North America Native Plant

Fragrant Swallow-wort

Botanical name: Cynanchum northropiae

USDA symbol: CYNO

Life cycle: perennial

Habit: vine

Native status: Native to the lower 48 states  

Synonyms: Epicion northropiae (Schltr.) Small (EPNO3)   

Fragrant Swallow-Wort: A Rare Florida Native Worth Knowing Meet the fragrant swallow-wort (Cynanchum northropiae), a lesser-known gem hiding in Florida’s native plant community. This perennial herb might not be gracing garden center shelves anytime soon, but it’s definitely worth understanding – especially if you’re passionate about conserving Florida’s unique botanical ...

Rare plant alert!

Region: Conservation status by state

Status: S3S4: Status is uncertain but is somewhere between the following rankings: Vulnerable: Either very rare and local throughout its range, found only in a restricted range (even if abundant at some locations), or factors are making it vulnerable to extinction. Typically 21 to 100 occurrences or between 3,000 and 10,000 individuals ⚘ Apparently Secure: Uncommon but not rare, and usually widespread. Possibly cause for longterm concern. Typically more than 100 occurrences in the state or more than 10,000 individuals ⚘

Fragrant Swallow-Wort: A Rare Florida Native Worth Knowing

Meet the fragrant swallow-wort (Cynanchum northropiae), a lesser-known gem hiding in Florida’s native plant community. This perennial herb might not be gracing garden center shelves anytime soon, but it’s definitely worth understanding – especially if you’re passionate about conserving Florida’s unique botanical heritage.

What Makes This Plant Special?

Fragrant swallow-wort belongs to the milkweed family (Apocynaceae), which immediately tells us something interesting about its potential garden value. As a native Florida perennial herb, it’s adapted to thrive in the Sunshine State’s unique climate and growing conditions. The plant grows as what botanists call a forb – essentially a non-woody plant that dies back to ground level but returns year after year from its root system.

Where You’ll Find It (And Where You Won’t)

This plant calls Florida home and apparently nowhere else in the United States. It’s what we call an endemic species – a plant that evolved in one specific region and never spread beyond those boundaries naturally.

The Conservation Reality Check

Here’s where things get serious: fragrant swallow-wort has a conservation status of S3S4, which means it’s considered uncommon to apparently secure within its range. In plain English? This plant is rare enough that we need to be thoughtful about how we interact with it.

Important note for gardeners: If you’re interested in growing this species, please only source plants from reputable native plant nurseries that propagate their stock responsibly. Never collect from wild populations.

Potential Garden Benefits

While detailed horticultural information about fragrant swallow-wort is limited, its family connections give us some clues about its potential benefits:

  • As a member of the milkweed family, it likely attracts pollinators, particularly native bees and butterflies
  • Being a Florida native, it’s naturally adapted to local climate conditions
  • Perennial growth habit means it returns year after year once established
  • Low-maintenance requirements typical of well-adapted native species

Growing Conditions and Care

Since fragrant swallow-wort is native to Florida, we can make some educated guesses about its preferred growing conditions:

  • Hardiness zones: Likely thrives in USDA zones 9-11
  • Climate needs: Adapted to Florida’s humid subtropical climate
  • Maintenance: Probably low-maintenance once established, like most native plants

Should You Grow It?

The honest answer is: it depends. If you’re a Florida gardener passionate about native plants and conservation, and you can source plants responsibly, fragrant swallow-wort could be a meaningful addition to a native plant garden. However, due to its rarity, it’s not a plant for casual gardening.

For most Florida gardeners interested in native milkweed family plants, consider these more readily available alternatives:

  • White milkweed (Asclepias perennis)
  • Butterfly weed (Asclepias tuberosa)
  • Swamp milkweed (Asclepias incarnata)

The Bottom Line

Fragrant swallow-wort represents the fascinating diversity of Florida’s native flora. While it may not be the easiest plant to find or grow, knowing about species like this helps us appreciate the complexity and beauty of our local ecosystems. If you encounter this plant in the wild, take a moment to appreciate its rarity – you’re looking at a true Florida original.

For most gardeners, supporting conservation efforts and choosing more common native alternatives will have a bigger positive impact. But for dedicated native plant enthusiasts with access to responsibly sourced material, fragrant swallow-wort offers a chance to cultivate something truly special.

Fragrant Swallow-wort

Classification

Group

Dicot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Magnoliopsida - Dicotyledons

Subclass

Asteridae

Order

Gentianales

Family

Asclepiadaceae Borkh. - Milkweed family

Genus

Cynanchum L. - swallow-wort

Species

Cynanchum northropiae (Schltr.) Alain - fragrant swallow-wort

Plant data source: USDA, NRCS 2025. The PLANTS Database. https://plants.usda.gov,. 2/25/2025. National Plant Data Team, Greensboro, NC USA