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

Megalodonta beckii (Torr. ex Spreng.) Greene (Torr. ex Spreng.) Greene
water marigold
Asteraceae (Aster family)

Introduction to Vascular Plants
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Distribution of Megalodonta beckii
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Species Information

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Perennial aquatic herb from a fibrous root; stems simple or few branched above, solitary, glabrous, 0.5-2 m long.
Basal leaves lacking; lower leaves submersed, short-stalked, essentially whorled, 3-parted almost to the base, the lobes many times forked into threadlike segments, glabrous, 1.5-4 mm; upper leaves emergent, few or rarely lacking, unstalked, lanceolate to egg-shaped, glabrous, sharply toothed, 1-3.5 cm long.
Heads with ray and disk flowers, few, solitary and terminal at the ends of branches; involucres 12-20 mm tall; involucral bracts about 5-6, the outer ones egg-shaped, thickly leafy, the inner ones oblanceolate, more or less membraneous, narrowly yellow-margined; ray flowers golden yellow, usually 8, 1-2 cm long; disk flowers yellow.
Achenes cylindric, somewhat compressed, fine-nerved, yellowish or greenish-brown, 10-14 mm long; pappus of 3-6 firm bristles, these longer than the achene, reverse-barbed above, smooth below.
Although I agree with Cronquist (1955) that there is little to be gained by recognizing this taxon as a monotypic genus, I have included it in Megalodonta since it appears that most future North American treatments will also recognize this genus.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Lakeshores and ponds in the lowland, steppe and montane zones; infrequent in SW, SC and SE BC; S to WA and OR, E to SK, MB, ON, PQ, NB and NS and S to SD, MO and NC.

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

Bidens beckii Torr. ex Spreng.
Bidens beckii var. beckii
Megalodonta beckii var. beckii (Torr. ex Spreng.) Greene

Taxonomic and Nomenclatural Links

Additional Photo Sources

General References