Honeyvine Cynanchum laeve
Honeyvine is a perennial vine native to the lower 48 states. It blooms Jul – Aug. Monarch host plant.
More about this plant
Cynanchum laeve is a vining perennial herb native to eastern and central U.S. states and Ontario. Common names include sand vine, honeyvine, honeyvine milkweed, bluevine milkweed, climbing milkweed, and smooth swallow-wort. The root system of C. laeve can cause it to be very difficult to eradicate, especially in agricultural fields. It is a larval food of monarch butterflies and milkweed tussock moth larvae. C. laeve can cause eye irritation if touched and can be toxic to humans and livestock if consumed in large quantities. Wikipedia →
Growing & care
USDA PLANTS · TRY- Hardiness
- ≥ zone 6 derived from its U.S. range
- Lifespan
- Perennial
- Flower colour
- Green AI AI image-analysis of community-science photos (~87% expert agreement) — not a botanical record
Wildlife & pollinators
How pollinator value is scored →★ Monarch Secondary host
A secondary monarch host.
Monarchs will use Honeyvine as a host where primary milkweeds are scarce.
❧ Caterpillar hosts ~3 caterpillar species
Cynanchum supports ~3 caterpillar species.
Native butterfly & moth caterpillars are the base of the terrestrial food web — most songbirds rear their young almost entirely on them. As a host for native Lepidoptera this is a modest genus.
Recorded feeding on Cynanchum in North America, including:
+ 3 more species → ↑ show fewer
✦ Bees 20 bee visitors
20 native & managed bee species are documented visiting Honeyvine — the 12 most-recorded:
Wildlife & visitors 17 nectaring
Open records of who else uses Honeyvine — a generalist food-web signal, kept separate from the keystone Ecological Value.
17 adult butterfly & moth species are recorded nectaring at its flowers — the most-recorded:
How we know this (2) Methods & honest limits
We take the plant’s U.S. county range and look up each county’s long-term climate, then summarise: native rainfall = the median annual rainfall across its counties; heat tolerance = the warm end (90th percentile) of average temperature across its range (mirroring how our cold-hardiness floor uses an extreme). Counties + medians blunt the roadside/observer bias that makes point-level climate unreliable. Needs at least five placeable counties.
Honest limits: A realized, sampling-biased niche (where it has been recorded, not its physiological optimum), and county climate is coarse — large Western counties span deserts and mountains. Derived guide, never a measured fact.
McKenzie et al. assigned each species a flower colour with a GPT-4V vision model over iNaturalist photos. We use the confident tier plus a separately-labelled lower-confidence top-up (mostly inconspicuous green/brown flowers), and render it as a small tint — never as an asserted fact, and kept out of the written synopsis.
Honest limits: AI image inference (~87% expert agreement on the confident tier); a decorative, confidence-tiered indicator, not a measured trait.
Sources for this entry (21) Open & cited
Cite this page Open data, please attribute
PlantKey’s data is open under CC BY-SA 4.0 — free to reuse and adapt, with attribution and the same licence. Photos keep their own per-image licence + credit (see Sources above).
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