Reinforced concrete is perhaps the most characteristic component of modern building. Yet this invention was not the work of an architect or engineer, but of a French gardener, Joseph Monier, who in 1867, having studied the skeletal structure of plants, converted some of their patterns into steel. The skeleton of a dead saguaro cactus, for example, closely resembles the reinforcing cage of a ferro-concrete column. This cactus also has a pleated outer skin, which marvellously expands to store water against periods of drought. The fibrous material of many other plant skeletons also share the same steely characteristics of elasticity and resilience. It is these for instance that enable a corn stalk, standing 5 ft (1.5 m) high though less than 1/2 in (13 mm) thick, to bear the weight of the plant's head while it whips back and forth at the behest of the wind.