silverleaf nightshade

It is a perennial 10 cm (3.9 in) to 1 m in height. The stems are covered with nettle-like spines less than 0.5 cm (0.20 in) long, ranging from very few on some plants to very dense on others. Leaves and stems are covered with downy hairs (trichomes) that lie against and hide the surface, giving a silvery or grayish appearance. The leaves are up to 15 cm long and 0.5 to 2.5 cm wide, with shallowly waved edges, which distinguish it from the closely related Carolina Horsenettle (S. carolinense), which has wider, more deeply indented leaves. The flowers, appearing from April to August, have five petals united to form a star, ranging from blue to pale lavender or occasionally white; five yellow stamens and a pistil form a projecting center. The plant produces glossy yellow, orange, or red berries that last all winter and may turn brown as they dry.

It can grow in poor soil with very little water. It spreads by rhizomes as well as seeds, and is common in disturbed habitats. It is very hard to control, as root stocks less than 1 cm long can regenerate into plants. Its distribution around the globe is in the regions of Mediterranean, South Australia, South Africa, US, Mexico and South America. In the US, its range is from Kansas south to Louisiana, and west through the Mexican-border states of the United States into and in Mexico. In South America it is found in Uruguay, Argentina, and Chile. It may have originated in North America and been accidentally introduced to South America or the reverse. It is considered a noxious weed in 21 U.S. states and in countries such as Australia, Egypt, Greece, India, Israel, Italy, South Africa, and Zimbabwe. In a 15-year research study it was indicated that important factors for its expansion are: Elevation of 0-100m, soils with fine texture and in subsoil of medium water availability, soils with high base saturation of the topsoil and low topsoil organic carbon. …