Axonopus compressus is a creeping stoloniferous grass that grows close to the ground, hardly reaching more than 15 cm tall. It spreads by above-ground runners and short underground rhizomes.
You can identify Pearl Grass by its flat or folded, shiny, green to light green foliage and fairly low, dense mats.
Pearl Grass Classification
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Tracheophyta
- Subphylum: Angiospermae
- Class: Monocotyledonae
- Order: Poales
- Family: Poaceae
- Genus: Axonopus
- Species: Axonopus compressus
- Common Names: Carpet Grass, Broadleaved Carpetgrass, Tropical Carpet Grass, Blanket Grass, American Carpet Grass, Taiwan Grass, Taipei Grass, and Thai Grass
Nativity and Distribution
Pearl Grass is native to Mexico and South American countries like Brazil, Argentina, Belize, Colombia, Ecuador, and Venezuela.
It has since been introduced in other regions, including North America, the Caribbean, Central America, Africa, Asia, Australia, and the Pacific Islands.
Physical Characteristics
- Leaves: Broadly oblong, blunt, shiny, light green to green
- Fruits: Ovoid or lanceloid, about 2-3.5 mm long spikelets
- Stems: Slender, low-growing, about 15 cm, flowering culms 30-60 cm tall
- Flowers: A panicle comprising 2-3 spike-like racemes
- Roots: Fibrous root system
Pearl Grass is a creeping, stoloniferous grass that grows not more than 15 cm tall. It is commonly known as Carpet Grass.
It is easily identifiable by its dense, ground-hugging foliage and light green to green, flat or folded, and shiny leaves.
The sheath is loose, strongly compressed, and keeled, and often glabrous or with some hair on the outer margin. The leaves are broadly oblong, flat or folded, 2-16 cm long and 4-18 mm wide.
They may be glabrous or hairy on the upper surface, with fine hairs on the margins with fine hairs, and acute to obtuse tips. The young grass leaves are light green and turn green in maturity.
Stems are creeping, typically growing to 15 cm tall. However, when flowering, the culms grow erect to a height of about 30-60 cm tall. The nodes on culms are flattened, glabrous, or pubescent.
Inflorescence is a panicle consisting of slender, 2-3, spike-like racemes. The spikelets are solitary, sessile, lanceolate, and about 2-3.5 mm long and 1-1.2 mm wide. Flowering timelines vary based on the environment, but typically occur throughout the growing season.
The seed is elliptical, obtuse, 1-5 mm long, and yellow-brown in color.
Reproduction, Dispersal, and Life Cycle
- Life Cycle: Perennial
- Seeds: It is a poor seed producer
- Climate: Tropical and subtropical climates
- Dispersal: Water, wind, animals, and contaminated soil
Axonopus compressus behaves as a perennial grass and thrives in tropical and subtropical climates. The grass can produce a few seeds that are often dispersed by water, wind, animals, or contaminated produce or machinery.
However, it primarily spreads vegetatively by stolons (above-ground creeping stems), which root at the nodes and short underground rhizomes. This allows for rapid colonization of new areas or recovery after disturbance or grazing.
The grass prefers shady areas and moderately drained sandy loam soils. That said, it can also grow well in light clay and acidic soils. It has low salinity tolerance and waterlogged or swampy conditions.
Similar Plants
- Axonopus fissifolius
- Paspalum conjugatum
- Chrysopogon aciculatus
Uses
- The grass is used as a permanent pasture for grazing livestock due to its high grazing tolerance
- It is a popular turf grass for residential lawns, parks, and low-maintenance, non-elite sports fields.
- It is planted as a soil cover in rubber, oil palm, and coffee plantations where shade is heavy to achieve weed suppression.
- The grass is used for soil stabilization and erosion control.
Impact on Farms and Environment
While Pearl Grass can provide good ground cover, maintain soil structure, and suppress weed growth, in some settings, it can become a troublesome weed itself.
For instance, it can invade lawns, roadsides, and other disturbed sites, outcompeting desirable plants or turf.
Since it has low nutritive value as it matures, it requires heavy grazing to keep it in its vegetative and nutritive stage. Otherwise, if left to dominate a pasture when mature, it can lead to reduced animal weight and eventual economic losses.
Due to its efficient propagation and dense low-growth, it has the potential to shade out lower-growing plants, altering native biodiversity.
Control
- Cultural control: Grazing and improving soil fertility
- Mechanical control: Pulling or tillage
- Chemical control: Herbicides like MSMA, bentazon, and metsulfuron-methyl
Frequent grazing can keep the grass short and prevent seed set, thereby reducing its vigor and spread. Frequent defoliation also limits stolon growth.
Improving the nutrient status of a desired grass and reducing soil acidity can make Pearl Grass less competitive, gradually leading to its decline. Improving sun penetration can also provide the same effect since it thrives in shaded areas.
Hand-pulling is only viable for small infestations and if all the nodes are removed. Repeated tillage can cut off the stolon network, reducing the grass cover.
Herbicides indicated for Axonopus compressus removal include MSMA, DSMA, prodiamine, glufosinate, bromoxynil, glyphosate, and metsulfuron-methyl. Consult a local extension expert on the best herbicide for your area of concern.
Lead Editor for Insight Weeds.