Myriophyllum quitenseKunth

Andean watermilfoil

WFO wfo-0000373487 Accepted WFO 2026-06 8 photographs CC BY

Plate 1 figs. a–h · 8 separate observations

Myriophyllum quitense, photographed by Humber Alberto
fig. a Humber Alberto, CC BY 4.0 / 2022-05-02 / obs. 194697081

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 29 botanical countries

Regions where Myriophyllum quitense is native: Falkland Is., Chatham Is., New Zealand North, New Zealand South, Arizona, British Columbia, California, Idaho, Mexico Central, Montana, New Brunswick, Oregon, Prince Edward I., Utah, Washington, Wyoming, Argentina Northeast, Argentina Northwest, Argentina South, Bolivia, Brazil South, Chile Central, Chile North, Chile South, Colombia, Ecuador, Peru, Uruguay, Venezuela Falkland Is.New Zealand NorthNew Zealand SouthArizonaBritish ColumbiaCaliforniaIdahoMexico CentralMontanaNew BrunswickOregonPrince Edward I.UtahWashingtonWyomingArgentina NortheastArgentina NorthwestArgentina SouthBoliviaBrazil SouthChile CentralChile NorthChile SouthColombiaEcuadorPeruUruguayVenezuela Chatham Is.
Native distribution of Myriophyllum quitense, 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
Argentina Northeast AGE SOUTHERN AMERICA
Argentina Northwest AGW
Argentina South AGS
Bolivia BOL
Brazil South BZS
Chile Central CLC
Chile North CLN
Chile South CLS
Colombia CLM
Ecuador ECU
Peru PER
Uruguay URU
Venezuela VEN
Arizona ARI NORTHERN AMERICA
British Columbia BRC
California CAL
Idaho IDA
Mexico Central MXC
Montana MNT
New Brunswick NBR
Oregon ORE
Prince Edward I. PEI
Utah UTA
Washington WAS
Wyoming WYO
Chatham Is. CTM AUSTRALASIA
New Zealand North NZN
New Zealand South NZS
Falkland Is. FAL ANTARCTICA

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 41 in flower of 54 examined

Proportion of examined Myriophyllum quitense in flower, by month
Month In flower Examined Share 95% interval
Jan 13 14 93% 69% to 99%
Feb 6 9 67% 35% to 88%
Mar 10 12 83% 55% to 95%
Apr 0 1 too few examined
May 0 1 too few examined
Jun 0 0 too few examined
Jul 0 0 too few examined
Aug 0 0 too few examined
Sep 1 1 too few examined
Oct 2 3 too few examined
Nov 7 9 78% 45% to 94%
Dec 2 4 too few examined

Peak flowering in Jan. Each bar is the share of Myriophyllum quitense 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. 41 of 54 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 8 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 167 observations

Condition 5th percentile Median 95th percentile
Coldest month, mean daily low -6.9 °C -0.9 °C 6.9 °C
Warmest month, mean daily high 10.3 °C 14.3 °C 26.0 °C
Annual rainfall 301 mm 1,166 mm 2,261 mm
Rainfall in the driest quarter 12 mm 118 mm 339 mm

It is found where winters bring hard frost. This is not care advice and it is not a forecast. It is a measurement: we sampled the climate at every one of the 167 research-grade observations of Myriophyllum quitense 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 8 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.

  • Myriophyllum elatinoides Gaudich.
  • Myriophyllum elatinoides var. ternatum Reiche
  • Myriophyllum pallidum Rusby
  • Myriophyllum propinquum A.Cunn.
  • Myriophyllum ternatum Gaudich.
  • Myriophyllum ternatum var. tetraphyllum Hook. & Arn.
  • Myriophyllum titikakense J.Rémy
  • Myriophyllum viridescens Gillies ex Hook. & Arn.

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.