E-Flora BC: Electronic Atlas of the Flora of British Columbia

Callitriche heterophylla Pursh subsp. heterophylla
two-edged water-starwort (twoheaded water-starwort)
Plantaginaceae (Mare's-tail family)
(Previously in Callitrichaceae)

Introduction to Vascular Plants
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E-Flora BC Static Map
Distribution of Callitriche heterophylla subsp. heterophylla
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This aquatic to semi-aquatic perennial subspecies is widespread across North America (USDA 2011) and is found across British Columbia.

In his article on rare plants of the Fraser Valley, Lomer (2011) says: "This species as a whole is common, but the variety heterophylla is not often collected in BC. [In the Fraser Valley], records exist from the Vancouver area, including Coquitlam (UBC: Lomer 90-7), Surrey (UBC: Lomer 91-125A) and Pitt Lake (V: Brayshaw 78-794B) so it should be expected in more wetland sites in the Fraser Valley. The small fruit, less than 1 mm, mark the variety. So it is not surprising there are few records". Extracted from Botanical Electronic News #432, January 2011, with permission.

Species Information

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Aquatic or semi-aquatic perennial rooting in mud; stems leafy, 2-40 cm long, with or without small membranous ridges between the leaf-bases.
All opposite; submerged leaves linear, single-veined, notched at the tip, 5-25 mm long; floating and emergent leaves broadly egg-shaped or oblanceolate, 3-veined, up to 1 cm wide.
Inflorescence of tiny, inconspicuous flowers borne with a pair of tiny bracts, stalkless or shortly-stalked; styles 1-5 mm long, ascending.
Achene-like, 4, each 1-seeded, wingless or scarcely wing-margined, rounded, egg-shaped or heart-shaped, irregularly pitted.
Two subspecies occur in our region.

1. Fruits egg-shaped or slightly heart-shaped in outline, broadest above the middle; submersed leaves usually wider than the stem; plants long-stemmed........................ ssp. bolanderi (Hegelm.) Calder & Tayl.

1. Fruits usually more nearly round or egg-shaped in outline; submersed leaves much narrower than the flattened stem; plants short-stemmed....................... ssp. heterophylla

Source: The Illustrated Flora of British Columbia

Habitat / Range

Shallow ponds, slow-moving streams and shorelines in the lowland and montane zones; ssp. bolanderi- frequent on S Vancouver Island, rare in SE BC, ssp. heterophylla - rare in coastal BC; N to AK, YT, NT, E to NF and S to GA, TX, OK and CA; South America (ssp. bolanderi).

Source: The Illustrated Flora of British Columbia


The climate type for this species, as reported in the: "British Columbia plant species codes and selected attributes. Version 6 Database" (Meidinger et al. 2008), is not evaluated, unknown or variable.

Synonyms and Alternate Names

Callitriche anceps Fernald

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