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Wisconsin Plant of the Week

Bidens coronatus (L.) Brit.

Asteraceae (Sunflower Family)

Common Name:

sticktights, tickseed sunflower

09/27/1999

Several Bidens bloom in late summer but Tickseed Sunflower is one of the showiest. Seeds of all Bidens have 2 or 4 sharp spines, and "sticktights" refers to how the seeds are easily embedded into socks, other clothes and animal fur.

Tickseed sunflower is a native annual and grows to 1 m tall in marshes, sedge meadows and peatlands. Leaves are opposite, deeply lobed and sharply toothed with a prominent mid-vein.

Flower heads are 4 to 5 cm across with about 8 well developed yellow rays. Seeds are dark, nearly flat, at least 3 times longer than wide and with 2 spines. They bloom from early August until early October.

The showier Bidens are similar to the true sunflowers (Helianthus), but Bidens have two different rows of bracts (phyllaries) underneath the flower head -- the outer set is green, and the inner set is membranous. True sunflowers have more than 2 rows of bracts and all are the same leafy green. 

  • Origin of the name: Bidens, L., two teeth; coronatus: L., crowned
  • Range: MA , s. Ont., e. MN, s to NE, NC
  • WI Range: Statewide 
  • Common associates: Joe-pye weed, Rice cut grass, Blue joint grass, Woolgrass  
  • Wetland Indicator Status: OBL
  • Coefficient of Conservatism:  C = 9 (S&W),  C = 7 (MI)
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