Giliastrum incisum(Benth.) J.M.Porter

splitleaf gilia

WFO wfo-0000703204 Accepted WFO 2026-06 8 photographs CC BY / CC BY-SA

Plate 1 figs. a–h · 8 separate observations

Giliastrum incisum, photographed by Leticia Jiménez Hernández
fig. a Leticia Jiménez Hernández, CC BY-SA 4.0 / 2020-08-25 / obs. 92230539

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 Giliastrum incisum is native: Mexico Gulf, Mexico Northeast, New Mexico, Texas, Dominican Republic Mexico GulfMexico NortheastNew MexicoTexasDominican Republic
Native distribution of Giliastrum incisum, 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
New Mexico NWM
Texas TEX
Dominican Republic DOM SOUTHERN AMERICA

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 179 in flower of 204 examined

Proportion of examined Giliastrum incisum in flower, by month
Month In flower Examined Share 95% interval
Jan 2 2 too few examined
Feb 12 15 80% 55% to 93%
Mar 39 43 91% 78% to 96%
Apr 59 66 89% 80% to 95%
May 22 24 92% 74% to 98%
Jun 14 15 93% 70% to 99%
Jul 8 8 100% 68% to 100%
Aug 2 3 too few examined
Sep 8 8 100% 68% to 100%
Oct 7 12 58% 32% to 81%
Nov 4 5 80% 38% to 96%
Dec 2 3 too few examined

Peak flowering in Jul. Each bar is the share of Giliastrum incisum 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. 179 of 204 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 3 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 786 observations

Condition 5th percentile Median 95th percentile
Coldest month, mean daily low 5.0 °C 6.3 °C 11.7 °C
Warmest month, mean daily high 28.6 °C 34.0 °C 35.4 °C
Annual rainfall 507 mm 849 mm 967 mm
Rainfall in the driest quarter 54 mm 152 mm 184 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 786 research-grade observations of Giliastrum incisum 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 5 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.

  • Gilia incisa Benth.
  • Gilia lindheimeriana Scheele
  • Gilia perennans Shinners
  • Navarretia incisa (Benth.) Kuntze
  • Polemonium incisum Kuntze

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. Wikidata. common name (P1843), joined on the World Flora Online identifier (P7715). CC0. 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.