Thistle Plant
Facts About the Thistle Plant
The thistle plant has a bad reputation in the United States. These are basically a weed species, and they came originally from Europe, eventually spreading into Missouri and surrounding states.
Some weeds are more harmful to the ecology of an area than others, and these are called noxious weeds. The thistle plant is one of these, including Scotch, musk and Canadian thistles. These plants, along with teasels of the cutleaf variety, are regulated by law in some Midwestern states, because they spread so easily and bring harm to the environment.
There are some thistles that are not considered as serious as the thistles mentioned above. Every thistle plant is not a dangerous weed, so you need to make sure that you're removing the correct weeds, if you try to eradicate them. You will probably want to find a book that will help you identify the harmful plants from the benign ones, or ask your extension agent.
The leaves of the bull thistle plant become longer as the plant grows older, and each stem is tipped with a stiff, long spine. You may find hairs on the tops or bottoms of leaves. The flowers of a bull thistle plant are close in color and size to the flowers of a musk thistle, but the bull thistle has hair that is more like a cob web. It also sports bracts tipped with spines below the flower. Bull thistle is a common thistle in the Midwest and can be found alongside roads or sometimes in fields, if they are not properly maintained.
The musk thistle plant is sometimes called a nodding thistle, since it has large heads of flowers that bend over when the wind blows them. Young plants have pale waxy green leaves with margins that are shallowly lobed, and hold prickles that are irregular in shape. As the plants grow, their leaves become cut more deeply, and the margins will become tipped with sharp, stiff spines. The tissue of the leaves becomes more glossy as the plant ages, and the only hair is usually found on the main veins. The flower head will develop many bracts that are spine-tipped, and it is usually purple or pink in color, although you may see occasional white flowers as well. The flowers are about 2 inches across. In most Midwestern states, the musk thistle plant is a problem in pastures and near roads, and it is categorized as a noxious weed.
The Scotch thistle plant has large sized leaves that are coarsely lobed with spines. This thistle has dense hair on its leaves and stems, giving it a gray or blue cast. It is also known as a cotton thistle. This plant develops large wings that are formed where the bases of the leaves are attached. The flowers are one to two inches wide, and may be found in clusters or as single flowers. They are purple-red in color. This is one of the least common of the thistles in the Midwest states.