BC Conservation Data Centre: Species Summary
Isoetes occidentalis
western quillwort
| Scientific Name: | Isoetes occidentalis Henderson | ||||||||||
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| Scientific Name Synonyms: |
Isoetes flettii
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| English Name: | western quillwort | ||||||||||
| Classification / Taxonomy | |||||||||||
| Scientific Name - Concept Reference: | Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR. | ||||||||||
| Classification Level: | Species | ||||||||||
| Species Group: | Vascular Plant | ||||||||||
| Species Code: | ISOEOCC | ||||||||||
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| Conservation Status / Legal Designation | |||||||||||
| Global Status: | G4G5 (Nov 2011) | ||||||||||
| Provincial Status: | S5 (Apr 2019) | ||||||||||
| BC List: | Yellow | ||||||||||
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| Provincial Wildlife Act: | |||||||||||
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| SARA Schedule: | |||||||||||
| General Status Canada: | 4 - Secure (2010) | ||||||||||
| Ecology & Life History | |||||||||||
| General Description: | |||||||||||
| Technical Description: | From CNHP Wetland Guide 2012: Growth Habit: aquatic, occasionally emergent. Rootstock: nearly globose, 2-lobed. Leaves: evergreen, dark green, pale toward base, spirally arranged to 20 cm, rigid, gradually tapering to tip. Velum (membrane covering sporangium): covering less than ½ of sporangium Sporangium wall: unpigmented. Megaspores: 500-700 microns diameter, cristate, tuberculate, regulate, or echinate with ridges, tubercles, or spines; girdle smooth. Microspores: brown in mass, 35-45 microns, bearing bumps (papillose) to spines (spinulose). Spores mature in late summer. |
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| Diagnostic Characteristics: | From CNHP Wetland Guide 2012: Main Characteristics: Leaves strictly erect, stiff, gradually tapering to tip Megaspores mostly 0.5-0.7 mm wide with high ridges or jagged crests Sporangium wall is not pigmented |
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| Similar Species: | |||||||||||
| Global Ecology Comments: | From CNHP Wetland Guide 2012: Comments: Quillworts are intolerant of nutrient enrichment and can be an indicator of good water quality (Washington State Dept. of Ecology 2011). Plants are often washed ashore by wave action (Weber and Wittman 2012) | ||||||||||
| Habitats: (Type / Subtype / Dependence) |
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| Global Habitat Comments: | Submersed in mountain lakes. Red fir to subalpine forest, 6000-11000 feet. | ||||||||||
| Provincial Phenology: (1st half of month/ 2nd half of month) |
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| Elevation (m) (min / max): | Provincial: | ||||||||||
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| Distribution | |||||||||||
| Endemic: | N | ||||||||||
| Global Range Comment: | Alaska, British Columbia, and California, east to Montana, Wyoming and Colorado. |
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| Disjunct, more common elsewhere: | |||||||||||
| Peripheral, major distribution elsewhere: | |||||||||||
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| Last Literature Search: | |||||||||||
| References and Related Literature | |||||||||||
Flora of North America Editorial Committee (FNA). 1993a. Flora of North America north of Mexico. Vol. 2. Pteridophytes and gymnosperms. Oxford Univ. Press, New York. xvi + 475 pp. |
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Please visit the website Conservation Status Ranks for definitions of the data fields used in this summary report.
Suggested Citation:
B.C. Conservation Data Centre. Species Summary: Isoetes occidentalis. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jun 7, 2026).