Curcuma Roxburgh (PROSEA)
- Protologue: Asiat. Res. 11: 329 (1810).
- Family: Zingiberaceae
- Chromosome number: x= 16, 21; 2n= 42 (C. angustifolia,C. aromatica)
Major species and synonyms
- Curcuma angustifolia Roxburgh, Asiat. Res. 11: 338 (1810).
- Curcuma aromatica Salisb., Parad. Lond. t. 96 (1805-1806), synonym: C. zedoaria Roxburgh (1810).
- Curcuma pierreana Gagnepain, Bull. Soc. Bot. Fr. 54: 405 (1907).
- Curcuma xanthorrhiza Roxburgh - see separate article.
- Curcuma zedoaria (Christmann) Roscoe - see separate article.
- Curcuma (En, Fr)
- Indonesia: temu
- Laos: kachièw, khminz
- Vietnam: nghệ.
C. angustifolia :
- Indian arrowroot, tikur (En)
- Cambodia: chahuöy, krâchâ:k
- Laos: kachièw dè:ng
- Vietnam: nghệlá hẹp.
C. aromatica :
- Wild turmeric, yellow zedoary (En). Safran des Indes (Fr)
- Laos: khminz khaix, khminz kh'am
- Thailand: wan-nangkham (central)
- Vietnam: nghệtrắng, nghệrừng.
C. pierreana :
- Vietnam: nghệpierre.
Origin and geographic distribution
Curcuma is mainly found in the Indo-Malesian region, from India throughout South-East Asia to the southern Pacific, and comprises 40-50 species. Several species have been introduced elsewhere in the tropics and there are numerous cultivars.
- C. angustifolia occurs wild and cultivated in the tropical and subtropical Himalaya areas of India, Pakistan, and northern Burma (Myanmar), and also in Laos.
- C. aromatica occurs wild and cultivated in India, Sri Lanka and the eastern foothills of the Himalayas. Occasionally, it is cultivated elsewhere (Indo-China, Japan).
- C. pierreana occurs wild in Vietnam where it is also cultivated.
The rhizomes and tuberous roots of Curcuma species contain starch, which is extracted from certain (perhaps all) species in times of food scarcity. The rhizomes of some species contain pigments which are used as a dye and others have aromatic oils which make them useful as a spice and medicinally. The young shoot and rhizome parts and inflorescences of some species are used as a vegetable. Most species also have ornamental value.
The starch present in the tuberous roots of C. angustifolia is considered as good as the starch of the true arrowroot ( Maranta arundinacea L.) and is used similarly. The starch is easily digestible and very suitable as a food for infants and people with digestive problems. In traditional medicine in India the rhizomes are used to cure bronchitis, asthma, fever, jaundice, leucoderma, and kidney and bladder stones. Sometimes the inflorescence is eaten as a vegetable.
C. aromatica is used as a source of starch, as a dye, cosmetic and drug. The inflorescences are very fragrant and plants in flower are esteemed as ornamentals. The rhizomes are highly aromatic (fresh and dried) and are widely used medicinally against rheumatism.
C. pierreana is used as a source of starch as a substitute for arrowroot.
Production and international trade
Most Curcuma species are only produced and traded locally. Some are rather important locally, but no statistics are available. Internationally, turmeric ( Curcuma longa L., synonym C. domestica Valeton) is the only extremely important Curcuma representative; it is used primarily as a condiment and spice (in curry powder).
Most Curcuma species contain starch, dyes and essential oils in their rhizomes and tuberous roots. Fresh rhizomes may contain 10-12% starch and 1-2% essential oils. No specific data are available for the species described here.
Rhizomatous, perennial, erect herbs, usually strongly tillering, up to 2 m tall. The base of each aerial stem consists of an erect ovoid primary tuber ringed with the bases of old scale leaves, bearing when mature several to many horizontal or curved rhizomes, which may again be branched. Roots fleshy, many of them bearing ellipsoidal tubers at their tips. Leafy shoots bearing a group of leaves surrounded by bladeless sheaths forming a pseudostem. Inflorescence spike-like, terminal on a leafy shoot or on a separate shoot from the base of the leafy shoot; peduncle (scape) covered by rather large bladeless sheaths; spike covered with bracts that are joined to each other for about half their length, forming pouches, the free ends usually spreading, each bract subtending a cincinnus of 2-7 flowers; uppermost bracts often larger, differently coloured and sterile (forming a coma); bracteoles thin, open to the base; calyx tubular, split unilaterally, unequally toothed; corolla with a more or less funnel-shaped tube and a 3-lobed limb, the dorsal lobe hooded and ending in a hollow hairy point; staminodes 3, petaloid, the 2 lateral ones folded under the dorsal corolla lobe, the anterior one, called labellum, is the most conspicuous part of the flower, and has a thickened central portion and thinner side-lobes which overlap the lateral staminodes; single fertile stamen, with a short broad filament and a versatile anther which is usually spurred at the base; ovary trilocular with 2 erect glands (stylodes) on top, style linear and held between the anther thecae, stigma expanded. Fruit an ellipsoidal capsule. Seed ellipsoidal, with a lacerate aril of few segments.
- C. angustifolia : up to 0.5 m tall; rhizome small, globose, with many oblongoid, pale tubers at the end of the roots; leaves lanceolate, 15-30 cm × 5-7 cm, petiole about 15 cm; inflorescence separate, appearing before the leaves, peduncle 7-15 cm long, spike 7-15 cm × 5 cm with flowers longer than the bracts, bracts green, coma bracts pink, corolla lobes pale yellow, staminodes bright yellow, labellum elliptical, 11 mm × 7 mm.
- C. aromatica : up to over 1 m tall; rhizome large, tuberous, cylindrical, 2.5 cm in diameter, root tubers mostly sessile, not at the end of the roots, rhizome and root tubers yellow inside and outside; leaves broadly lanceolate, 40-70 cm × 10-14 cm, pubescent below, petiole up to 70 cm long; inflorescence separate, usually appearing before the leaves, peduncle 5-8 cm long, spike 15-30 cm × 9 cm with flowers shorter than the bracts, bracts pale green, coma bracts pinkish, corolla lobes pinkish-white, staminodes deep yellow, labellum orbicular.
- C. pierreana : up to 20 cm tall; rhizome horizontal, cylindrical, 2 cm in diameter, whitish; leaves lanceolate-ovate, 15-20 cm × 6-8 cm, glabrous, petiole 9-11 cm long; inflorescence separate, appearing after the leaves, sessile, ovoid, 8 cm × 4-5 cm, with flowers longer than the bracts, bracts reddish with pinkish dots, coma bracts absent, corolla lobes white, lateral staminodes white at base, red at top, labellum suborbicular, 11-13 mm in diameter, white with a yellow central stripe.
The taxonomy of Curcuma is confusing and needs to be thoroughly revised. All species with tuberous rhizomes are probably used as a source of food in times of scarcity. There are also reports of the following species being used: C. leucorrhiza Roxburgh (India, very similar to C. zedoaria and C. aromatica ), C. montana Roxburgh (India, related to C. longa ) and C. rubescens Roxburgh (India, related to C. zedoaria ).
The ecology of Curcuma is not well known. Most species originated or grow in deciduous monsoon forest regions of South and South-East Asia, usually with an annual rainfall of 1000-2000 mm, up to 2000 m altitude in the Himalayan foothills. Curcuma grows best on loamy or alluvial, loose, fertile, friable soils and cannot stand waterlogging. In the wild the plants are found in shady sites.
Curcuma species can be propagated from rhizome parts. If primary rhizome tubers are planted, harvesting can take place after about 10 months, if other parts are used, 2 years are needed.
Clean weeding is recommended. When the leaves start to wither, the rhizomes may be dug up and harvested. Starch can be extracted by macerating the tuberous rhizomes in water and allowing the starch to settle. After several washings with water the starch is dried and is then ready for consumption. In villages, instead of extracting the starch immediately, the rhizome parts are often peeled, sliced and dried and are used when needed or offered for sale in local markets. In general, no specific agronomical practices are known for most species.
Genetic resources and breeding
Apart from the Curcuma collections present in botanical gardens, no special germplasm collections are known. Breeding programmes are only known for turmeric.
Curcuma deserves much more scientific attention, because of its interesting food, dye, spice, ornamental and medicinal aspects. Germplasm collection is urgently needed, simultaneously with a thorough taxonomic revision. Agronomically, it should be investigated whether large-scale production of promising species is profitable in the humid tropical lowlands of South-East Asia.
- Baker, J.G., 1890. Scitamineae. Curcuma. In: Hooker, J.D. (Editor): The flora of British India. Vol. 6. Reeve, London, United Kingdom. pp. 209-216.
- Burtt, B.L. & Smith, R.M., 1983. Zingiberaceae. Curcuma. In: Dassanayake, M.D. & Fosberg, F.R. (Editors): A revised handbook to the flora of Ceylon. Vol. 4. Amarind Publishing Company, New Delhi, India. pp. 499-505.
- Gagnepain, F., 1908. Zingiberaceae. Curcuma. In: Gagnepain, F. (Editor): Flore générale de l'Indo-Chine [General flora of Indo-China]. Vol. 6. Masson, Paris, France. pp. 57-70.
- Purseglove, J.W., 1972. Tropical crops. Monocotyledons 2. Longman, London, United Kingdom. pp. 521-528.
- Roxburgh, W., 1874. Flora Indica. Reprint Carey's Edition of 1832. Thacker, Spink and Co., Calcutta, India. pp. 7-13.
Halijah Ibrahim & P.C.M. Jansen