Cymbopogon martini (Roxb.) J.F. Watson
Family
Gramineae
Synonyms
Andropogon martini Roxb., Cymbopogon martini (Roxb.) J.F. Watson var. motia auct., p.p., Cymbopogon motia Gupta.
Vernacular Names
| English | Palmarosa grass, motia, rosha grass (India). |
| Vietnam | S[ar] hoa h[oof]ng. |
Geographical Distributions
Cymbopogon martini originates from the Indian subcontinent where wild stands have been exploited since antiquity and still produce an important portion of the essential oil. At the beginning of the 20th Century, C. martini was also taken into cultivation in India. In the 1930s, C. martini was introduced to Java where it yielded promising quantities of high quality oil. Production in Java grew steadily. It declined sharply during the Second World War, but was resumed on a smaller scale in the 1990s. In addition to India and Java, it is now also grown commercially in Brazil, Guatemala, Honduras, Madagascar and on a smaller scale in other African countries. In most of Southeast Asia, it is only grown occasionally.
Description
C. martini is a perennial, tufted, aromatic grass with numerous erect culms that arising from a short, stout and woody rhizome. The culm (stem) is cylindrical that can reach up to 2(-3) m tall and smooth where the lower nodes are often swollen.
The leaves are sheathing. The sheath is shorter than the internode, with tightly embracing the culm, striate, auriculate and hairless where the basal ones is looser and breaks up into fibres. The ligule is oblong, measures 1.5-4 mm long and with membrano-chartaceous. The blade is linear-lance-shaped with a long slender tip, measuring up to about 50 cm x 3 cm, cordate at the base, often amplexicaul, often scabrid at the margins, hairless where the lower surface is glaucous or pruinose and both surfaces are smooth.
The inflorescence is an erect, narrow, loose to dense, repeatedly branched panicle and measuring up to 30 cm x 5 cm. The primary axis carries 2-3 branches at each node where each of these ends in a spatheole which carries a peduncle that crowned with a pair of racemes. The spatheole is elliptical-acute when flattened, measures up to 4 cm long, orange-red and smooth or rough. The peduncle is slender and measures 1-6 mm long. The raceme is 1.5-2 cm long, which consists of 4-7 pairs of spikelets where 1 of each pair is sessile while the other is pedicellate. It is terminated by 1 sessile and 2 pedicellate spikelets. The rachis, internodes and pedicels are slender, flattened on 1 side and hairy along the margins. The sessile spikelet is cylindrical-acute, measures 3.5-4.5 mm long and hairless. The lower floret is reduced to empty lemma. The upper floret is hermaphrodite, measures 3 mm long and with a narrow lemma that bears an awn measures 12-18 mm long. The palea is absent. There are 3 stamens and 2 styles with a plumose stigma. The male pedicellate spikelet is elliptical-acute and measures 3.5-4 mm long. The lower glume is with many-veined while the upper glume is with 3-veined. The florets are reduced to a hyaline oblong scale that round the 3 stamens.
The fruit is a cylindrical to subglobose caryopsis and with basal hilum. The fruiting panicle is often turns bright red at maturity.
Ecology / Cultivation
C. martini occurs naturally and in cultivation in India from 12-32°N. It is also grown commercially from about 5°S in Java and the Seychelles to 20°S in Madagascar. It is cultivated from 150-800(-1200) m altitude. Although under natural conditions, it is often found on hillsides with an annual rainfall below 600 mm and it requires about 750 mm annual rainfall for a reasonable single harvest. If it is to be harvested several times per year, it requires at least 1500 mm annual rainfall and supplementary irrigation during periods of drought. C. martini prefers warm and sunny conditions with average daily temperatures of 20-25°C; temperatures of 25-30°C for extended periods can significantly reduce yields and suppress flowering. Frost causes damage at all growth stages and at higher elevations above ground, plant parts may die during the cool season. Even slight frost at harvesting can be devastating and may reduce yields by half. Long days seem to favour oil production, both in quantity and in geraniol content.
In its natural habitat, C. martini grows on poor which is often slightly alkaline soils (pH 7.5-8.5) of sandy-loamy to loamy texture. Soils rich in organic matter and nitrogen are reported to yield high quality oil. In Orissa, India, it is found on slightly saline soils. In cultivation, fertile and well-drained soils of pH 6-7 are considered optimum. On alkaline soils (pH 8.5 or higher), the growth and yields are reduced, but oil quality is not affected. C. martini does not tolerate acid soils or waterlogging. Ginger grass is more tolerant of prolonged periods of heavy rain that saturate the soil and also of imperfectly drained soils.
Line Drawing / Photograph
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References
- Plant Resources of South-East Asia No. 19: Essential-oil plants.
