Imperata cylindrica is a perennial Rhizomatous grass that usually grows in tropical and subtropical climates. It is a tall-growing grass that can reach up to 3m tall.
You can identify cogon grass by its clumping growth pattern and fluffy, silvery-white seed heads.
Cogon Grass (Imperata cylindrica) Scientific Classification
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Spermotophyta
- Subphylum: Angiospermae
- Class: Monocotyledonae
- Order: Cyperales
- Family: Poaceae
- Genus: Imperata
- Species: Imperata cylindrica
- Varieties: I. cylindrica var. major; I. cylindrica var. latifolia; I. cylindrica var. africana; I. cylindrica var. europa.
- Common Names: cogon grass (cogongrass), kunai grass, spear grass, sword grass, cotton wool grass, thatch grass, blady grass, Japanese bold glass, silver spike, and bedding grass
Nativity & Distribution
Cogon grass is native to tropical and sub-tropical areas of:
- Asia
- Africa
- Australia
- Southern Europe
- Micronesia
- Melanesia
It is also a widely distributed species worldwide, including in Latin America, the Southern United States, and the Caribbean.
Physical Characteristics
- Leaves: Large, stiff leaves with a sharp, pointed apex.
- Fruits: Large fuzzy seed heads with a cottony to silky appearance.
- Stems: A tall, firm stalk reaching up to 3m tall.
- Flowers: Long, cylindrical, and silvery-white flower heads.
- Roots: Rhizomatous root system.
Imperata cylindrica is a perennial, colony-forming grass with erect stalks reaching 3m tall. You can easily identify it by its dense, clumping growth habit and fluffy, silvery-white seed heads.
Cogon grass has firm, erect stalks with nodes covered with long, white hairs. In young plants, the stalks are usually hidden—covered by the leaf blades.
It has large leaves (about 12-80 cm long), wide at the base (about 2cm wide), and narrow at the apex with a sharp, pointed tip. The leaves are usually yellowish green but turn red, tan, or orange in winter.
The leaf blades have finely toothed margins, and both surfaces are hairless (some leaves are slightly hairy at the base). The margins and the leaf surfaces are embedded with silica crystals, giving them a coarse texture.
Imperata cylindrica has fluffy, silvery-white flower heads that form at the tip of the stalks. The flower heads are long, cylindrical, and can grow 2-8 inches long.
The flowers bloom from late March to mid-June (though the blooming period may vary from place to place depending on the local climate).
Reproduction, Dispersal, & Life Cycle
- Life Cycle: Perennial
- Seeds: Can produce up to 3,000 seeds
- Climate: Grows well in tropical and subtropical regions or areas with a warm climate.
- Dispersal: Wind-dispersed seeds.
Cogon grass produces dandelion-like seeds, which are silky with white hairs. The hairy nature allows the seeds to be dispersed by wind over long distances.
While wind is the main dispersal method, seeds can also be carried by water or spread by vehicles, animals, shoes, farm machinery, and contaminated soil.
The grass is a prolific seeder, with each plant producing around 3,000 seeds. The seeds are highly viable, with up to 95% of the produced seeds germinating when they land on bare soil.
The seeds can germinate within a week of being harvested (dispersed) and remain viable for up to a year.
Imperata cylindrica’s main mode of reproduction is sexual via seeds. However, the plant also reproduces vegetatively through rhizomes.
The plant has a dense rhizome root system that grows as deep as four feet and spreads far and wide. A single rhizome node can produce up to 350 new shoots, which helps the grass form a thick, dense ground cover.
Uses
- It is used as fodder for animals.
- It is used for thatching the roofs of traditional houses in some Asian regions.
- Some colourful varieties of grass are cultivated as ornamental plants.
- It can be used as an alternative raw material for paper-making.
- It can be used in weaving to make bags and mats.
- Its used as a ground cover crop and for stabilizing the soil to prevent erosion.
- It is edible. Its young shoots and inflorescence can be cooked, while the roots can be chewed for their starch and high sugar content.
- It is used in traditional medicine to treat a variety of health conditions.
Impact on Farms and Environment
Despite its numerous uses, Imperata cylindrica is a highly invasive weed species affecting lawns, gardens, crop fields, forest areas, roadsides, and several other areas.
It is an aggressive grass that spreads quickly through prolific seeding and rhizomatous roots. It also produces a phenolic compound that can inhibit the growth and survival of other plants.
In addition, the dense ground cover formed by the plant can choke most surrounding vegetation. Therefore, cogon grass can quickly infest new areas, outcompeting native or cultivated plants for resources.
Due to its highly invasive nature, Cogon grass is listed as a noxious weed in the United States at both state and federal levels. It is also considered a weed in more than 70 countries worldwide.
Despite being a weed problem, Cogon grass is also a fire hazard. Due to its thick, dense ground cover, the grass has a very high biomass, causing it to burn at very high temperatures.
The grass is highly flammable all year round, especially around winter when it is dry. However, drought conditions during the dry season can turn it into a wildfire hazard.
Control
- Natural methods: hand-pulling, digging, mowing, and burning.
- Chemical control: it can be controlled using chemical herbicides like imazapyr, daplon, glufosinate, and glyphosate.
The first line of defense when dealing with cogon grass is prevention. This can include planting ground cover crops, avoiding soil disturbance, and stopping destructive practices such as timber harvesting and field burning that can leave areas prone to infestation.
If an infestation has already occurred, you can control cogon grass through natural solutions like hand-pulling and digging with gardening tools (for young shoots).
More aggressive tactics, such as mowing and field burning, can be effective for large infestations. However, due to the dense root system, the grass will grow back; therefore, repeated treatment (or accompanying with other solutions like chemical control) is needed.
Note: Due to the deep rhizome roots, weed control practices such as plowing are not advisable. Such practices can disturb the soil and spread parts of the root rhizomes, leading to further infestation.
Chemical herbicides like glyphosate, glufosinate, imazapyr, daplon, and others prescribed by professionals are the best control solutions for cogon grass. Non-selective herbicides like glyphosate are especially effective when dealing with large, stubborn infestations.
Selective herbicides, such as fluazifop-P-butyl, can also be used in areas with crops or if you are worried about killing native vegetation.
Due to the deep rhizome root system, a single application of chemical herbicides may not eradicate the weed. Therefore, several treatments are advised to completely overwhelm the plant.
Lead Editor for Insight Weeds.