MacCart’s Swallow-wort: A Mysterious Texas Native Worth Knowing About
If you’ve stumbled across the name MacCart’s swallow-wort (Cynanchum maccartii) in your native plant research, you’ve discovered one of Texas’s most elusive botanical treasures. This rare perennial herb belongs to the milkweed family and represents a fascinating piece of the Lone Star State’s natural heritage – though finding much information about it can feel like searching for a needle in a haystack.
What is MacCart’s Swallow-wort?
MacCart’s swallow-wort is a native Texas perennial that grows as a forb or herb – meaning it’s a non-woody plant that dies back to the ground each year but returns from its roots. Like other members of the milkweed family (Apocynaceae), it likely produces small, intricate flowers and may have a climbing or trailing growth habit typical of the Cynanchum genus.
This plant has had a bit of an identity crisis over the years, previously going by the scientific names Cynanchum palmeri and Metastelma palmeri. But regardless of what botanists call it, it remains one of Texas’s more mysterious native species.
Where Does It Grow?
MacCart’s swallow-wort is native to Texas, though its exact distribution within the state appears to be quite limited. This native status makes it a legitimate choice for Texas gardeners looking to support local ecosystems, but its apparent rarity raises some important considerations.
The Rarity Factor: Proceed with Caution
Here’s where things get tricky for eager native plant gardeners. MacCart’s swallow-wort appears to be extremely rare, with very limited information available about its current populations or conservation status. This scarcity means a few important things:
- Seeds or plants are likely not commercially available
- Wild collection could harm remaining populations
- Its specific growing requirements are largely unknown
- It may require specialized conditions that are difficult to replicate in gardens
Should You Try to Grow It?
While MacCart’s swallow-wort is undoubtedly a fascinating native species, its extreme rarity makes it an impractical choice for most gardeners. If you’re determined to grow it, only consider plants from verified, responsibly-managed sources that can guarantee they weren’t collected from wild populations.
Better Alternatives for Your Texas Native Garden
Instead of hunting for this botanical unicorn, consider these more readily available Texas native milkweed family members that offer similar ecological benefits:
- Antelope horns (Asclepias asperula) – A stunning white-flowered milkweed perfect for dry conditions
- Green milkweed (Asclepias viridis) – Unusual green flowers and excellent monarch butterfly support
- Butterfly weed (Asclepias tuberosa) – Brilliant orange flowers that pollinators absolutely love
- Zizotes milkweed (Asclepias oenotheroides) – A white-flowered Texas native that’s drought-tolerant
The Bigger Picture
MacCart’s swallow-wort serves as a reminder that Texas’s native plant diversity includes many species we’re still learning about – and some we might be in danger of losing. While you probably won’t be planting this particular species in your garden anytime soon, its existence highlights the importance of supporting native plant conservation and choosing well-established native alternatives that provide similar ecological benefits.
Sometimes the best way to honor a rare native plant is to create habitat for its more common relatives, building the kind of diverse, resilient native plant communities that support the full spectrum of Texas wildlife – including the pollinators that plants like MacCart’s swallow-wort depend on for survival.
