Poaceae
Imperata

Imperata cylindrica (L.) Raeusch.

First published in Nomencl. Bot. Pl. Illustr., ed. 3: 10 (1797)
This species is accepted
The native range of this species is Medit. to Africa and Afghanistan. It is a perennial or rhizomatous geophyte and grows primarily in the temperate biome.

Descriptions

Kew Species Profiles

General Description
Alang-alang is considered one of the ten worst weeds in the world, but has many uses as a traditional medicine.

Imperata cylindrica, or alang-alang, is regarded as a very serious weed in tropical countries. It spreads by scaly rhizomes and can invade and over-run any disturbed ecosystem, including cultivated fields. It is very difficult to eradicate.

Species Profile
Geography and distribution

Alang-alang is native to Asia, Micronesia, Australasia, Europe, southeast USA, Mexico and Africa and is estimated to cover 2,000,000 square kilometres (including natural grasslands) throughout the tropics.

Description

Imperata cylindrica is perennial, with basal leaves 3-100 cm long, 2-20 mm wide and stiff with scabrous leaf-blade margins. The flowering head is loosely cylindrical with abundant white silky hairs concealing the flowering parts.

Uses

Alang-alang is used in land reclamation and for soil erosion control on account of its vigorous, rhizomatous habit. However, these same characteristics make it a serious invasive species in pastures, abandoned cultivation and deforested areas throughout the tropics and subtropics and is considered by IUCN's Invasive Species Specialist Group as one of the world's worst weeds.

The stems of Imperata cylindrica are used as thatch, the stems and leaves for making ropes, and its fibres are used to make paper. In southeast Asia and Africa alang-alang is used in traditional medicine for treating a wide range of ailments.

Its rhizome is used for treating blood system disorders, nausea, indigestion and jaundice. In China the rhizome is used as a diuretic, a restorative tonic, and to stop bleeding; in southeast Asia it is used for treating diarrhoea and dysentery. In Namibia, the stems are ground into a powder used as a cosmetic, and also cut into pieces and strung for decorations. Alang-alang is generally regarded as having poor forage value.

Millennium Seed Bank: Seed storage

Kew's Millennium Seed Bank Partnership aims to save plant life world wide, focusing on plants under threat and those of most use in the future. Seeds are dried, packaged and stored at a sub-zero temperature in our seed bank vault.

Number of seed collections stored in the Millennium Seed Bank: Ten

Seed storage behaviour: Orthodox (the seeds of this plant survive being dried without significantly reducing their viability, and are therefore amenable to long-term frozen storage such as at the MSB)

Germination testing: Successful

Distribution
Australia, Mexico
Ecology
Seasonally wet places and alongside streams; a common and aggressive weed of disturbed places and cultivated fields.
Conservation
Considered by IUCN to be one of the world's worst weeds.
Hazards

Not recorded

[KSP]

Extinction risk predictions for the world's flowering plants to support their conservation (2024). Bachman, S.P., Brown, M.J.M., Leão, T.C.C., Lughadha, E.N., Walker, B.E. https://nph.onlinelibrary.wiley.com/doi/full/10.1111/nph.19592

Conservation
Predicted extinction risk: not threatened. Confidence: confident
[AERP]

Morphology General Habit
Perennial. Rhizomes elongated; scaly. Culms erect; 10-120 cm long. Leaves mostly basal. Ligule a ciliolate membrane. Leaf-blades erect; flat, or convolute; 3-100 cm long; 2-20 mm wide; stiff. Leaf-blade margins scabrous.
Morphology Reproductive morphology Inflorescences
Inflorescence a panicle with branches tipped by a raceme. Panicle spiciform; linear; 3-22 cm long. Primary panicle branches accrescent to a central axis; with evident branchlets on axis. Racemes bearing few fertile spikelets. Rhachis tough; subterete. Rhachis internodes filiform. Spikelets in pairs. Fertile spikelets pedicelled; 2 in the cluster. Pedicels filiform; unequal.
Morphology Reproductive morphology Inflorescences Spikelets
Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets lanceolate; subterete; 2.2-6 mm long; falling entire. Spikelet callus bearded; base truncate. Spikelet callus hairs white; 2-3 length of spikelet.
Fertile
Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets lanceolate; subterete; 2.2-6 mm long; falling entire. Spikelet callus bearded; base truncate. Spikelet callus hairs white; 2-3 length of spikelet.
Morphology Reproductive morphology Inflorescences Bracts Glume
Glumes similar; exceeding apex of florets; firmer than fertile lemma. Lower glume oblong; 1 length of spikelet; membranous; without keels; 5-7 -veined. Lower glume surface villous; hairy below. Lower glume apex obtuse. Upper glume oblong; 2.2-6 mm long; membranous; without keels; 5-7 -veined. Upper glume surface villous; hairy below. Upper glume apex obtuse.
Morphology Reproductive morphology Flowers Florets
Basal sterile florets barren; without significant palea. Lemma of lower sterile floret similar to fertile lemma; oblong; 0.5 length of spikelet; hyaline; 0 -veined; without midvein; without lateral veins; ciliolate on margins; erose; obtuse. Fertile lemma ovate; 1 mm long; hyaline; without keel; 0 -veined. Lemma apex acute. Palea hyaline; 0 -veined; without keels.
Morphology Reproductive morphology Flowers
Lodicules absent. Anthers 2; 3-5 mm long. Stigmas 2; terminally exserted.
Distribution
Europe: southwestern and southeastern. Africa: north, Macaronesia, west tropical, west-central tropical, northeast tropical, east tropical, southern tropical, south, and western Indian ocean. Asia-temperate: Soviet Middle Asia, Caucasus, western Asia, Arabia, China, and eastern Asia. Asia-tropical: India, Indo-China, Malesia, and Papuasia. Australasia: Australia and New Zealand. Pacific: southwestern and northwestern. North America: southeast USA and Mexico.
Reference
Andropogoneae. FTEA.
[GB]

Uses

Use
Land reclamation, soil erosion control, thatch, ropes, paper, traditional medicine, cosmetics.
[KSP]

Common Names

English
Alang-alang, Japanese Blood Grass

Sources

  • Angiosperm Extinction Risk Predictions v1

    • Angiosperm Threat Predictions
    • http://creativecommons.org/licenses/by/4.0

  • GrassBase - The Online World Grass Flora

    • Clayton, W.D., Vorontsova, M.S., Harman, K.T. and Williamson, H. (2006 onwards). GrassBase - The Online World Grass Flora.
    • http://creativecommons.org/licenses/by-nc-sa/3.0

  • Herbarium Catalogue Specimens

    • Digital Image © Board of Trustees, RBG Kew http://creativecommons.org/licenses/by/3.0/

  • Kew Backbone Distributions

    • The International Plant Names Index and World Checklist of Vascular Plants 2024. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2023 World Checklist of Vascular Plants. http://creativecommons.org/licenses/by/3.0

  • Kew Living Collection Database

    • Common Names from Plants and People Africa http://www.plantsandpeopleafrica.com/

  • Kew Names and Taxonomic Backbone

    • The International Plant Names Index and World Checklist of Vascular Plants 2024. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2023 International Plant Names Index and World Checklist of Vascular Plants. http://creativecommons.org/licenses/by/3.0

  • Kew Science Photographs

    • Copyright applied to individual images

  • Kew Species Profiles

    • Kew Species Profiles
    • http://creativecommons.org/licenses/by-nc-sa/3.0

  • Plants and People Africa

    • Common Names from Plants and People Africa http://www.plantsandpeopleafrica.com/
    • © Plants and People Africa http://www.plantsandpeopleafrica.com http://creativecommons.org/licenses/by/3.0/