Funastrum angustifolium(Pers.) Liede & Meve

gulf coast swallow-wort

WFO wfo-0000693490 Accepted WFO 2026-06 8 photographs CC BY

Plate 1 figs. a–h · 8 separate observations

Funastrum angustifolium, photographed by Leila Dasher
fig. a Leila Dasher, CC BY 4.0 / 2022-05-16 / obs. 198875904

Every figure is a research-grade observation under CC0, CC BY or CC BY-SA, rehosted with the photographer’s name, the licence and the observation it came from. Photographs under a NonCommercial licence are excluded from this site and are never stored, which costs us a great many pictures and is not negotiable.

Native range 19 botanical countries

Regions where Funastrum angustifolium is native: Alabama, Florida, Georgia, Louisiana, Mexico Central, Mexico Gulf, Mexico Northeast, Mexico Northwest, Mexico Southeast, Mexico Southwest, Mississippi, North Carolina, South Carolina, Texas, Bahamas, Belize, Cayman Is., Cuba, Turks-Caicos Is. AlabamaFloridaGeorgiaLouisianaMexico CentralMexico GulfMexico NortheastMexico NorthwestMexico SoutheastMexico SouthwestMississippiNorth CarolinaSouth CarolinaTexasBelizeCuba BahamasCayman Is.Turks-Caicos Is.
Native distribution of Funastrum angustifolium, after Kew’s World Checklist of Vascular Plants. Introduced, extinct and doubtful records are excluded, so this is where the plant is from, not everywhere it now grows. Regions too small to draw at this scale are marked with a dot.
RegionTDWG codeContinent
Alabama ALA NORTHERN AMERICA
Florida FLA
Georgia GEO
Louisiana LOU
Mexico Central MXC
Mexico Gulf MXG
Mexico Northeast MXE
Mexico Northwest MXN
Mexico Southeast MXT
Mexico Southwest MXS
Mississippi MSI
North Carolina NCA
South Carolina SCA
Texas TEX
Bahamas BAH SOUTHERN AMERICA
Belize BLZ
Cayman Is. CAY
Cuba CUB
Turks-Caicos Is. TCI

Region boundaries approximated from Natural Earth (public domain) and mapped to TDWG World Geographical Scheme for Recording Plant Distributions (WGSRPD) level-3 botanical countries (Brummitt 2001). Indicative, not the official WGSRPD geometry.

Flowering 260 in flower of 294 examined

Proportion of examined Funastrum angustifolium in flower, by month
Month In flower Examined Share 95% interval
Jan 0 1 too few examined
Feb 0 0 too few examined
Mar 1 3 too few examined
Apr 18 20 90% 70% to 97%
May 61 62 98% 91% to 100%
Jun 65 67 97% 90% to 99%
Jul 50 54 93% 82% to 97%
Aug 30 35 86% 71% to 94%
Sep 22 26 85% 66% to 94%
Oct 12 19 63% 41% to 81%
Nov 1 6 17% 3% to 56%
Dec 0 1 too few examined

Peak flowering in May. Each bar is the share of Funastrum angustifolium observations in which someone actually recorded the reproductive state and found the plant in flower, not the raw number of flowering records. That distinction matters: people observe plants far more in spring than in winter, so a bare count of flowering records partly measures when people go outside. Dividing by the number examined removes that. 260 of 294 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 4 months have fewer than 5 examined observations, so no proportion is drawn for them. This is still a global aggregate and not a forecast for your garden: the same species flowers on different dates in different hemispheres. Where a species has fewer than 30 flowering records we do not draw this chart at all. Computed from 10.15468/dl.cgje2x.

Where it actually grows measured, from 814 observations

Condition 5th percentile Median 95th percentile
Coldest month, mean daily low 7.2 °C 11.2 °C 19.9 °C
Warmest month, mean daily high 27.3 °C 29.7 °C 31.1 °C
Annual rainfall 885 mm 1,365 mm 1,620 mm
Rainfall in the driest quarter 131 mm 227 mm 331 mm

It is barely found anywhere that freezes. This is not care advice and it is not a forecast. It is a measurement: we sampled the climate at every one of the 814 research-grade observations of Funastrum angustifolium that carry a coordinate, and this is the range those places actually span. The 5th and 95th percentiles are used rather than the minimum and maximum, because a single cultivated specimen in a heated conservatory should not widen a tropical plant's range to the Arctic.

This is not a hardiness zone. A USDA zone is the average annual extreme minimum temperature. The figure above is the mean daily minimum of the coldest month, which is a different quantity and is typically far warmer. Reading one as the other would place a plant several zones too warm, so we do not publish a hardiness zone, because we do not have one. Climate from CHELSA V2.1 (Karger et al. 2017); occurrences from 10.15468/dl.cgje2x.

Also published as 14 synonyms

A synonym is not an error. It is a record of botanists disagreeing, in print, about where this plant belongs. Each of these was somebody’s considered answer.

  • Amphistelma salinarum C.Wright ex Griseb.
  • Ceropegia palustris Pursh
  • Cynanchum angustifolium Pers.
  • Cynanchum palustre (Pursh) A.Heller
  • Cynanchum salinarum (C.Wright ex Griseb.) Alain
  • Cynoctonum angustifolium (Pers.) Small
  • Lyonia palustris (Pursh) Small
  • Metastelma palustre (Pursh) Schltr.
  • Metastelma salinarum (C.Wright ex Griseb.) C.Wright
  • Pattalias palustris (Pursh) Fishbein
  • Seutera angustifolia (Pers.) Fishbein & W.D.Stevens
  • Seutera maritima Decne.
  • Seutera palustris (Pursh) Vail
  • Vincetoxicum palustre (Pursh) A.Gray

Sourcesevery claim on this page

  1. World Flora Online Plant List. accepted name, authority, classification. CC0. Retrieved 2026-07-12.
  2. iNaturalist. photographs and flowering annotations, CC0 / CC BY / CC BY-SA only. per photograph. Retrieved 2026-06-27.
  3. USDA PLANTS Database. common name, checklist symbol CYAN5. public domain. Retrieved 2026-07-13.
  4. Kew, World Checklist of Vascular Plants (WCVP v16). native distribution by TDWG level-3 botanical country, and life form. CC BY 3.0. Retrieved 2026-06-04.

We publish what we can source and we say so when we cannot. This page has no care advice and no toxicity claim, because we do not yet have those from a source we can cite.