| alpine knapweed |
Centaurea nigrescens |
3 |
| American burnweed |
Erechtites hieraciifolius |
3 |
| annual bursage |
Ambrosia acanthicarpa |
4 |
| annual fleabane |
Erigeron annuus |
1 |
| annual sowthistle |
Sonchus oleraceus |
2 |
| annual wormwood |
Artemisia annua |
1 |
| Australian burnweed |
Erechtites minimus |
3 |
| biennial wormwood |
Artemisia biennis |
4 |
| big sagebrush |
Artemisia tridentata |
3 |
| bitter lettuce |
Lactuca virosa |
6 |
| black knapweed |
Centaurea nigra |
2 |
| blessed milkthistle |
Silybum marianum |
5 |
| blessed thistle |
Cnicus benedictus |
2 |
| blue lettuce |
Lactuca tatarica var. pulchella |
3 |
| brassbuttons |
Cotula coronopifolia |
3 |
| bristly hawksbeard |
Crepis setosa |
3 |
| bristly oxtongue |
Helminthotheca echioides |
4 |
| bull cottonthistle |
Onopordum tauricum |
1 |
| bull thistle |
Cirsium vulgare |
4 |
| bur beggarticks |
Bidens tripartita |
3 |
| California mugwort |
Artemisia douglasiana |
3 |
| Canada thistle |
Cirsium arvense |
4 |
| cape ivy |
Delairea odorata |
6 |
| capeweed |
Arctotheca calendula |
5 |
| cardoon |
Cynara cardunculus |
3 |
| chicory |
Cichorium intybus |
4 |
| common cocklebur |
Xanthium strumarium |
4 |
| common crupina |
Crupina vulgaris |
6 |
| common groundsel |
Senecio vulgaris |
2 |
| common ragweed |
Ambrosia artemisiifolia |
4 |
| common salsify |
Tragopogon porrifolius |
3 |
| common sunflower |
Helianthus annuus |
2 |
| common tansy |
Tanacetum vulgare |
5 |
| common tarweed |
Centromadia pungens ssp. pungens |
3 |
| common yarrow |
Achillea millefolium |
4 |
| corn chamomile |
Anthemis arvensis |
3 |
| cornflower |
Centaurea cyanus |
3 |
| Coulter's horseweed |
Laennecia coulteri |
4 |
| croftonweed |
Ageratina adenophora |
3 |
| curlycup gumweed |
Grindelia squarrosa var. serrulata |
4 |
| cutleaf burnweed |
Erechtites glomeratus |
4 |
| dandelion |
Taraxacum officinale |
3 |
| devils beggarticks |
Bidens frondosa |
4 |
| diffuse knapweed |
Centaurea diffusa |
5 |
| English daisy |
Bellis perennis |
2 |
| feverfew |
Tanacetum parthenium |
4 |
| field marigold |
Calendula arvensis |
2 |
| Fitch's tarweed |
Hemizonia fitchii |
4 |
| giant ragweed |
Ambrosia trifida |
3 |
| glandular Cape marigold |
Dimorphotheca sinuata |
2 |
| Great Valley gumweed |
Grindelia camporum var. camporum |
2 |
| hairy beggarticks |
Bidens pilosa |
5 |
| hairy cat's ear |
Hypochaeris radicata |
4 |
| hairy fleabane |
Conyza bonariensis |
4 |
| hairy galinsoga |
Galinsoga quadriradiata |
2 |
| horseweed |
Conyza canadensis |
4 |
| Italian hawksbeard |
Crepis bursifolia |
2 |
| Italian plumeless thistle |
Carduus pycnocephalus |
4 |
| Jersey cudweed |
Pseudognaphalium luteoalbum |
4 |
| Kellogg's tarweed |
Deinandra kelloggii |
2 |
| lawn burweed |
Soliva sessilis |
2 |
| lesser hawkbit |
Leontodon taraxacoides |
2 |
| Malta starthistle |
Centaurea melitensis |
4 |
| Maximilian sunflower |
Helianthus maximiliani |
1 |
| meadow hawkweed |
Hieracium caespitosum |
1 |
| Mexican brassbuttons |
Cotula mexicana |
1 |
| musk thistle |
Carduus nutans |
5 |
| North African knapweed |
Centaurea diluta |
2 |
| orange hawkweed |
Hieracium aurantiacum |
3 |
| oxeye daisy |
Leucanthemum vulgare |
3 |
| pappose tarweed |
Centromadia parryi ssp. rudis |
3 |
| peregrine thistle |
Cirsium cymosum |
2 |
| pineapple-weed |
Matricaria discoidea |
2 |
| poverty sumpweed |
Iva axillaris |
4 |
| prickly lettuce |
Lactuca serriola |
4 |
| purple cudweed |
Gamochaeta purpurea |
2 |
| purple starthistle |
Centaurea calcitrapa |
4 |
| redpurple ragwort |
Senecio elegans |
3 |
| rush skeletonweed |
Chondrilla juncea |
6 |
| Russian knapweed |
Rhaponticum repens |
5 |
| Scotch thistle |
Onopordum acanthium |
3 |
| seepwillow |
Baccharis salicifolia |
3 |
| slender aster |
Symphyotrichum divaricatum |
6 |
| slenderflower thistle |
Carduus tenuiflorus |
2 |
| smallflower galinsoga |
Galinsoga parviflora |
3 |
| smooth cat's ear |
Hypochaeris glabra |
3 |
| smooth hawksbeard |
Crepis capillaris |
4 |
| snowy thistle |
Cirsium occidentale var. candidissimum |
2 |
| southern brassbuttons |
Cotula australis |
2 |
| spiny cocklebur |
Xanthium spinosum |
2 |
| spiny plumeless thistle |
Carduus acanthoides |
3 |
| spiny sowthistle |
Sonchus asper |
3 |
| spotted knapweed |
Centaurea stoebe ssp. micranthos |
6 |
| squarrose knapweed |
Centaurea virgata |
4 |
| stinking chamomile |
Anthemis cotula |
3 |
| stinkwort |
Dittrichia graveolens |
4 |
| strawflower |
Helichrysum petiolare |
4 |
| sulphur knapweed |
Centaurea sulphurea |
3 |
| tall fleabane |
Conyza floribunda |
3 |
| tall lettuce |
Lactuca canadensis |
2 |
| tansy ragwort |
Senecio jacobaea |
3 |
| telegraphplant |
Heterotheca grandiflora |
5 |
| threeray tarweed |
Hemizonia lobbii |
1 |
| virgate tarweed |
Holocarpha virgata |
4 |
| wavyleaf thistle |
Cirsium undulatum |
3 |
| western marsh cudweed |
Gnaphalium palustre |
2 |
| western ragweed |
Ambrosia psilostachya |
3 |
| western salsify |
Tragopogon dubius |
4 |
| whiteplume wirelettuce |
Stephanomeria exigua ssp. coronaria |
3 |
| willowleaf lettuce |
Lactuca saligna |
4 |
| woodland groundsel |
Senecio sylvaticus |
5 |
| woolly distaff thistle |
Carthamus lanatus |
4 |
| yellow chamomile |
Anthemis tinctoria |
3 |
| yellow starthistle |
Centaurea solstitialis |
3 |
| yellowspine thistle |
Cirsium ochrocentrum |
3 |
