RANK

PLANT

IMPACT/AREA COVERED

DESCRIPTION

1

Water Hyacinth (Eichhornia crassipes)

Covers over 20,000 sq. miles globally

One of the most invasive aquatic plants, clogging waterways and altering entire aquatic ecosystems.

2

Kudzu (Pueraria montana)

Over 7 million acres (U.S. Southeast)

Known as "the vine that ate the South," it rapidly smothers native vegetation and structures.

3

Lantana (Lantana camara)

Over 5 million acres (Australia, Africa)

Forms dense thickets, reduces biodiversity, and invades agricultural areas.

4

Japanese Knotweed (Fallopia japonica)

137,000 sq. miles (UK, Europe, N. America)

An aggressive perennial that spreads quickly and damages infrastructure and natural habitats.

5

Privet (Ligustrum spp.)

Over 3 million acres globally

An invasive hedge plant that displaces native species and dominates forest edges and wetlands.

6

Cogon Grass (Imperata cylindrica)

Over 500,000 acres (Southeast U.S., tropical Asia)

Invades forests, outcompetes native flora, and increases wildfire risks.

7

Purple Loosestrife (Lythrum salicaria)

2.5 million acres (North America)

Invades wetlands, alters water flow, and reduces native plant diversity.

8

Tree of Heaven (Ailanthus altissima)

Thousands of acres (N. America, Europe)

A fast-growing tree that disrupts urban environments and natural ecosystems.

9

Bamboo (Phyllostachys spp.)

Over 1 million acres globally

Some bamboo species spread aggressively, forming dense thickets that outcompete other plant species.

10

Giant Hogweed (Heracleum mantegazzianum)

31,000 sq. miles (Europe, N. America)

A hazardous plant with toxic sap, disrupting ecosystems and causing health risks to humans.