Rock Rosemary: A Rare Native Gem for Southern Gardens
Meet rock rosemary (Merremia quinquefolia), one of those delightfully mysterious native plants that makes botanists scratch their heads and gardeners wonder what exactly am I looking at? This perennial herb is like the quiet kid in the back of the class – unassuming but potentially fascinating once you get to know it.
What Exactly Is Rock Rosemary?
Don’t let the name fool you – rock rosemary isn’t actually related to the Mediterranean herb you might sprinkle on your roasted potatoes. Merremia quinquefolia belongs to the morning glory family and is what botanists call a forb herb. Think of it as a non-woody perennial that keeps its growing points at or below ground level, making it a true survivor in challenging conditions.
This native plant was previously known by the synonym Ipomoea quinquefolia, so if you stumble across that name in older gardening references, you’re looking at the same plant.
Where Does Rock Rosemary Call Home?
Rock rosemary is a true Southern belle, native to a very limited range that includes Florida, Puerto Rico, the U.S. Virgin Islands, and Navassa Island. It’s one of those plants that decided the tropical and subtropical Caribbean region was perfect and never felt the need to venture much further north.
The Mystery Plant Challenge
Here’s where things get interesting (and a bit frustrating for us gardening enthusiasts): rock rosemary is so rare and understudied that we honestly don’t know much about its specific growing requirements, wildlife benefits, or ideal garden applications. It’s like trying to write a recipe when you’ve only seen the finished dish once!
What we do know is that it’s a perennial herb without significant woody growth, suggesting it might work well in herbaceous borders or naturalized areas. Given its native range in tropical and subtropical regions, it likely appreciates warm temperatures year-round.
Should You Try Growing Rock Rosemary?
This is where we enter uncharted territory. While rock rosemary is native and not listed as invasive or noxious, its extreme rarity means:
- Finding seeds or plants may be nearly impossible
- Growing requirements are largely unknown
- Its role in garden ecosystems is unclear
- Pollinator and wildlife benefits are undocumented
If you’re in Florida or other parts of its native range and happen to encounter this plant (lucky you!), it would be worth observing and potentially photographing to contribute to our understanding of this mysterious species.
Better Native Alternatives
Since rock rosemary is so difficult to source and grow, consider these well-documented native alternatives for Southern gardens:
- Beach morning glory (Ipomoea pes-caprae) for coastal areas
- Railroad vine (Ipomoea pes-caprae) for sandy soils
- Wild potato vine (Ipomoea pandurata) for inland areas
These relatives offer similar morning glory family characteristics with the bonus of being better understood and more readily available.
The Bottom Line
Rock rosemary represents one of those fascinating gaps in our native plant knowledge. While we can’t provide specific growing instructions or guarantee garden success, it serves as a reminder that there are still botanical mysteries waiting to be solved, even in our own backyards. For now, it’s probably best admired from afar and left to the specialists working to understand and conserve rare native species.
If you’re passionate about growing truly native plants in Florida and the Caribbean, focus on the many well-documented species that we know will thrive in gardens while supporting local ecosystems. Sometimes the best way to honor rare plants like rock rosemary is to make sure their better-known cousins have a place to flourish.
