water-clover (Marsilea quadrifolia)
Water-clover may be found in ponds, streams and roadside ditches. Resembling four-leaf clovers on long, thin stalks, these aquatic plants are ferns. Water-clover is used in water gardens and horticultural plantings and has escaped to the wild. It competes with native plants in both aquatic and moist terrestrial habitats. Water-clover has been established in the northeastern United States for more than 100 years. The introduced range of this European species includes scattered locations throughout Illinois.