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Asclepiadaceae family

Gulf Coast Swallow-wort Cynanchum angustifolium

Native ★ Monarch host plant

Gulf Coast Swallow-wort is a perennial vine native to the lower 48 states. It blooms May – Aug. Monarch host plant.

More about this plant

Funastrum angustifolium is a plant species. Commonly known as the Gulf coast swallow-wort, it is a perennial dicot that grows in the southern United States as far west as Texas. It is in the Cynanchum genus and Apocynaceae family. A flowering vine, it produces white blossoms with greenish and yellow parts. A member of the milkweed family, it is a plant host for monarch butterflies and produces wind dispersed seed pods. Wikipedia →

Growing & care

USDA PLANTS · TRY
Conditions
Sources · Conditions
Cold hardiness (derived) — Hardiness
Hardiness
≥ zone 9 derived from its U.S. range
Size & form
Sources · Size & form
USDA PLANTS — Lifespan
Lifespan
Perennial
In the garden
Vine / climber layer — Sits in the vine of a layered food forest or polyculture.Open guide →
derived roles
The garden year bloom → fruit → fall colour
J
F
M
A
M
J
J
A
S
O
N
D
Bloom
Bloom (the flower's colour)
Bloom · May – Aug — 12 obs · Herbarium specimens — Park et al. 2023 (CC BY 4.0)
Species characteristics from USDA PLANTS (public domain) + TRY (CC BY) — general guidance, not a guarantee for your exact site. Deer "browsing" is documented palatability, not a deer-proof claim.

Wildlife & pollinators

How pollinator value is scored →
★ Monarch Secondary host

A secondary monarch host.

Monarchs will use Gulf Coast Swallow-wort as a host where primary milkweeds are scarce.

Find milkweed near you Journey North migration map →
Host status from PlantKey's open monarch-host overlay · migration data via Journey North (link)
❧ 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:

Danaus gilippus · Queen ✦ Danaus plexippus · Monarch ✦ Erinnyis obscura · Obscure Sphinx ✦ Eucereon carolina · tiger moth ✦ Eucereon confine · tiger moth ✦ Glyphodes floridalis · snout moth ✦
+ 3 more species →
Composia fidelissima · Faithful Beauty Danaus eresimus · Soldier Euchaetes egle · Milkweed Tussock Moth
Keystone count (genus-level) from Warren II 2026 (CC0) · Tallamy host-use records. Named species (a documented Nearctic sample, not exhaustive) from NHM HOSTS (CC0). ✦ = recorded on this exact species.
Species thumbnails re-hosted from iNaturalist — Creative Commons, credited per image (hover for credit). Click any species to see it on iNaturalist. Not exhaustive; many taxa have no openly-licensed photo yet.
Sources for this entry (12) Open & cited
[01] Scientific name & family — USDA PLANTS (DwCA, Zenodo 17903503)
[02] Growth habit & duration — USDA PLANTS (DwCA, Zenodo 17903503)
[03] Native status & distribution — USDA PLANTS (DwCA, Zenodo 17903503)
[04] Common name — USDA PLANTS (via GBIF)
[05] Invasive / introduced status — USDA PLANTS (DwCA, Zenodo 17903503) — native status
[06] Description — Wikipedia (CC BY-SA)
[07] Ecological value — Warren II 2026 (CC0) · Tallamy host-use counts · Asclepias host rule
[09] Conservation rank — NatureServe Explorer (CC BY)
[10] Cold hardiness (derived) — Derived from U.S. range × USDA PHZM zones
[11] Caterpillar host count — Warren II 2026 (Dryad, CC0) · Tallamy host-use counts
[12] Caterpillar species — NHM HOSTS (CC0)
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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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