Horticulture/Cyperus esculentus

Cyperus esculentus (Chufa Sedge, Yellow Nutsedge, Tigernut Sedge, Earthalmond) is a species of sedge native to warm temperate to subtropical regions of the Northern Hemisphere. Some cultivars are grown for the "nuts" (root tubers), but it is most frequently encountered as a weed of lawns and gardens, and can be easily spotted in lawns two or three days after mowing because it regrows much faster than most turf grasses.

Description
Yellow nutsedge is a perennial, grass-like plant, growing to 90 cm tall, with solitary stems arising from small tubers. The stems are triangular in section, and bear slender leaves 3–10 mm wide. The flowers of the plant are distinctive, with a cluster of flat oval seeds surrounded by four hanging leaves positioned 90 degrees from each other. The plant foliage is very tough and fibrous, and is often mistaken for a grass.

The root system can be extensive, with tubers and roots being interconnected to each other to a depth of 50 cm or more. The tubers are connected by fragile roots that are extremely prone to snapping when pulled on, making the plant extremely difficult to remove with its entire root system intact.

Uses and cultivation
The tubers are edible, with a slightly sweet, nutty flavour, compared to the more bitter tasting tuber of the related Cyperus rotundus (Purple Nutsedge). They are quite hard and are generally soaked in water before they can be eaten. They have various uses, in particular they are used in Spain to make Horchata. They are sometimes known by their Spanish name, "chufa".

The tubers were originally cultivated by Ancient Egyptians in the Nile Valley; their cultivation was subsequently extended throughout other areas with temperate climate and fertile soil. Presently, they are mainly cultivated - at least for extended and common commercial purposes - in Spain, almost exclusively in the Valencia region. See the wikipedia article on Cyperus esculentus for nutritional information.