Horse nettle as a troublesome weed in Iowa. Two other troublesome weeds. Potato scab.
Horse Nettle is a deep-rooting perennial, propagating freely by its underground rootstocks, the running roots are often three feet long; stem from one to two feet high, somewhat straggling, half shrubby at the base; stem hairy or merely roughish with minute hairs which are star-shaped, also armed with stout subulate yellowish prickles which are usually numerous; leaves oblong or sometimes ovate, obtusely sinuate, toothed or lobed or deeply cut, two to four inches long. The flowers are borne in what are called racemes, which later become one-sided; the outer part of the flower, the calyx, consists of slender lobes, the corolla is light blue or white, an inch or less in diameter. The flowers are followed by the yelow globose berries, half to three-quarters of an inch in diameter. The small seeds are yellowish, a little less than one-twelfth of an inch long, minutely roughened.