Yellow Nutsedge
Binomial:	Cyperus esculentis
Type:	Perennial
Conditions:	Sun to light shade, thrives in moist conditions
Seed Dispersal:	Burrs
Seed Banking:	"Nuts" (tuber-like root nodules) can survive for decades
Vegetative Spread:	Via stolon

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.

Ecology

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.

Control

Crown and roots

• Mowing: Mowing does not control this plant at all, and in fact it thrives in lawns.
• Cultivation: Cultivation is effective if repeated regularly, but occaisional cultivation will simply serve to spread the plant around by distributing the tubers. Removal and replacement of the soil can be effective if done to a sufficient depth, and care is taken not to allow the new soil to be contaminated by any tubers.

The spread of the plant can be slowed by ensuring good drainage, as it thrives best in wet soils.

• Pulling: Pulling is difficult, as the roots easily break away from the tubers, allowing the plant to regrow using starches stored in the tuber. The surface growth is also known to break off from the root system when pulled, thereby leaving the roots in the ground. Frequent and consistent pulling will exhaust the plant over time.
• Flame: Ineffective.
• Barriers: Smothering is effective so long as the barrier is heavy, as this plant can push up against imperfect barriers when sprouting.
• Solarization: Not effective
• Pre-emergents (organic): Corn Gluten Meal in autumn, though simply preventing the introduction of seeds is a better method. Seeds are often spread via lawn mowing equipment.
• Pre-emergents (synthetic): Pre-emergents are effective in autumn.
• Systemic herbicides (synthetic): Contact herbicides are only somewhat effective. Root systems are not killed by glyphosate, though the tops may be burned if the herbicide is able to stick to the waxy leaves. Repeated applications of glyphosate (or simple cultivation) will eventually drain the starch reserves, but persistence is key.
• Grazing: High in silicates, so most grazing animals avoid this plant.
• Disposal: Below-ground parts and seeds should never be composted in low-temperature systems.
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