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

Crassula aquatica (L.) Schoenl.
pigmyweed (water pygmyweed)

Introduction to Vascular Plants

© Doug Murphy  Email the photographer   (Photo ID #66549)

E-Flora BC Static Map
Distribution of Crassula aquatica
Click here to view our interactive map and legend
Details about map content are available here
Click on the map dots to view record details.


Pigmyweed is circumpolar annual, succulent-leaved herb that is found in North America in western, southern and eastern US states and most Canadian provinces (USDA 2011). In British Columbia, it is found infrequently in the southern part of the province, in wet vernal pools and mudflats in the lowland zone.

In his rare plants of the Fraser Valley article, Lomer (2011) says: "A local plant of muddy sites usually along major rivers in [southern] BC such as the Columbia, Fraser, Harrison, Pitt and Pend d'Oreille. It is abundant and co-dominant in tidal mudflats along the lower Fraser from Steveston to Langley and along the Pitt River to Pitt Lake, as well as east to Harrison Lake (UBC: Straley 6267). It is widespread in southern BC from Vancouver Island to the Rocky Mt Trench. Now known from enough sites that it was recommended for removal from the BC rare plant tracking list." Extracted from Botanical Electronic News #432, January 2011, with permission.

Species Information

Click on the image below to view an expanded illustration for this species.

Weak annual herb, rooting nodally; stems ascending or erect, freely branching, 2-6 cm tall/long, glabrous.
Opposite, entire, succulent, linear to linear-oblanceolate, 3-6 mm long, with heart-shaped, sheathing bases.
Inflorescence of single flowers in the leaf axils; flowers usually 4-merous, greenish, short-stalked but lengthening in fruit; calyces cup-shaped; petals exceeding the sepals, whitish; stamens shorter than the petals.
Follicles, less than 2 mm long, purplish, 6-12 seeded.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Wet vernal pools and mudflats in the lowland zone; infrequent, scattered through S BC; circumpolar, N to AK and NT and S to CA and MX; Iceland, Eurasia.

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

Bulliarda aquatica (L.) DC.
Hydrophila aquatica (L.) House
Tillaea angustifolia Nutt.
Tillaea aquatica L.
Tillaea ascendens Eat.
Tillaeastrum aquaticum (L.) Britt.

Taxonomic and Nomenclatural Links

Additional Photo Sources

General References