milkthistle
- Solanum rostratum, Buffalo Burr;Pincushion Nightshade;Texas Thistle;Mexican Thistle;Colorado Burr;Solanum heterandrum Pursh;Nycterium rostratum Dunal Link;Androcera rostrata Dunal Rydb;Buffalo-bur;Solanum cornutum auct non Lam;Buffalobur nightshade;Colorado Bur;Texas Sandbur;Prickly Night-Shade;Beaked Nightshade;Kansas Thistle;Sand Bur
- Sonchus asper, Rough Sow-thistle;Prickly Sow-thistle;Rough Sowthistle;Rough Milk Thistle;Spiny Sowthistle;Prickly Sowthistle;Prickly Sow-Thistle;Sonchus oleraceus var asper L;Sonchus asper subsp glaucescens (Jord) Ball;Spiny sowthistle;Sonchus oleraceus var asper
- Sonchus oleraceus, Smooth Sow-thistle;Common sowthistle;Smooth Sow-Thistle;Common Sow-Thistle;Annual Sow-Thistle;Hares Lettuce;Colewort;Milk Thistle;Thistle Milkweed;Milky Tassel;Swinies
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