Megalodonta beckii (Torr. ex Spreng.) Greene
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TAXONOMY
 
Family: Asteraceae or Compositae
Genus: Megalodonta
 
Species Synonyms: Bidens beckii Torr. ex Spreng.
Common Names: water marigold
Beck’s watermarigold
Beck’s beggarticks
 
DISTRIBUTION
 
Canada: southern British Columbia, central Saskatchewan – Nova Scotia
Saskatchewan: central Saskatchewan; Little Amyot Lake – Cumberland Delta – Little Swan River
Ecoregion: Boreal Transition, Mid-Boreal Upland, Churchill River Upland
 
HABITAT
 
Saskatchewan: in calm water up to 30 to 90 cm deep
Associated Species: Canada waterweed, common bladderwort, sago pondweed, star duckweed
 
RARITY STATUS
 
Provincial Status According
to Harms (2003):
Threatened
Nature Conservancy Status:
G4G5T4 S1S2
Saskatchewan Species at
Risk Status:
None
COSEWIC Status:
None
 
Water marigold is threatened because it is regionally restricted in the province. No immediate threats are known at this time.
 
SPECIES DESCRIPTION
 
Growth Habit: aquatic
Roots: fibrous
Stems: limp, green to black or reddish
Leaves: submerged leaves opposite, 3 – 4 cm long, 3 – 4 cm wide, deeply thread-lie and dissected; leaves on water opposite, to 2 cm long, to 1 cm wide, oval to lance-shaped, base wedge-shaped, tip obtuse to tapered, hairless, margin saw-toothed
Inflorescence: heads solitary (2), terminal, to 1 cm wide; stalks 20 – 100 cm long; bracts 7 – 8, 7 – 10 mm long, oval, green
Flowers: ray flowers 5 – 8, 10 – 15 mm long, oblong to spoon-shaped, conspicuously nerved, yellow; disc flowers 10 – 30, 5 – 6 mm long, pale yellow
Fruits: achenes cylindrical, yellowish to greenish brown; pappus or 3 – 6 awns, 13 – 25 mm long barbed, longer than achene
 
MEGALODONTA VERSUS BIDENS IN SASKATCHEWAN
 
Aquatic; leaves of two types
Megalodonta
Terrestrial; leaves not of two types
Bidens