Metastelma barbigerumScheele

bearded swallow-wort

WFO wfo-0001102222 Accepted WFO 2026-06 8 photographs CC BY

Plate 1 figs. a–h · 8 separate observations

Metastelma barbigerum, photographed by Michelle W. (鍾偉瑋)
fig. a Michelle W. (鍾偉瑋), CC BY 4.0 / 2021-10-11 / obs. 163016644

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 5 botanical countries

Regions where Metastelma barbigerum is native: Mexico Gulf, Mexico Northeast, Mexico Southeast, Mexico Southwest, Texas Mexico GulfMexico NortheastMexico SoutheastMexico SouthwestTexas
Native distribution of Metastelma barbigerum, 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.
RegionTDWG codeContinent
Mexico Gulf MXG NORTHERN AMERICA
Mexico Northeast MXE
Mexico Southeast MXT
Mexico Southwest MXS
Texas TEX

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 390 in flower of 415 examined

Proportion of examined Metastelma barbigerum in flower, by month
Month In flower Examined Share 95% interval
Jan 3 6 50% 19% to 81%
Feb 1 1 too few examined
Mar 19 19 100% 83% to 100%
Apr 78 81 96% 90% to 99%
May 72 74 97% 91% to 99%
Jun 63 63 100% 94% to 100%
Jul 50 51 98% 90% to 100%
Aug 18 21 86% 65% to 95%
Sep 56 57 98% 91% to 100%
Oct 22 28 79% 60% to 90%
Nov 8 11 73% 43% to 90%
Dec 0 3 too few examined

Peak flowering in Mar. Each bar is the share of Metastelma barbigerum 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. 390 of 415 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 2 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 1,391 observations

Condition 5th percentile Median 95th percentile
Coldest month, mean daily low 5.4 °C 6.5 °C 12.5 °C
Warmest month, mean daily high 32.3 °C 34.2 °C 35.9 °C
Annual rainfall 587 mm 874 mm 966 mm
Rainfall in the driest quarter 78 mm 155 mm 183 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 1,391 research-grade observations of Metastelma barbigerum 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 1 synonym

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.

  • Cynanchum barbigerum (Scheele) Shinners

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 CYBA. 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.