Hawaii is known globally for its dramatic topography and incredible biodiversity. The islands contain nearly all of the world’s major climate zones, ranging from wet tropical rainforests to arid deserts and even polar tundra at the highest elevations. This diverse climate created a unique ecosystem, but much of the plant life seen today is not native. Due to centuries of human activity, including agriculture and ranching, the vast majority of grasses covering the islands are non-native species, with over 200 introduced varieties establishing themselves.
The Most Common Turf and Lawn Varieties
The warm, tropical climate allows for the cultivation of specific turfgrass varieties that maintain a lush, green appearance year-round. These warm-season grasses are chosen for their ability to withstand intense sun, high temperatures, and diverse soil conditions. Many select Zoysia grass for its dense texture and durability, allowing it to handle significant foot traffic while remaining drought-tolerant. Varieties like ‘El Toro’ or ‘Zeon’ are popular in residential areas and tolerate some shade, making them versatile.
For properties near the coast, Seashore Paspalum (Paspalum vaginatum) is utilized due to its tolerance for both salt spray and brackish irrigation water. This variety provides a fine-textured, deep green lawn that thrives in full sun and is common on beachfront resorts and golf courses. Bermuda grass (Cynodon dactylon) is also a common choice, particularly for athletic fields and golf course fairways, due to its rapid growth, resilience, and ability to recover quickly from wear.
In areas that block sunlight, St. Augustine grass (Stenotaphrum secundatum) is often preferred because it is the most shade-tolerant warm-season variety. This grass features a coarse, broad leaf blade and a creeping growth habit, creating a thick turf. St. Augustine requires moderate to high water levels and is sometimes susceptible to pests like the Southern Chinch Bug.
Aggressive Invasive Grasses Dominating Natural Landscapes
In stark contrast to manicured lawns, a different group of non-native grasses has aggressively colonized unmanaged fields and dry, natural areas. These invasive species now cover approximately one-third of the state’s land area and pose a significant ecological threat. Following the closure of large agricultural operations, such as sugar cane plantations, abandoned land allowed these resilient grasses to establish dominance.
The most notorious species are Fountain Grass (Cenchrus setaceus), Guinea Grass (Megathyrsus maximus), and Buffel Grass (Cenchrus ciliaris), all native to Africa or the Mediterranean. These grasses grow rapidly during wet seasons and produce fine, dry fuel that becomes highly flammable during subsequent dry periods. This cycle has dramatically altered the islands’ fire ecology, with the annual area burned by wildfires quadrupling in recent decades.
These invasive grasses increase the frequency and intensity of wildfires, particularly in the drier, leeward regions. They are adapted to thrive with fire, recovering faster than the native woody plants they replace. This creates a feedback loop where fire promotes more grass, which promotes more fire. Fountain Grass alone covers an estimated 200,000 acres on Hawaiʻi Island, and Buffel Grass has high fire-risk ratings, capable of burning even when it appears green.
The Rare Endemic Grasses of Hawaii
The original Hawaiian landscape featured a small number of native grass species before human contact, as extensive grasslands were uncommon and restricted to coastal dunes or high-elevation slopes. Today, grasses are the most diverse plant family in the islands, but the vast majority are introduced, leaving native grasses extremely rare. These remaining endemic grasses are confined to remote or protected habitats, such as wet montane forests and subalpine zones.
One example is Hawaiian bluegrass (Poa sandvicensis), an endangered perennial grass that grows in densely tufted clumps on wet, shaded slopes at elevations between 3,200 and 4,200 feet. Another is Agrostis sandwicensis, a species found only in the state that faces threats from hybridization with introduced species. The primary conservation challenge for these rare species is the overwhelming competition from aggressive non-native grasses that invade and degrade their specialized habitats.