Common Name: Chinese Keys

General Information

Boesenbergia rotunda is a herbaceous, perennial, almost stemless plant growing from 30 - 80cm tall[]. The leafy shoots, which bear 3 - 7 erect leaves, grow from a strongly aromatic, bright yellow rhizome[, ].
The plant has a long history of use as a spice and medicinal plant, especially in southeast Asia, where it is often cultivated in small scale, subsistence farming systems, and is commonly found for sale in local markets[, , ].

Known Hazards

None known

Botanical References

,

Range

E. Asia - China, India, Sri Lanka, Malaysia and Indonesia.

Habitat

Dense forests at elevations around 1,000 metres in southern China[]. Mixed deciduous and evergreen forests, on limestone hills along streams, from sea-level up to elevations of 1,200 metres[].

Properties

Edibility Rating
Medicinal Rating
Habit	Perennial
Height	0.30 m
Cultivation Status	Cultivated, Wild

Cultivation Details

A plant of the hot, humid, tropical and subtropical lowlands, where it is found at elevations up to 1,000 metres. It grows best in areas where annual daytime temperatures are within the range 18 0 30°c, but can tolerate 12 - 35°c[]. Mature plants can be killed by temperatures of -12°c or lower, although new growth can be severely damaged at temperatures of -1°c[]. It prefers a mean annual rainfall in the range 1,200 - 3,000mm, but tolerates 1,000 - 5,000mm[].
An easily grown plant, it succeeds in full sun or light shade in a moist soil[]. Prefers a well-drained loam rich in organic matter[]. Succeeds in almost all types of soil but grows best in sandy soils[]. Prefers a pH in the range 6 - 7, tolerating 5.5 - 7.5[].
During its growth, the mother tuber emits long, straight, swollen carrot-like roots resembling Chinese keys[].
Plants grown in shady locations lose their cineole content much faster than those grown in sunny places[].
When grown for the rhizome and roots as a spice, the life cycle of a plant is about 5 months[]. Plants can produce young shoots for vegetable use and rhizome and roots for medicinal use for several years[]. If left undisturbed a plant can spread by its roots and may develop into a gregarious community[].
Young shoots to be used as a vegetable can be harvested as soon as 1 - 2 months after planting[]. The whole plants can be pulled up 4 - 5 months after planting for use as cooking spice and traditional medicine[]. If not harvested within 5 months after planting, the rhizomes will become woody and their quality as a spice will decrease[].
Specific parts of the plant, e.g. The enlarged roots for external use as medicine, can be selectively harvested later than 6 months after planting, without disturbing the growth of the plant[].
The average yield of fresh rhizomes and roots is about 10 - 30 t/ha at 4 - 6 months after planting[]. Being mainly a crop of smallholders for domestic use only, yield data are scarce[].

Edible Uses

The bright yellow, aromatic, strong, spicy, swollen rhizomes, especially when young, can be eaten raw, usually as a side dish with rice[, ]. They are also cooked in soups, stews and sambals, as well as being made into pickles[]. The rhizome is used as a flavouring in salads and cooked dishes[].
The roots can be collected by digging with a hoe at least 8 months after planting when the lower leaves turn yellow[].

The hearts of the stems can be eaten raw as a side dish with rice[].

Young leaves and shoots, usually along with the rhizome, are cut finely, mixed with coconut and spices, then wrapped in a banana leaf and steamed[]. The young spicy shoots are also used as a substitute for the rhizomes[].

Medicinal

The rhizome and roots are carminative, stomachic and tonic[]. They have a wide range of applications in traditional medicine where they are used as an ingredient in post-partum tonic mixtures; to treat digestive disorders such as colic, sprue, indigestion and wind; and as a remedy for coughs[].
Externally, the roots and rhizome are used as a treatment for ringworm, rheumatic and post-partum muscular pain, swollen abdomen and difficult urination in children[].

The roots and rhizomes contain a range of medically active substances, including monoterpenoids (geranial and neral), flavones and flavanones (pinostrobin, alpinetin and pinocembrin) and chalcone (cardamonin)[]. Three unusual dihydrochalcone derivatives (e.g. boesenbergin A) and three compounds related to panduratin A have also been isolated[].
Cardamonin is reported to be an effective anti-tumour agent[].
The essential-oil content of the rhizome and roots ranges from 1 - 3% of dry weight, 0.2 - 0.5% of fresh weight[]. The essential oil contains the following main compounds: 1,8-cineole (18 - 41%), camphor (13%), d-borneol (9.2%), d-pinene (4.1%), zingiberene (2.7%), curcumin (0.9%) and zedoarine (0.7%)[].
The essential oil from the rhizomes of Chinese keys (containing methyl cinnamate and zingiberone) has the ability to solubilize calcium kidney stones in vitro[].

Other Uses

None known

Propagation

Seed - needs to be sown as soon as it is ripe in containers at a temperature of 20c[].
Division.
A rhizome cutting planted in the open produces 4 - 5 leaves in about 1 month after planting; under shade, only 2 leaves are produced[].

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