When does bearded swallow-wort bloom in Texas?

Most often in March. Across 356 dated, research-grade observations of Metastelma barbigerum in Texas, the flowering season runs roughly March to November.

Peak March In flower 356 Examined 372 State Texas

Flowering 356 in flower of 372 examined

Proportion of examined Metastelma barbigerum in Texas in flower, by month
Month In flower Examined Share 95% interval
Jan 3 5 60% 23% to 88%
Feb 1 1 too few examined
Mar 15 15 100% 80% to 100%
Apr 73 75 97% 91% to 99%
May 69 69 100% 95% to 100%
Jun 60 60 100% 94% to 100%
Jul 43 44 98% 88% to 100%
Aug 17 19 89% 69% to 97%
Sep 51 51 100% 93% to 100%
Oct 19 25 76% 57% to 89%
Nov 5 5 100% 57% to 100%
Dec 0 3 too few examined

Peak flowering in Mar. Each bar is the share of Metastelma barbigerum in Texas 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. 356 of 372 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.wt38fd.

What this is, and what it is not

This is a record of when people in Texas found Metastelma barbigerum in flower, not a forecast. It is computed only from observations made in Texas, so it is not the species’ global average dragged onto a map: the same plant flowers on different dates in different places, and that is the entire point of the page.

It will not tell you what your particular plant will do this year. Bloom time moves with the season, with altitude, and with the weather, and a warm February pulls everything forward. We publish the distribution and the sample size, and we refuse to draw a month that too few people examined.

The plant

Sourcesevery claim on this page

  1. GBIF (iNaturalist Research-grade Observations). Dated flowering annotations in Texas. Every record achieved iNaturalist quality grade Research, which is applied upstream at export. 10.15468/dl.wt38fd. Retrieved 2026-07-14.
  2. World Flora Online Plant List. The accepted name. CC0. Retrieved 2026-07-12.