The Knot-grass is the Polygonum aviculare, a British weed, low, straggling, and many-jointed, hence its name of Knot-grass. There is no doubt that this is the plant meant, and its connection with a dwarf is explained by the belief, probably derived from some unrecorded character detected by the "doctrine of signatures," that the growth of children could be stopped by a diet of Knot-grass. Steevens quotes Beaumont and Fletcher to this effect, and this will probably explain the epithet "hindering." But there may be another explanation. Johnston tells us that in the north, "being difficult to cut in the harvest time, or to pull in the process of weeding, it has obtained the sobriquet of the Deil's-lingels." From this it may well be called "hindering," just as the Ononis, from the same habit of catching the plough and harrow, has obtained the prettier name of "Rest-harrow."

But though Shakespeare's Knot-grass is undoubtedly the Polygonum, yet the name was also given to another plant, for this cannot be the plant mentioned by Milton—

In this case it must be one of the pasture Grasses, and may be Agrostis stolonifera, as it is said to be in Aubrey's "Natural History of Wilts" (Dr. Prior).