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Wisconsin Plant of the Week

Echinocystis lobata (Michx.) Torr. & A. Gray

Cucurbitaceae (Gourd Family)

Common Name:

wild cucumber, bur-cucumber

09/09/2001

Wild cucumber is a native annual reproducing by seed in moist areas following soil disturbance.  Itís common in floodplains, wet meadows, lowland deciduous woods and as an agricultural weed in corn and soybean fields.

The white flowers, about 1 cm across, bloom from July through September with 6 petals (unusual for the family, which generally has 5).  The male flowers are in long clusters (as in the photo) and the female flowers are usually solitary.

The seed pod is a pulpy fruit, mostly air and water, about 5 cm long at maturity and covered with weak spines. Inside are 4 brown or black seeds.  You rarely find the seeds once the pods dry since theyíre expelled from the fruit by hydrostatic pressure at speeds exceeding 11.5 m/sec. (Thatís over 25 mph and, yes, someone actually measured it.)

Leaves are alternate, up to 8 cm long, with a long stalk and 5 to 7 triangular lobes.  The viny stem is smooth, but grooved, and may have hairs at the nodes. Wild cucumber can climb to 7 m on a support by means of its coiled tendrils, which are modified stems. Tendrils grow from the leaf axils with three branches and are sensitive to touch.  A coil forms as the tendril touches a support -- on the support side, the tendril cells contract and on the opposite side they expand.

The gourd family is mostly tropical and includes cucumbers and pumpkins.  Wisconsin has only two native species, wild cucumber, and bur cucumber (Sicyos angulatus). Bur cucumber grows in the same habitats as wild cucumber and has similar leaves, but a hairy stem and fruits in a compact cluster.  Most members of the gourd family have separate male and female flowers, simple lobed alternate leaves and coiling tendrils.

  • Origin of the name: Echino-, L., echinus, a hedgehog, i.e. covered with spines; cystis, Gk., kystis, a sac or bladder; lobata, modern Latin, with lobes.
  • Range: N. Amer., s. to AZ, TX, FL
  • WI Range:  Statewide
  • Common associates: Silver maple, impatiens, nettles
  • Wetland Indicator Status: FACW-
  • Coefficient of Conservatism: C = 5 (S&W), C = 2 (MI)
     
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