Opuntia monacantha

Native to eastern and southern Brazil, Paraguay and Uruguay, this succulent shrub or small tree belongs to the Cactaceae family. Its flattened, glossy stem segments often droop, especially higher on the plant. Yellow flowers may have reddish stripes on their outer segments. The pear-shaped fruit ripens from green to red-purple and has edible pulp, although its surface carries small barbed bristles. Detached stems and even immature fruit can develop into new plants. The species is invasive in Australia, where dense, spiny thickets impede access to pasture and water. Photographed in Bogotá, Colombia.