Silkrubber (Funtumia elastica): A Tropical Shrub with Limited Appeal
If you’ve stumbled across the name silkrubber in your plant research, you might be wondering what this unusual-sounding shrub is all about. Funtumia elastica, commonly known as silkrubber, is a tropical shrub that’s made its way to Puerto Rico, though it’s not exactly what you’d call a garden superstar.
What Is Silkrubber?
Silkrubber is a perennial shrub that typically grows as a multi-stemmed woody plant, usually staying under 13 to 16 feet in height. Like many shrubs, it develops several stems from near the ground, giving it a bushy appearance. The plant gets its quirky common name from the white, latex-like sap it produces when cut or damaged—hence the rubber part of its name.
Where Does Silkrubber Come From?
Here’s where things get interesting: while silkrubber has established itself in Puerto Rico, it’s actually not native to the area. This tropical African native has been introduced and now reproduces on its own in Puerto Rican landscapes. Currently, Puerto Rico appears to be the only U.S. territory where this plant has established itself.
Should You Plant Silkrubber?
The short answer? Probably not, and here’s why:
- Limited availability: Since it’s only established in Puerto Rico, finding this plant elsewhere can be challenging
- Non-native status: As a non-native species, it doesn’t support local ecosystems the way indigenous plants do
- Unknown wildlife value: There’s limited information about how silkrubber benefits local pollinators or wildlife
- Climate restrictions: It only thrives in very warm, tropical conditions (USDA zones 10-12)
Growing Conditions and Care
If you’re in Puerto Rico or another tropical location and still want to try growing silkrubber, here’s what you need to know:
Climate Requirements: This plant is strictly for tropical and subtropical gardens. It needs consistently warm temperatures and won’t survive any frost or freezing conditions.
Soil and Water: Silkrubber prefers well-draining soil but needs consistent moisture. Think tropical rainforest conditions—humid but not waterlogged.
Maintenance: Regular pruning will help maintain its shape and size, especially since it can grow quite tall under ideal conditions.
Better Alternatives for Your Garden
Instead of silkrubber, consider these native alternatives that will better support your local ecosystem:
- If you’re in Puerto Rico, look for native shrubs like Psychotria berteriana (wild coffee) or Cordia borinquensis (Puerto Rican manjack)
- For mainland U.S. gardeners seeking tropical-looking shrubs, consider native options in your specific region
The Bottom Line
While silkrubber isn’t necessarily harmful, it’s also not particularly beneficial for most gardeners. Its limited range, non-native status, and lack of known ecological benefits make it a less-than-ideal choice for sustainable gardening. Your garden—and local wildlife—will likely benefit more from native plant selections that support the natural ecosystem in your area.
If you’re passionate about unusual tropical plants and happen to live in a suitable climate, silkrubber might satisfy your curiosity. Just remember that every plant choice is an opportunity to support local biodiversity, so native species should always be your first consideration.
