The Pasture or Fragrant Thistle, from 1 to 3 feet tall, usually has only one broad terminal head of fragrant purple flowers. The Canada Thistle, so-called because it was introduced into Canada from England, is the most noxious weed in our northern states. Seldom more than 3 feet tall, with many branches and deeply cut, very prickly, crinkled leaves, it bears numerous lavender, pink or whitish flowers. It is also called the Creeping Thistle because it spreads rapidly by long rootstocks, as well as by windborne seeds, and forms large patches that crowd out grasses, hay, and grain crops. In many states there are severe penalties for letting it ripen or for selling seeds which include seeds of this thistle.
Most weeds have some virtue.
This outlaw has none. Argonne National Laboratory, Division of Educational Programs, Harold Myron, Ph.D., Division Director.