Nutgrass

Cyperus rotundus is a perennial sedge, up to 140 centimetres tall, native to Africa, southern and central Europe and southern Asia, and called coco-grass, Java grass, nut grass and purple nutsedge. The name nut grass comes from its tubers, which look like nuts but are not botanically nuts. The leaves sprout in ranks of three from the base, the flower stems are triangular in cross-section, and the young rhizomes are white and fleshy before some form dark reddish-brown tubers. The page says it grows on wasteland and in crop fields, preferring dry conditions. It was used in ancient Egypt, Mycenaean Greece and elsewhere as an aromatic and to purify water, and by the Greek physicians Theophrastus, Pliny the Elder and Dioscorides as medicine and perfume. The tubers are a staple carbohydrate for some hunter-gatherers and a famine food in some farming cultures. In traditional Chinese medicine it is considered the primary qi-regulating herb.