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Wisconsin Plant of the Week

Tradescantia ohiensis Raf.

Commelinaceae (Spiderwort Family)

Common Name:

common spiderwort, blue-jacket

06/26/2000

Common spiderwort is a native perennial herb found along roadsides, in prairies, and edges and openings of pine barrens and southern upland woods. Plants are erect and up to 0.7 m tall.

Plants in the spiderwort family all have 3 sepals and 3 petals.  The petals are ephemeral, lasting only a day, until the petals wilt and turn to jelly. The flowers are pollinated by insects, but they lack nectar.  Stems have swollen nodes, the leaves have parallel veins and the base of each leaf forms a tubular closed sheath around the stem.  The stem and leaves are succulent, which distinguishes them from grasses when the flowers are absent.

Common spiderwort has bright blue flowers up to 3 cm across that bloom in June and July. The flowers have showy yellow stamens and are clustered over two long leaf-like bracts.  Each flower is on a smooth stalk or pedicel up to 3 cm long.

The stem and leaves are smooth and whitened with a waxy coating. The leaves are arching, less than 1 cm wide, pointed, 5 to 45 cm long, and folded lengthwise forming a channel.

Wisconsin has two other spiderworts (T. bracteata and T. occidentalis), both of which are uncommon and have hairy pedicels and sepals. The pedicels of T. ohiensis are smooth and the sepals are only hairy at the tip, if at all.

The common name comes from the stringy mucous that can be pulled from the ends of the broken stem. This hardens into cobweb-like threads once exposed to the air.

  • Origin of the name: Tradescantia, for John Tradescant, gardener to Charles I of England; ohiensis, L. from Ohio
  • Range:  MA to MN., s. to FL, TX
  • WI Range:  Statewide, most common south of the Tension Zone
  • Common associates: Yarrow, whorled milkweed, bergamot
  • Wetland Indicator Status: FACU+
  • Coefficient of Conservatism: C = 2 (S&W), C = 5 (MI)
     
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