brilliant purple thistle bloom attract butterflies and humblebee to the garden in outflow and summertime and supply a pet food of birds in summertime and declination . thistle thrive in rough , dry conditions , but not all thistles are considered beneficial . Some thistle are invading weeds that can crowd out native plants .
Milk Thistle
Milk thistle ( Silybum marianum ) can be identified by the clean nervure on the leaves . Milk River thistle is cultivated in Europe and Asia . The seminal fluid are laugh at and eaten or used to make a tea or tint to deal diseases of the liver , gallbladder and kidney . The plant is also sometimes corrode as a vegetable . Though not a fellow member of the thistle ( Circium ) household , milk thistle resemble other thistles in many ways .
Russian Thistle
Russian thistle ( Salsola tragus ) , when dried , forms the Cycloloma atriplicifolium seen along roadsides in some parts of the American West . Russian thistle can grow from 1 to 3 ft tall and up to 5 foot across . As they grow , they become very stiff and spiny . These yearly plants die in wintertime . They dry out and are eventually uprooted , to be blown about by the current of air . Russian thistles also are n’t really thistle . Their flush do n’t resemble thistle at all , but they do have deeply lobed , spiky foliation typical of thistles .
Canadian Thistle
Canadian thistle ( Circium arvense ) is an trespassing weed that distribute rapidly and can invade pastures and gardens . A matured plant can reach up to 4 feet in superlative . The purple heyday are small , but each contains hundreds of seminal fluid that float on the wind , allowing the plant to procreate over a broad stove . The theme of Canadian thistle are very deep , so pout or cutting it is n’t an efficacious way to hold it . The herbicide glyphosate is one effective control , though it may have to be applied more than once to kill the plant .
Bull Thistle
Bull thistle ( Cirsium vulgare ) is a common wayside thistle with dark bluish - green , deep lobed prickly foliage and pinkish - purple blossoms . Like other true thistles , it ’s a biennial , blooming in its second yr . Where it become invasive it can often be controlled by recapitulate mowing before the plant form blossom or germ .
Scotch Thistle
Scotch thistle ( Onopordum acanthium ) was imported into the United States from Europe . It has abrupt , spiny leaves covered with thick , cottony hairs and abstruse majestic blooms . Though originally grown as an ornamental , Scotch thistle has become an invasive mourning band in many areas . Tilling or diligence of glyphosate are two methods of ascendence .
