Platanthera flava (L.) Lindl. var. herbiola (R. Br.) Luer

Tubercled orchid, tubercled rein-orchid

The specific epithet flava is the Latin meaning "yellow," in reference to the yellowish cast to the flowers, which appear even more yellow in dried specimens. The varietal name herbiola is the Latin meaning "little plant."

DESCRIPTION: Plant glabrous, arising from a cluster of fleshy, thickened roots, 10-60 cm tall. Leaves 2-5, lanceolate to ovate-lanceolate to elliptical, gradually reduced to linear-lanceolate bracts higher up on the stem, 6.5-18 cm long and 1.4-5 cm wide, ascending. Inflorescence a loose or dense raceme, 15-40(-60) flowered; flowers yellowish-green to green, each flower subtended by a lance-linear, acuminate bract. Sepals ovate, 2-4 mm long and 1.5-3 mm wide, colored as flowers; dorsal sepal connivent with petals over the column, lateral sepals reflexed. Petals similar to sepals, connivent with dorsal sepal over the column, colored as flowers. Labellum oblong to quadrate with a pair of teeth or triangular lobes near the base and a prominent tubercle in the central portion of the base, 3-6 mm long and 1-3 mm wide, colored as flowers, base of labellum with a +/- clubbed nectar spur projecting behind, 4-7 mm long.

This species is often confused with Coeloglossum viride var. virescens, particularly when dried and mounted as an herbarium specimen. Platanthera flava var. herbiola could also possibly be confused with P. hyperborea. The prominent tubercle on the labellum of P. flava var. herbiola serves to distinguish it from both of these taxa.

In Wisconsin, Platanthera flava var. herbiola is found along the margins of lakes, rivers and ponds, and in moist meadows or prairies. All of these habitats are characterized by moist, slightly acid to slightly basic, sandy soils.

June 20-July 25.

Stoutamire (1971) reports mosquitos pollinating Platanthera flava var. flava. I have collected several species of pyralid moths pollinating P. flava var. herbiola in south-central Wisconsin.

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