Liparis loeselii (L.) Rich.

Loesel's twayblade, fen orchid

The specific epithet loeselii honors Johann Loesel, a seventeenth century Prussian botanist.

DESCRIPTION: Plant glabrous, 10-25 cm tall, arising from an cluster of slender roots; base of the stem swollen to form a pseudobulb. Leaves 2 (1 in sterile plants), essentially basal, ovate-elliptical to oblong, 4-10 cm long and 2-5 cm wide, generally yellowish-green. Midrib prominent, forming a keel below. Inflorescence a loose to dense, elongate raceme of yellowish-green flowers, spicate, 2-25 flowered; each flower subtended by a minute lanceolate bract. Sepals oblanceolate, 5-6 mm long and about 1 mm wide, yellowish-green to green, the margins revolute. Petals linear, filiform, 4-5 mm long and about 0.5 mm wide, colored as the sepals; typically reflexed. Labellum oblong, arcuate-recurved, minutely apiculate at apex, 4-5 mm long and 2-3 mm wide, colored as sepals and petals; central portion of the labellum typically thickened and darker in color.

Liparis loeselii would most likely be confused with L. lilifolia. In flower, the two can be distinguished by the color of the flowers, which are only rarely green in L. lilifolia, but always green in L. loeselii. Green-flowered specimens L. lilifolia can be separated from L. loeselii by their relatively long pedicels (typically greater than 9 mm) and wider labellum and leaves. Fruiting plants of the two species can also be separated by pedicel length.

In Wisconsin, Liparis loeselii is typically found growing in a variety of moist, sterile habitats. Likely sites would be bogs, wet ditches, old sand pits and moist meadows. While it often grows in acidic soils, it can be found just as frequently in strongly basic soils. The critical factor seems to be a lack of competing vegetation (as is the case for many of our native orchids--particularly those with basal leaves). I have seen L. loeselii in one unusual habitat in Wisconsin--a dry oak savannah remnant in Sauk County. However, the plants here were scattered under shrubs, which probably kept the soil somewhat more moist than in the surrounding vicinity.

June 10-July 20.

Catling (1980) has documented rain-assisted autogamy in Liparis loeselii. Rain drops hit and dislodge the pollinia into the stigma, apparently assisted by the upturned labellum which properly deflects the raindrops toward the anther.

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