Cyperus (PROSEA)

Plant Resources of South-East Asia
Introduction

List of species

Cyperus L.

Protologue: Sp. pl. 1: 44 (1753); Gen. pl. ed. 5: 26 (1754).

Family: Cyperaceae

Chromosome number: x= 5, 8, 9, 11, 13, 19, 29;

C. brevifolius: n= 9, 2n= 32, 120,

C. iria: n= 36, 56, 64, 2n= 18,

C. kyllingia: n= 43, 62,

C. papyrus: n= c. 50, 2n= c. 102,

C. procerus: n= 52, 2n= 18, 64

C. rotundus: n= 40, 42, 48, 50, 54, 56, 64, 69, 76, 2n= 16, 26, 96, 108, 152

C. esculentus: 2n= 96, 108.

Major species

Cyperus bulbosus Vahl, Enum. 2: 342 (1806), synonym: C. jemenicus (non Rottb.) Clarke (1884).

Cyperus elatus L., Cent. pl. 2: 301 (1756), synonyms: C. racemosus Retz. (1789), C. scoparius Decne (1834), C. bispicatus Steud. (1855).

Cyperus esculentus L., Sp. pl.: 45 (1753).

Cyperus malaccensis Lamk, Tabl. encycl. 1(1): 146 (1791), synonyms: C. monophyllos Vahl (1806), C. spaniophyllus Steud.(1855), Chlorocyperus malaccensis (Lamk) Palla (1912).

Cyperus papyrus L., Sp. pl.: 47 (1753), synonyms: Papyrus antiquorum Willd. (1812), P. domesticus Poir. ex Cuvier (1825), Chlorocyperus papyrus (L.) Rikli (1895).

Cyperus procerus Rottb., Descr. icon. rar. pl.: 29, t. 5, f. 3 (1773), synonyms: C. ornatus R. Br. (1810), C. heynii Boeck. (1868).

Cyperus rotundus L., Sp. pl.: 45 (1753), synonym: Cyperus curvatus (non Vahl) Llanos (1851).

Cyperus kyllingia Endl.

Vernacular names

Nut sedge, nut grass, cyperus (En)
Indonesia: teki
Malaysia: teki
Thailand: ya kok, ya haeo, haeo
Vietnam: cói, lác.

C. bulbosus

Vietnam: cói củ.

C. elatus

Indonesia: wlingi (Javanese), lilisungan (Sundanese), tintilohuangga (northern Sulawesi)
Philippines: kobong-kobong (Bisaya)
Vietnam: cói mào.

C. esculentus

Chufa, yellow nut grass, tiger nut (En)
Amande de terre, souchet sucré (Fr)
Cambodia: më:m phlông
Thailand: haeo-thai (central)
Vietnam: cói bổ, củ gấu.

C. malaccensis

Chinese mat grass (En)
Indonesia: bundung (southern Kalimantan), darengdeng (Sundanese), pea-pea (Sulawesi)
Malaysia: selimbu, menderong darat (Peninsular)
Philippines: balangot (general), baga-as (Panay Bisaya), talaid (Bagobo)
Thailand: yaa saam liam (Bangkok)
Vietnam: cói, cây cói, lác.

C. papyrus

papyrus, paper reed, Egyptian paper plant (En)
Thailand: kok eeyip (Bangkok).

C. procerus

Indonesia: rumput adem (general)
Malaysia: rumput mensiang
Thailand: kok ta krap (Bangkok), yaa ta krap (central).

C. rotundus

Purple nut grass (En)
Souchet rond (Fr)
Indonesia: teki (Indonesian), mota (Madura), karelawai (Sumba)
Malaysia: rumput haliya hitam
Philippines: mutha (Tagalog), ahos-ahos (Bisaya), boto-botones (Bikol)
Burma (Myanmar): monhnyin-bin
Cambodia: krâva:nh chru:k
Laos: hèwz hmu:
Thailand: haeo-mu (general)
Vietnam: củ gấu, hương phụ.

Origin and geographic distribution

Cyperus comprises about 600 species distributed worldwide, with the vast majority occurring in the tropics and subtropics. Most of the about 80 species found in South-East Asia have a pantropical or palaeotropical distribution.

C. bulbosus occurs in tropical Africa, southern Asia and tropical Australia. In Malesia it is rare and only found in Indonesia on some small islands like Damar Besar, Madura and Timor.

C. elatus originated in Asia and is distributed from India to Indo-China, the Philippines and Indonesia. In South-East Asia it is common in Thailand, Cambodia, Vietnam, Peninsular Malaysia, Indonesia (Sumatra and Java), less common in the Lesser Sunda Islands, Borneo, Sulawesi and the Philippines, and absent in the Moluccas and New Guinea.

C. esculentus has a very wide distribution from the Mediterranean to southern Africa, from India throughout South-East Asia to Australia and it is abundant in America. In Malesia, it is rare and has only been collected on Java. It is also cultivated for its edible tubers (Mediterranean, Africa, Western Europe, United States) and in some regions it has become an aggressive weed, easily propagating by small tubers and often distributed unintentionally together with other crops. The cultivated form is thought to have originated in the Mediterranean.

C. malaccensis, originating in Asia, is distributed from Iraq through India to southern China, northern Australia and Polynesia and is common throughout South-East Asia. It is cultivated as a matting sedge in northern Sulawesi, the Sangir Islands, and in Brazil.

C. papyrus originated in Central Africa and has spread over tropical Africa between 13 °N and 26 °S (including Madagascar). It has been cultivated in Egypt and neighbouring areas since ancient times and is sometimes naturalized in the Mediterranean area (Israel, Sicily). Nowadays it is rarely cultivated as a fibre plant, but it is widely grown as an ornamental, for instance in Java.

The origin of C. procerus is unknown. It is distributed from India, Sri Lanka and Nepal through South-East Asia to eastern China, Taiwan and Australia (Queensland). In Malesia it occurs in Peninsular Malaysia, Java, Borneo, the lesser Sunda Islands and the Philippines (Luzon), but it is not common.

C. rotundus is thought to originate in Africa. Now it is widely distributed throughout the warmer parts of the world and it is very common all over South-East Asia.

Uses

In general, the genus Cyperus is economically unimportant and better known for its weeds than its useful plants. Some species are used for their edible tubers (especially in times of food scarcity), for their edible stems (as vegetable or as forage), for their dried stems (ropes, baskets and other wickerwork), or as ornamentals or for medicine. But several species are best known as weeds in agriculture.

Where C. bulbosus is common the young tubers are eaten. C. esculentus produces tubers that are eaten raw, cooked, or roasted and ground to a flour which is used in bread-making, in ice-cream, sherbets or drinks, or in the preparation of porridge mixed with a cereal. In Spain, a very popular drink called "horchata" is prepared from the tubers and is obtained by extracting a milky liquid from thoroughly ground tubers. Oil can be extracted from the tubers, formerly used to make soap. The dried stems are used to make mats and wickerwork. Tubers and aboveground parts also serve as a forage. The plant is also used as a stimulant and as a sedative in Asia and Africa.

The tubers of C. rotundus are also edible; it is not cultivated for this purpose like C. esculentus, but the tubers are collected from the wild in times of need.

Several of the weedy species, particularly C. rotundus, are used in local medicine. In South-East Asia, the most widespread medicinal applications of the tubers are against hepatic disorders, as an emmenagogue and for post-partum treatment, as a stomachic, as a febrifuge, against renal and urologic disorders, and to treat ulcers. It is interesting that Cyperus species are used in similar ways in other parts of the world, e.g. in South America. Other medicinal uses in South-East Asia are as a stimulant, diuretic, anthelmintic (in large doses), galactagogue, sudorific, as a mouthwash against diseases in the mouth and toothache, and as an astringent against diarrhoea and dysentery.

Usually the powdered tubers (often in decoctions) are used internally, but for ulcers, scorpion stings and snake bites a poultice is applied externally. Cyperus species are also well known in Chinese and Japanese traditional medicine and are reported to be used in India as stimulants, diuretics, anthelmintics and stomachics for example. In the Ayurvedic system of medicine the tubers are believed to be tonic, and to act as a nourisher and rejuvenator; they are part of several complex preparations.

Because of their aroma, the tubers are used to perfume clothing and to repel insects. The roasted tubers have also been used as a substitute for coffee and as an adulterant for cocoa.

The fatty oil extracted from the tubers was formerly used to make soap. The dried stems are used to make mats, ropes, baskets and other wickerwork. Tubers and aboveground parts can also serve as a forage. Some species are used for their edible tubers (especially in times of food scarcity), for their edible stems (as vegetable or as forage), and some are used as garden ornamentals.

The stems of C. elatus serve in Indonesia for weaving hats (Java) and mats (Sulawesi). The stems of C. malaccensis are often and widely used in South-East Asia for tying and for weaving mats, baskets and hats. In some towns on Luzon (the Philippines) slippers are made from them. In Central Java (Indonesia) the stems are plaited into ropes by fishermen to attract young fish, which are caught and placed in fishponds. In India C. malaccensis is used for weaving mats, hats and baskets; it is also woven into mats in China and Taiwan. The tough stems of C. procerus are split into three to serve as string or binder twine, e.g. in Java.

The pith of the stem of C. papyrus was used by early civilizations (Egyptians, Greeks, Romans) to make a primitive form of paper, and the plant was cultivated for this purpose in the Egyptian Nile delta, Palestine and southern Europe. It was already in use by 3500 BC and fragments of papyrus sheets dated at 4600 years old have been found. The fibrous outer parts of the stem were used in ancient Egypt for making ropes, baskets, nets, sails, mats, sandals and furniture coverings. The stems were also made into boats and dried plant material served as fuel. Nowadays it is only cultivated on a small scale and used locally for mat-making and similar purposes. It is considered a potential raw material for the production of paper and board, though pulping experiments carried out in the 1920s and 1950s gave unsatisfactory results. Around 1920, a papyrus-based pulping mill operated for a short time in South Africa.

The rhizomes of C. malaccensis are used medicinally in Vietnam for post-partum treatment and against oedemas; they are considered to be diuretic. The stems and rhizomes of C. papyrus are edible. C. elatus and C. papyrus are eaten by cattle. Experiments indicate that the high biomass production of C. papyrus makes it effective in removing N and P from wastewater and eutrophic pond water. Many Cyperus are considered weeds in rice fields, though they also provide green manure.

Production and international trade

Only tubers of C. esculentus are produced and traded commercially, but not in South-East Asia. All species are considered as weeds that are difficult to eradicate. In particular C. rotundus and the weedy forms of C. esculentus are considered as belonging to the world's worst weeds.

No production or trade statistics for fibre Cyperus are available. In the past (1200 AD), mats made from C. elatus were traded from Java to China. At the present time mats and other products from C. malaccensis are made in Vietnam for export, but quantities are unknown.

Properties

Tubers of C. esculentus are rich in starch (20-30% on dry weight basis) and oil (20-28%) and are a good source of P and Fe, with small quantities of protein. The oil consists primarily (80%) of unsaturated fatty acids, mainly oleic acid.

Per 100 g edible portion, tubers of C. rotundus contain approximately: water 59 g, protein 2.3 g, fat 1.6 g, carbohydrates 20 g, fibre 16 g, ash 0.8 g. The energy value averages 790 kJ per 100 g. The fresh tuber contains about 0.6% essential oil, mostly consisting of sesquiterpenoids (copadiene, epoxy-guiane, rotundone and cyperolone). The petroleum ether extract of the tubers exhibits anti-inflammatory activity against carrageen-induced oedema in albino rats and oestrogenic activity and some spasmolytic action on isolated uterus of guinea pig and rat.

The underground parts of several weedy species contain essential oils, about 0.5-1% in the case of the fresh tubers of C. rotundus, mainly consisting of terpenoids or sesquiterpenoids (e.g. cyperone, cyperol, cyperolone, cyperene, copadiene, epoxy-guiaene, rotundone, rotundol, patchoulenone (= cyperotundon), kobusone, sugeonolacetate, sugetriol, oxido-eudesmenol, mustakone and β-selinene).

When Tanzanian medicinal plants were screened, C. rotundus showed activity in a test for in vitro antimalarial activity. Further phytochemical investigations revealed the presence of several active compounds: α-cyperone, an auto-oxidation product of β-selinene, patchoulenone, caryophyllene epoxide, 4,7-dimethyl-1-tetralone (all sesquiterpenes) and 10,12-peroxycalamenene (a sesquiterpene endoperoxide). There is evidence that the peroxide moiety of the latter molecule is important in the activity against malarial parasites, as are artemisinin (from Artemisia annua L.) and ascaridole (from Chenopodium oil).

The essential oils furthermore have nematicidal and insecticidal activity (e.g. against bugs, beetles and caterpillars), and the insect- repellent activity is comparable to that of citronella oil. The aggressive spread as a weed may also be partly attributed to the sesquiterpenes present in the oil, which inhibit the growth of seedlings of agricultural crops.

Several investigations have focused on the anti-inflammatory and/or anti-pyretic effects of C. rotundus. Preliminary observations were made on the ethanolic extracts of the roots. The mechanism of activity was subsequently found to be inhibition of prostaglandin synthesis. In addition to the effects mentioned, some antihistaminic, smooth muscle relaxant, anti-emetic, antihepatotoxic and antifungal activities were observed. A carrageen-induced oedema test in rat revealed that the triterpenoid in the light petroleum ether extract of the root is the main active compound with in vivo anti-inflammatory activity.

Small amounts of saponins have been reported from C. rotundus, and the main substance of the lipid fraction in tubers of C. iria has been shown to be hentriacontanol. In Malaysia, a compound isolated from a steam distillate of the whole plants of C. iria appeared to be identical to juvenile hormone produced by insects. Nymphs of the acridid Melanoplus sanguinipes feeding on C. iria showed pronounced morphogenetic effects when they moulted to adults, so the compound can be considered as the plant's defence mechanism against insects. The water extract of rhizomes exhibits bradycardia and cardia depressant, coronary vasodilator, hypotensive and diuretic activities. Clinical trials with root extracts in 64 obese patients found hypotensive activity in those patients with hypertension, but no effect in normal patients.

C. malaccensis has been said to provide very good matting material, but mats made from it have also been described as less durable than those made from Fimbristylis umbellaris (Lamk) Vahl and as much more brittle than those of Lepironia articulata (Retz.) Domin. The character of weaving material from C. malaccensis largely depends on the preparation method. The 3-sided stems may be split and the sides pulled apart, or just one side may be removed. If only a little pulp is removed, the straw is thick and soft, but if much is removed and the straw is finely split, the straw is thin and fine.

Papyrus fibre cells are (1-)1.8(-4) mm long and (8-)12(-25) μm wide. They are narrow, thick-walled and have pointed ends. Investigations in the early 20th Century showed that papyrus stems from Egypt provided a moderate pulp yield of fair quality, but the pulp was difficult to bleach. Experiments with C. papyrus in South Africa gave pulp yields of 45-48%. Because the stems have no nodes, the pulp does not contain hard particles, and even rayon-grade pulp has been produced from papyrus. However, the pith must be removed; it does not add strength to the paper but uses pulping chemicals and makes washing and forming of the paper difficult. The pith is not a problem for the production of hardboard. More recently it has been found that the major pulping chemicals successfully pulp papyrus and the pulp can be bleached under conditions similar to those required for rice straw. The resulting pulp can be used as the main constituent of writing and printing papers, but not for wrapping paper.

Vietnamese C. malaccensis rhizomes were found to contain approximately 3.1% tannin, 0.7% flavonoids, 0.5% essential oil and 0.5% alkaloids. In a Kenyan study the crude protein content of papyrus umbels decreased from 11% (juvenile) to 4% (dead) and that of culms from 4% to 2%. The ruminal dry matter digestibility of the umbels decreased from 38% to 13% and that of the culms from 46% to 3%.

Adulterations and substitutes

The following species combine several of the major applications of Cyperus: Artemisia spp. (e.g. emmenagogue, stomachic, febrifuge, diuretic and ulcers), Desmodium spp. (e.g. hepatic disorders, stomachic, febrifuge, diuretic and ulcers), Hibiscus spp. (e.g. emmenagogue, stomachic, febrifuge, diuretic and ulcers), Elephantopus scaber L. (e.g. emmenagogue, febrifuge, diuretic and ulcers), Heliotropium indicum L. (e.g. emmenagogue, stomachic, diuretic and ulcers), Leonurus spp. (e.g. emmenagogue and for post-partum treatment, febrifuge and diuretic) and Tinospora spp. (e.g. hepatic disorders, stomachic, febrifuge and ulcers). However, the active compounds are in general quite distinct and the similar medicinal use is not a result of chemical conformity. Chemically related substances are found in some grass genera such as Cymbopogon; their essential oils have very similar sesquiterpenes and some similar applications.

Description

Perennial or annual herbs, tufted or with creeping rhizome or stolons, sometimes with tubers at intervals.
Stem (culm) usually erect, solid, triangular (sometimes terete) in cross-section, usually leafy only at the base.
Leaves tristichous, narrowly linear, grass-like, rarely lanceolate or elliptic, the lower ones often scale-like, covering the base of the stem and the rhizome, rarely all reduced to sheaths only.
Inflorescence terminal, often anthelate, simple to decompound, umbel-like or capitate; rays subtended by a leaf-like bract, the base enclosed in a tubular, two-keeled prophyll, the bracts usually approximate as though forming an involucre.
Spikelets more or less compressed, quadrangular to subterete, 1-many-flowered, axis (rachilla) often winged by the decurrent base of the glumes, persistent or caducous (in the latter case spikelet falling as a whole); glumes distichous, usually 2 basal ones empty.
Flowers bisexual, the uppermost often male or sterile; stamens 3, 2 or 1; style continuous with the ovary, 3- or 2-fid.
Fruit a nut, sessile or shortly stipitate, trigonous or lenticular.

C. bulbosus

Perennial with thread-like rhizomes which disappear after having formed tubers.
Tuber ovoid to fusiform, 1-1.5 cm long, bulb-like, whitish turning shiny black, coat coriaceous, striate, splitting into some caducous segments.
Stem arising from a tuber, slender, (5-)15-30 cm × 0.5-1 mm.
Leaves several, often recurved, as long as or longer than the stem, 1-2(-4) mm wide, scaberulous in upper part.
Inflorescence simple, often reduced to a spike; involucral bracts (1-)2-3, up to 10 cm long, distinctly separated from each other.
Spikelet 8-28-flowered, 1-3 cm × 2 mm; rachilla flexuous, broadly winged, persistent; glumes 9-11-veined; stamens 3, stigmas 3.
Fruit trigonous, obovoid to ellipsoidal, 1.5 mm × 0.5 mm, black.

C. elatus

A perennial herb with very short rhizome; stems tufted, tall, 0.5-1(-2) m × 3-10 mm, smooth.
Leaves flat or somewhat plicate with midrib prominent beneath and 2 lateral veins strongly marked above; lower sheaths black-purplish; blade 4-10(-15) mm wide, bright green above.
Inflorescence up to 30 cm in diameter, compound; involucral bracts 4-8, up to 75 cm long, overtopping the inflorescence; primary rays up to 10, unequal, up to 20 cm long; secondary rays 2-5 cm long; spikes digitately arranged, 2-7 cm × 3-5 mm.
Spikelets 6-16-flowered, 3-6 mm × 1 mm; glumes ovate, 1.2-1.8 mm × 1 mm, 3-5-veined, mucronulate; stamens 3; stigmas 3.
Nut trigonous-ellipsoid, up to 0.9 mm × 0.4 mm, yellow-grey-brown.

C. esculentus

Perennial with very slender, yellowish rhizomes clothed with pale scales; rhizomes often disappearing after having formed tubers.
Tuber ovoid to globose, about 1 cm in diameter, transversely zoned when young, grey tomentose when ripe.
Stem slender, rigid, 10-50 cm × 1-2 mm.
Leaves several, somewhat shorter or longer than the stem, 3-6 mm wide.
Inflorescence simple or compound, loose to dense, umbel-like; involucral bracts 3-6, the lower 1-2 usually much overtopping the inflorescence; primary rays 3-8, unequal, 3-10(-15) cm long; spikes ovoid, with few to numerous spikelets.
Spikelet 8-16-flowered, 5-18 mm × 2 mm; rachilla slightly flexuous, broadly winged; glumes distinctly 7-veined over their whole breadth, golden-yellow to pale brown; stamens 3, stigmas 3.
Fruit trigonous, obovoid, 1.5 mm × 1 mm.

C. malaccensis

A perennial herb with stout stolons and woody rhizome; stems approximate, robust, 60-175 cm × 12-15 mm, spongious, triangular with concave sides, smooth.
Lower leaves reduced to spongious sheaths up to 20 cm long, upper ones much shorter than the stem but with small blade 5-10(-18) mm wide and abruptly acuminate.
Inflorescence broader than long, about 15 cm in diameter; involucral bracts 3-4, flat, erect to reflexed, up to 30 cm × 8-15 mm, overtopping the inflorescence; primary rays 3-6(-10), spreading, unequal, 3-10 cm long; secondary rays slender, about 2 cm long; spikes broadly ovoid in outline with 6-12, spicately arranged spikelets.
Spikelet subcylindrical, 1-3 cm × 1.2-1.7 cm, with 16-20(-40) flowers; glumes chartaceous, ovate to elliptic, up to 2.2 mm × 1.5 mm, indistinctly 5-7-veined; stamens 3; stigmas 3.
Nut trigonous-cylindrical, about 2 mm × 0.5 mm, brown-black.

C. papyrus

A perennial herb with coarse, short rhizome; stems up to 5 m tall, trigonous, pithy, clothed at base with brown bladeless sheaths.
Leaves only with small blade up to 1 cm wide in sterile shoots.
Inflorescence umbelliform, 20-35 cm in diameter; involucral bracts up to 12, lanceolate, much shorter than the inflorescence; primary rays numerous, slender, suberect, subequal, 10-30 cm long; secondary rays up to 5 cm long; spikes 1-3 cm × 6-10 mm, bearing distichously many spikelets.
Spikelet cylindrical, 6-12 mm × 1 mm, 5-17-flowered; glumes ovate-elliptic, 2 mm long, 3-veined green keel, light brown; stamens 3; stigmas 3.
Nut trigonous-cylindrical, about 1 mm long.

C. procerus

A perennial herb with stoloniferous rhizome; stems stout, 70-125(-175) cm × 0.5-1 cm, smooth, at base clothed with brown to purplish sheaths.
Leaves firm, spongious or coriaceous, oblong-canaliculate, 9-15 mm wide, gradually acuminate at apex.
Inflorescence subcompound, loose, 10-15 cm long; involucral bracts 3-4, erect to spreading, up to 70 cm long, the larger ones far overtopping the inflorescence; primary rays 3-7, unequal, 6-20 cm long, spreading; secondary rays absent to very short; spikes broadly ovoid, 2-4 cm long and wide, loose.
Spikelets up to 10-18 in the terminal spike, 3-4 in the lateral ones, spicately arranged, lower ones at right angles to the rachis, 10-35 mm × 2-3 mm, up to 40-flowered; glumes ovate to elliptic, 2.5-3 mm × 2 mm, hardly keeled, 7-veined, red-brown; stamens 3; stigmas 3.
Nut obovoid to ellipsoid, triangular, 1.5 mm × 0.8 mm, black-brown.

C. rotundus

Perennial with long, slender, stout, wiry, dark brown rhizomes giving rise to tubers at intervals of 5-25 cm, forming tuber chains that extend to a considerable depth in the soil.
Tuber subglobose or ellipsoid, 0.5-2.5 cm long, white and succulent when young, turning fibrous brown-blackish, without grey tomentum, not zoned.
Stem slender, 15-30(-75) cm × 1-2 mm.
Leaves several, linear, flat, 10-30 cm × 2-6 mm, scabrid on the margins in the upper part.
Inflorescence composed of spikes, arranged as a simple or compound umbel, up to 15 cm × 10 cm, usually much smaller; involucral bracts 2-4(-6), up to 30 cm long, as long as or overtopping the inflorescence; primary rays 3-9, very unequal, up to 10 cm long; spikes ovoid, loose to dense.
Spikelets 10-40(-100)-flowered, 1-3.5 cm × 2 mm; rachilla flexuous, broadly winged; glumes 5-7-veined over one third or one half of either side of the midvein, deep brown; stamens 3, stigmas 3.
Fruit trigonous, oblong-obovoid, 1.5 mm × 0.50-0.75 mm, brown to black, rarely maturing.

Growth and development

Most C. rotundus plants originate from a tuber; seed production is possible but unimportant. The sprouting tuber produces a rhizome which terminates as a green aerial shoot. While emerging from the soil a swelling appears on the rhizome, often near the surface, but up to 20 cm depth, usually called a "basal bulb". On the basal bulb roots are formed and rhizomes grow out from it for a distance of 1-30 cm horizontally before the tip turns up to produce a new aerial shoot with another basal bulb, or, alternatively, to form a subterranean tuber from which another rhizome appears at the apical end, thus forming chains of tubers. The basal bulb and aerial shoot population may increase fivefold in the first 4 weeks after a tuber has been planted. It is believed that there are no buds at the nodes of the rhizomes and that no new plants can grow from rhizome fragments. Rhizomes and tubers are white and fleshy when young and some become firmly packed with starch. On aging they darken, harden, and most of the tissue exterior to the endodermis of the rhizomes sloughs off to give a wiry structure resistant to desiccation and decay. Most tubers are found in the top 15 cm of the soil, and when planted at 90 cm depth are unable to grow to the surface. In cropped areas the starch reserves are greatest in tubers that are below the disturbed layer; in uncropped land they are greatest in tubers near the soil surface.

Short photoperiods stimulate flowering, and the period from emergence to flowering varies between 3-8 weeks. Short photoperiods might also stimulate tuber formation and it is believed that tubers do not form until flowering begins. Flowers are cross-pollinated, mostly by wind. Although many seeds are formed, they are rarely rare. Seed germination averages 1-5%. Most tubers are found in the top 15 cm of the soil, and when planted at 90 cm depth, they are unable to grow to the surface. In cultivated areas starch reserves are highest in tubers that are below the disturbed layer, in non-cultivated land in tubers near the soil surface.

The development of C. esculentus is practically the same. Flowering, however, is stimulated by photoperiods of 12-14 hours and the viability of the seed produced is much higher than in C. rotundus, e.g. above 50%. In the weedy forms seed propagation is much more important.

C. iria spreads by seed that may germinate immediately as soon as it falls on the ground. Germination percentage is about 40% but is much lower if the soil is under water.

In Java C. elatus, C. malaccensis and C. papyrus flower year-round. Natural propagation of C. elatus is by the nuts, which are dispersed by water and birds. The nuts of C. malaccensis and C. procerus are dispersed. Some Cyperus species are known to have C₄-photosynthesis, whereas others have C₃-photosynthesis. C. papyrus has C₄-photosynthesis, which contributes to its exceptionally high productivity. The culms have numerous large intercellulair air cavities and "Krantz" chlorenchyma, which are involved in CO₂-recycling. Under natural conditions average annual growth rates up to about 40 g/m² dry weight per day have been recorded, and in hydroponic culture short-term growth rates up to 125 g/m² dry weight per day are possible. In Lake Naivasha, Kenya, the total standing biomass was found to be 7.8 kg/m² dry weight. Of this total biomass 57% was located in the rhizome, 29% in the culms, 13% in the umbels, and 1% in the roots. The majority of C. papyrus umbels do not produce flowers, but the umbels are the principal photosynthetic tissue in mature plants. In a closed canopy the leaves senesce during early extension of the culms, but the leaves can be important for photosynthesis in plants that develop from seed or during regrowth after cutting or burning.

Other botanical information

Cyperus is classified in the subfamily Cyperoideae and the tribe Cypereae. It seems to be most closely related to Bulbostylis and Fimbristylis. Cyperus is subdivided into 3 subgenera and numerous sections. Subgenus Cyperus includes most species in the Malesian Archipelago (about 60) and is characterized by a trigonous or, when lenticular, dorsoventrally compressed nut, often 3 stigmas, and by the Kranz syndrome. Subgenus Pycreus includes 9 species in Malesia and has a laterally compressed nut, persistent rachilla and 2 stigmas. Subgenus Kyllinga, which has often been treated as a separate genus, includes 7 species in Malesia (e.g. C. brevifolius and C. kyllingia) and is characterized by its laterally compressed nut, disarticulating rachilla and 2 stigmas.

Some differences exist between the wild weedy forms of C. esculentus and the cultivated ones. Cultivated chufa has grey-orange tubers (weedy chufa grey-brown), which are less fibrous and borne on short rhizomes (longer in the weedy forms); shoots arising directly from the tubers are ascending and rarely flower (in weedy chufa they are erect and flower easily), and are sensitive to frost (weedy chufa is frost resistant to a certain degree). It has been correctly proposed to classify the cultivated forms into the cultivar group Chufa.

In C. rotundus 2 subspecies are distinguished: subsp. rotundus and subsp. retzii (Nees) Kük. Subsp. retzii (synonym: C. retzii Nees) differs from subsp. rotundus by its stouter habit (stem 50-75 cm tall), the somewhat broader spikelets (about 2.5 mm wide when ripe) and the paler elliptical-oblong glumes (3.5-4 mm long). It appears in moist locations, sometimes as a weed, but never as a pest; it is often confused with Cyperus esculentus, which has glumes with 7-9 prominent veins and ovoid tubers with a grey tomentum. C. rotundus can be recognized by its usually dark brown rhizomes, which may produce several tubers in a chain. C. esculentus has yellowish rhizomes which end in a single tuber.

Another tuber-bearing species, C. stoloniferus Retzius, is also widespread in South-East Asia, growing on coastal sands. It acts as a sandbinder and might, although not reported, provide food in times of food scarcity.

In C. procerus the rachis of the spikes is normally smooth, but in all Malesian specimens it is more or less scabrous hispid. The Malesian plants may therefore be referred to var. lasiorrhachis Clarke. In C. malaccensis 2 subspecies have been distinguished:

subsp. malaccensis: found from the Mediterranean to South-East Asia; lower leaf sheaths surpassing the inflorescence rays; uppermost leaf with an elongated blade; spikelets densely flowered with glumes not conspicuously incurved.

subsp. monophyllus (Vahl) T. Koyama: occurring in China and the southern Ryukyu Islands; characteristics opposite to those mentioned above for subsp. malaccensis.

For several Cyperus species occurring in South-East Asia no reports exist on their use as a fibre plant in the Malesian region, whereas they are known to be used for weaving elsewhere. They include: C. alopecuroides Rottb., used for mat-making in Egypt since ancient times; C. cephalotes Vahl, made into mats in Japan; C. compactus Retz. (synonyms: C. dilutus Vahl, Mariscus microcephalus Presl), made into low-quality mats in Vietnam (Tonkin) and sometimes used for making roofs in Thailand; and C. exaltatus Retz., used as a fibre plant and for making fine mats in Korea since ancient times. C. corymbosus Rottb. (synonym C. tegetiformis Roxb.), probably does not occur in Malesia, but it yields material for matting and strings in, for instance, Thailand, Indo-China, India and China.

Ecology

Most Cyperus species are hygrophilous and grow in moist or wet localities at low and medium altitudes, only a few occurring above 2000 m altitude in the tropics. Several species occur commonly in grasslands, on roadsides, river banks and waste places. Some species are noxious weeds in cropped land, and other species are colonizers of muddy and sandy flats near river mouths and along the coast.

C. bulbosus grows on dry sandy soils, in Malesia only near the sea.

C. esculentus grows in seasonally wet grassland, in irrigated crops, in damp grassland and along watercourses. It is also quite drought resistant but does not tolerate shade. Optimum average temperatures are 27-30 °C, and optimum rainfall varies between 600-1200 mm. Preferred soils are light sandy loams with pH 5.5-6.5, but it grows on any kind of soil provided it is well drained. It is also quite tolerant of saline soils. Short photoperiods of 8-12 hours favour tuber formation, long photoperiods favour other vegetative growth.

C. papyrus is the dominant species in most African permanent swamps. It is adversely affected by seasonal flooding regimes exceeding 3-4 m in amplitude, flash flooding or very low water levels during the dry season. Papyrus is sometimes considered a nuisance, forming floating islands that obstruct navigation and water flow.

C. procerus, and especially C. malaccensis, prefer muddy habitats within the influence of salt or brackish water. C. elatus grows on riverbanks, in swamps, rice fields and meadows, and other open wet locations up to 700(-1000) m altitude. C. malaccensis is found, often abundantly, in moist habitats, usually within the influence of salt or brackish water (muddy estuaries, mud flats and sandy foreshores covered by spring tides) and often forming a dense fringe vegetation. C. procerus grows in open, wet locations, like swamps and pools, often near the sea in brackish localities, and in wet rice fields, usually up to 50 m altitude, but also near Bogor (West Java) at 250 m altitude. In Indonesia C. elatus, C. malaccensis and C. procerus are considered weeds of minor importance in rice fields. They can be controlled by manual weeding.

C. rotundus is found in cultivated fields, on roadsides, in neglected areas, at the edges of woods, along irrigation canals and streams, all over the world in both hemispheres up to about 50° latitude where cold limits its further expansion. It grows without problems at any elevation, humidity, in almost any soil type, soil moisture and pH, and can survive very high temperatures. Only low temperatures, shade, and soils with high salt content can limit its growth, and the tubers can remain dormant for a long time to carry the plant through the most extreme conditions of heat, drought, flooding or lack of aeration.

Propagation and planting

All Cyperus species can be propagated by seed, and tuber-forming species can be easily propagated by tubers.

C. esculentus cv. group Chufa is propagated by tubers which are first soaked in water for 2-3 days before being planted. Freshly harvested tubers may show a dormancy period, which can be broken by a cold treatment (e.g. in temperate climates by overwintering). Planting distance varies, usually in rows 60-90 cm apart, at 10-15 cm intervals, 2.5-4 cm deep, at wider spacings usually with 2 tubers per hole. A spacing of 15 cm in 75-90 cm distant rows requires 35-45 kg tubers per ha as planting material. Farmyard manure and NPK (6:6:8, up to 1000 kg/ha) is recommended in Spain.

The seed of C. papyrus needs light to germinate.

Husbandry

Some Cyperus species, especially C. rotundus are serious weeds of rice, sugar cane, maize and vegetables in South-East Asia. Digging up all rhizome parts and/or the planting of crops that produce continuous shade for several years can eradicate them. Biological control methods have not yet been successful, but promising results have been obtained with the rust Puccinia canaliculata for the weedy forms of C. esculentus.

Diseases and pests

No serious diseases and pests are known. In the United States negrobug (Corimelaena pilicaria) punctures the tubers; sometimes harm is done by root-knot nematodes (Meloidogyne spp.). The tubers reach maturity in 3-4 months; they are harvested manually or mechanically at the end of the dry season when the plants begin to wither. Average yields of tubers on sandy soils range from 800-900 kg/ha; under optimum conditions 8-14 t/ha can be obtained. Harvested tubers are cleaned, washed, and dried before being graded and stored in thin layers under shelter.

C. rotundus has been reported as a host plant for Rhizoctonia disease and for root-knot nematodes (Meloidogyne spp.).

In Peninsular Malaysia, Cyperus is susceptible to attack by smut fungi (Ustilago spp.). In southern China (Guangxi) C. malaccensis blight, caused by Phytophthora cyperi, occurs widely.

The stem borer Schoenobius ochraceellus has been recorded on C. elatus and C. procerus in Indonesia, mostly in the subterranean stem parts.

Yield

C. rotundus may produce up to 40 t subterraneous plant material per ha per year. It is a serious weed of rice, sugar cane, maize and vegetables in South-East Asia.

No information is available on fibre Cyperus yields in South-East Asia. The annual aboveground production of C. papyrus in Lake Naivasha swamp in Kenya has been estimated at about 50 t/ha dry matter per year.

Handling after harvest

The tubers of C. rotundus are briefly scorched by fire to get rid of the fine roots. They are then washed and dried in the sun or by hot air.

In processing C. malaccensis stems in Indonesia, one of the ribs is removed and the remaining stem is dried in the sun for 3 days. Then the stems are spread out indoors for 24 hours to become supple, after which they are smoothed with a piece of bamboo. In the Philippines whole stems are plaited into coarse matting, whereas fine matting is made by splitting the stems before drying. Splitting preferably is done when the stems are fresh and in any case before they are dry. The strips may be placed in the sun for a first quick drying. After this, the straw finishes drying in the shade. The resulting unbleached, light green-coloured straw is ready for use, but it may also be whitened and toughened by keeping it damp in the sun for several days. If it dries completely in the sun, it becomes brittle. For mat-making in Gorontalo (Sulawesi) C. elatus stems are split into three and the strips are smoothed with a piece of wood. In Vietnam the stems are split and dried in the sun.

In ancient Egypt C. papyrus was probably made into writing material by stripping the fibrous outer parts from the stems and slitting the inner pith into strips. These strips were laid side by side, with a second layer of strips placed crosswise on top, dampened, pressed, dried in the sun, and polished.

Genetic resources and breeding

No germplasm collections and breeding programmes of Cyperus are known to exist.

Prospects

It is expected that in South-East Asia Cyperus will primarily remain a weed problem for which effective herbicides and biological control methods still have to be found. It is not recommended to plant weedy species for medicinal purposes. Comparatively little research has been done on the chemistry and pharmacology. More research seems worthwhile on those Cyperus species used for similar medicinal purposes in many areas of the world.

Based on their traditional use by local people, C. elatus, C. malaccensis and C. procerus will remain of local importance as sources of weaving and binding material in South-East Asia. C. papyrus has a high productivity and may have some potential as a raw material for papermaking.

Compared to the efforts to eradicate Cyperus weeds in cultivated land, the cultivation of C. esculentus cv. group Chufa is of no importance.

Literature

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Selection of species

Authors

P.C.M. Jansen & N.O. Aguilar
Nguyen Khac Khoi
U.A. Dasuki