Axonopus Compressus (Blanket Grass)

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Blanket grass, scientifically known as Axonopus compressus, is a perennial rhizomatous plant that is shallow-rooted and stoloniferous. 

The plant’s foliage generally reaches up to 15 cm high, and its flowering culms are up to 30-45 cm high.

Axonopus compressus is mainly found along roadsides and in disturbed or shaded regions of tropical and subtropical areas.

Scientific Classification

  • Kingdom: Plantae
  • Subkingdom: Tracheobionta
  • Division: Magnoliophyta
  • Class: Liliopsida
  • Subclass: Commelinidae
  • Order: Cyperales
  • Family: Poaceae 
  • Genus: Axonopus P. Beauv.
  • Species: Axonopus compressus 
  • Common Names: broadleaf carpet grass, tropical carpet grass, lawn grass, Louisiana grass, carpet grass, savannah grass, Kearsney grass 

Nativity and Distribution

 Axonopus compressus is a native of the Americas (South, Central, and North America). The plant is also found in the following areas:

  • West Africa
  • South Africa
  • South-East Asia
  • Pacific Islands
  • Australia

Physical Appearance

The plant's stems grow horizontally along the ground surface forming a blanket
The plant’s stems grow horizontally along the ground surface, forming a blanket. Image: tropicalforages.info/chrisgardiner
  • Leaves: Arranged alternatively on the stem.
  • Flowers: Yellow, orange, and red in color. 
  • Stem: Compressed and flattened stems. 
  • Fruit: Small fruits that are a caryopsis.
  • Roots: Fibrous root system.

Blanket grass leaves are oblong and linear, with smooth surfaces on both sides. The leaves are 4-15cm long and 2.5-15mm wide.

The plant’s stems grow horizontally along the soil surface, contributing to its mat-forming nature. 

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Foliage typically grows to a height of 15 cm, while flowering stems can reach heights of 30 to 45 cm.

The flowering stems bear racemose panicles (branched inflorescences with flowers arranged along the branches). The plant has 2-3 racemes, though up to 5 are possible. 

The 2 upper racemes are paired together on a slender peduncle (flower stalk) and are usually situated on one side. 

Life Cycle/Reproduction/Dispersal

  • Life Cycle: Perennial.
  • Seeds: 2mm long caryopsis. 
  • Climate: Prefers tropical and subtropical climates.
  • Dispersal: Winds are animals.

Under optimal conditions, blanket grass grows more rapidly through vegetative means than by seed dispersal.

This asexual reproduction occurs through tillers that develop from adventitious buds on culm nodes, as well as through stolons and rhizomes. 

Sexual reproduction includes the processes of flowering, pollination, and seed formation.

When conditions are favorable, the seeds dispersed germinate, leading to the growth of new plants. This process allows the species to spread to new areas and maintain its population.

Uses

Blanket grass is usable in the following ways:

1. Prevents Soil Erosion

Axonopus compressus is used in soil stabilization. Its thick growth helps stabilize the soil, minimizing runoff during heavy rainfall.

Additionally, it is used to prevent soil erosion in rubber, palm oil, and coconut plantations, where it is sown together with these plants.

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2. Turf and Forage

Blanket grass is a slow-growing species that can tolerate heavy grazing pressure, making it suitable for use as a permanent pasture. 

It is commonly used as a turf and forage grass in humid tropical and subtropical regions, such as West Africa, South Africa, India, and the Philippines. 

3. Soil Cover in Tree Plantations

It facilitates reduced use of herbicides when used as a soil cover in tree plantations.

Impact on the Environment

The thick layer of grass can compress the soil reducing its permeability and capacity to sustain other plant species
The thick layer of grass can compress the soil, reducing its permeability and capacity to sustain other plant species. Image: Canva/kwanchaichaiudom

Carpet grass can outcompete native plants, resulting in decreased biodiversity. This may disturb local ecosystems, as native plants offer crucial habitats for wildlife. 

Although blanket grass can aid in erosion control, its overgrowth can cause soil deterioration. Over time, the thick layer of grass can compress the soil, reducing its permeability. 

This can hinder water absorption and diminish the soil’s capacity to sustain other plant species, ultimately impacting soil health and fertility.

Control

The following are effective methods for controlling Axonopus compressus:

1. Chemical Control

Celsius WG Herbicide is effective for controlling blanket grass. Other herbicides that can be used are:

  • Glyphosate: A non-selective herbicide often used in mixtures with Dicamba to enhance its efficacy.
  • Metsulfuron-methyl: This is an effective treatment for controlling carpet grass in various agricultural trials.
  • Paraquat: Often used in mixtures with Diuron.
  • Diuron: It has effectively controlled carpet grass at higher application rates, especially in tea and bananas.
  • Fluroxypyr: Has been found effective against carpet grass, particularly in oil palm plantations.
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2. Natural Control Methods

  • Water with salt: Watering with saltwater can easily increase soil salinity, which kills  Axonopus compressus. To prepare the solution, mix 2 cups of table salt into 7-10 gallons of water.
  • Use white vinegar: Applying undiluted white vinegar directly to patches of carpet grass can effectively kill it. 
  • Sprinkle baking soda: Exercise caution, as baking soda can stress other nearby plants.
  • Apply borax: Simply scatter a handful of boric acid over the affected areas. After a few days, the grass should die off, allowing for easy raking and removal from your lawn.
  • Raise soil pH: Carpet grass prefers an acidic pH range of 5-6. By raising the soil pH to around 7.5, you can create an unfavorable environment for carpet grass, making it less likely to thrive.

3. Mechanical Control Methods

Mechanical control methods such as mowing and hand weeding effectively control blanket grass.