Running Mountaingrass: A Tropical Ground Cover Worth Considering
If you’re looking for a low-maintenance grass that thrives in shady spots, running mountaingrass might catch your eye. This perennial grass has found its way into tropical gardens across the Pacific, though it comes with some considerations worth exploring before you decide to plant it.
What is Running Mountaingrass?
Running mountaingrass (Oplismenus compositus) is a perennial grass that’s part of the larger grass family. You might also see it listed under its scientific synonym, Panicum compositum. As its common name suggests, this grass has a spreading habit that allows it to run across the ground, making it useful as a ground cover option.
Where Does It Come From?
Here’s where things get interesting: running mountaingrass is native to the Pacific Basin region, but it’s considered non-native in Hawaii. It has established itself naturally in Hawaii, Guam, and Palau, where it reproduces on its own and tends to stick around once it’s settled in.
The Garden Appeal
Running mountaingrass brings a subtle, naturalistic look to gardens. Its delicate appearance and spreading growth habit make it suitable for:
- Understory plantings beneath trees
- Ground cover in shaded areas
- Naturalized garden settings
- Tropical and subtropical landscapes
Don’t expect showy flowers – like many grasses, it produces inconspicuous flower spikes that are more functional than decorative.
Growing Conditions and Care
If you’re in USDA hardiness zones 10-12, running mountaingrass can be a relatively easy addition to your garden. Here’s what it prefers:
- Light: Shade to partial shade (perfect for those tricky dark corners)
- Soil: Moist, well-draining soil
- Maintenance: Low once established
- Spread: Spreads by runners, so give it room to roam
Wetland Considerations
Interestingly, running mountaingrass shows different wetland preferences depending on location. In the Caribbean region, it’s classified as an Obligate Upland plant, meaning it almost never occurs in wetlands. However, in Hawaii, it’s considered Facultative Upland, meaning it usually grows in non-wetland areas but can occasionally pop up in wetlands too.
Wildlife and Pollinator Value
As a wind-pollinated grass, running mountaingrass doesn’t offer much direct benefit to pollinators like bees and butterflies. However, grasses can provide habitat and nesting material for various wildlife species, though specific benefits for this species aren’t well-documented.
Should You Plant It?
Running mountaingrass sits in that middle ground – it’s not native to Hawaii, but it’s not currently listed as invasive or noxious either. If you’re considering it for your garden, here are some things to think about:
Consider it if: You need a low-maintenance ground cover for shady areas in tropical zones, and you’re okay with a spreading grass that naturalizes easily.
Think twice if: You’re committed to using only native plants in your landscape design.
Native Alternatives to Consider
If you’d prefer to stick with native options, consider researching native grasses and ground covers specific to your region. Local native plant societies and extension offices can provide excellent recommendations for indigenous alternatives that provide similar garden functions while supporting local ecosystems.
The Bottom Line
Running mountaingrass can be a practical choice for specific garden situations, particularly if you need something that thrives in shade and spreads to cover ground. Just remember that introducing any non-native plant comes with responsibility – monitor its spread and be prepared to manage it if needed. When in doubt, native alternatives are always the most ecologically sound choice for supporting local wildlife and maintaining regional ecosystem balance.
