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Back to: Plants at Risk in Saskatchewan
Epilobium pygmaeum (Speg.) Hoch & Raven
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TAXONOMY
 
Family: Onagraceae
Genus: Epilobium
 
Species Synonyms: Boisduvalia glabella (Nutt.) Walt.
Boisduvalia glabella var. campestris (Jepson) Jepson
Boisduvalia pygmaea (Speg.) Munz
Oenothera glabella Nutt.
Common Names: smooth willoweed
smooth boisduvalia
smooth spike-primrose
 
DISTRIBUTION
 
Canada: south-central British Columbia, southeastern Alberta – south-central Saskatchewan
Saskatchewan: southwestern – south-central Saskatchewan; Leader – Cypress Hills – Val Marie, Wood Mountain – Mortlach
Ecoregion: Cypress Upland, Mixed Grassland, Moist Mixed Grassland
 
HABITAT
 
Saskatchewan: moist to drying, bare, clayey mud flats in prairie and field depressions, slough bottoms, and shores
 
RARITY STATUS
 
Provincial Status According
to Harms (2003):
Vulnerable
Nature Conservancy Status:
G5 N2 S2
Saskatchewan Species at
Risk Status:
None
COSEWIC Status:
None
 
Epilobium pygmaeum is vulnerable because it is rare or uncommon in Saskatchewan. It is only somewhat regionally restricted extending to a limited extent into adjacent general regions of the province. Most local populations are small. Possible threats have been identified for this species.
 
SPECIES DESCRIPTION
 
Height: 10 – 30 cm
Roots: taproot
Stems: annual, decumbent and spreading, often branching near the base, glabrous to pubescent
Leaves: alternate, sessile, 10 – 20 mm long, lanceolate to ovate, margin dentate to entire
Inflorescence: spikes leafy, terminal, flowers crowded
Flowers: inconspicuous; calyx 4-merous, green; corolla 4-merous, < 3 mm long, purple or violet; pollen in tetrads; stigma capitate
Fruits: capsule 6 – 8 mm long, 4-ribbed, pointed but not beaked; seeds many
 
EPILOBIUM KEY FOR SPECIES FOUND IN SASKATCHEWAN
 
1 Seeds without a coma; leaves always alternate; plants annual, in seasonally moist areas which are dry at time of flowering
E. pygmaeum
1 Seeds comose; leaves alternate or opposite; plants annual or perennial, in permanently moist areas which are moist at time of flowering
2
   
2 Plants annual, with a taproot; epidermis on lower stem exfoliating; comas pale yellow, deciduous
E. brachycarpum
2 Plants perennial, often with turions or stolons; epidermis not exfoliating; comas whitish, persistent
3
   
3 Plants with thread-like, somewhat leafy stolons with turions; inflorescence white hairy; cauline leaves often revolute
4
3 Plants without stolons; inflorescences glandular-pubescent or glabrous; cauline leaves never revolute
5
   
4 Leaves linear to lanceolate; inflorescence without glands; flowers nodding in bud
E. palustre
4 Leaves linear; inflorescence with glandular and other hairs; flowers erect
E. leptophyllum
   
5 Plants to 60 cm high, not forming rosettes
E. halleanum
5 Plants to 190 cm high, forming rosettes
6
   
6 Cauline leaves narrowly lanceolate to ovate; inflorescence not leafy, branched; corolla white to pink
E. ciliatum ssp. ciliatum
6 Cauline leaves broader; inflorescence leafy, unbranched; corolla pink to purple
E. ciliatum spp. glandulosum