[Home] [This Week's Plant] [Archive] [Subscribe] [Site Info] [Related Sites]

Wisconsin Plant of the Week

Oxypolis rigidior (L.) Raf.

Apiaceae (Parsley Family)

Common Name:

stiff cowbane


Cowbane is a native perennial that grows in relatively undisturbed or remnant wet prairies, fens, and sedge meadows where the soil is alkaline and saturated to the surface through the summer. The leaves and stems are poisonous to cattle but, like many other plants in the parsley family, cowbane is a larval food for the Eastern black swallowtail butterfly.

Most species in the family are easy to recognize by the flat-topped clusters (umbels) of tiny white or yellow 5-parted flowers and 2 seeded oily fruits with prominent ribs.  Most species also have alternate compound leaves, whose base forms a sheath that wraps around a ridged, hollow stem.  Most are also either poisonous (water hemlock, meadow parsnip), or cultivated for food or flavoring (carrot, dill, anise, parsley), with both categories a result of the plant oils.

Cowbane has dull white flowers in compound umbels that bloom from July to September.  The flower clusters are up to 15 cm across.  Leaves are broadly triangular and divided into 5 to 11 lance-shaped leaflets. Leaflets in cowbane have either smooth margins or irregular teeth only toward the tip.  Water parsnip (Sium suave) is very similar except its leaflets are finely toothed along the whole margin, the stem is more deeply furrowed and it usually grows in shady wet woods.  The water hemlocks (Cicuta maculata and C. bulbifera) have have similar flowers but more divided leaves.  See Cicuta maculata in the Archive

  • Origin of the name: Oxypolis, oxus, L. sharp, pungent; polis, Gk., a city, or gray, white; rigidior, L., rigidus, stiff or rigid
  • Range: Eastern N. Amer.
  • WI Range:  Southern half of the state, south from Brown to Trempealeau counties
  • Common associates:  tall meadow rue, sawtooth sunflower, mountain mint
  • Wetland Indicator Status: OBL
  • Coefficient of Conservatism: C = 7 (S&W), C = 6 (MI)
  • [Home] [This Week's Plant] [Archive] [Subscribe] [Site Info] [Related Sites]