Photo: Wolffia columbiana on left, Wolffia brasiliensis on right (W. columbinana left, W. brasiliensis right)

Wolffia brasiliensis Weddell

Pointed Watermeal

Habitat: Mesotrophic to eutrophic waters of lakes, rivers, and backwaters. [Open water (non-forested, wetland)]

Range: Maine, Connecticut and Massachusetts south to Virginia, west to Kansas.

Aids to Identification: This tiny aquatic plant is one of the smallest flowering plants. It is found floating low in the water with a small portion in contact with the air. The thalli (undifferentiated plant tissues) are ovoid and slightly asymmetrical (mostly 0.5-1.5 mm x 0.3-1.0 mm) with no veins or roots. Wolffia brasiliensis is similar in appearance to W. columbiana. Post-mortem, W. brasiliensis is punctate (dotted) with brown pigment-cells.

Photo: Wolffia columbiana on left, Wolffia brasiliensis on right (W. columbinana left, W. brasiliensis right)

Ecological characteristics: Wolffia species often grow in association with Lemna species (duckweed).

Phenology: Reproduces by vegetative budding. Flowers are rarely produced.

Family: Araceae

Synonyms: Bruniera punctata (Griseb.) Nieuwl.; Wolffia papulifera C.H. Thompson; Wolffia punctata Griseb.

Known Distribution in Maine: This rare plant has been documented from a total of 1 town(s) in the following county(ies): York.

Reason(s) for rarity: At northern limit of range.

Conservation considerations: None noted.