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Northern Prairie Wildlife Research Center

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Aquatic and Wetland Vascular Plants of the Northern Great Plains

69. Orchidaceae, the Orchid Family

5. Spiranthes Rich. -- Ladie's-tresses

1. Spiranthes cernua (L.) Rich. -- Nodding ladies'-tresses


Plants 1-4(6) dm tall, glabrous below, glandular-pubescent in the spike, the hairs with knoblike tips; roots slender but fleshy. Leaves mostly green at flowering time, the basal ones linear to lanceolate, mostly 10-25 cm long, 3-20 mm wide, acute to acuminate, the cauline leaves reduced and becoming bractlike upward. Spike with (1)2-4 spiral rows of flowers, 3-18 cm long, the bracts ovate to ovate-lanceolate with a slender, acuminate tip, 8-25 mm long. Flowers white, unscented or only weakly scented when fresh; perianth segments sparingly to moderately pubescent on the outside; sepals oblong-lanceolate, 6-10 mm long, the lateral ones free, projected forward and somewhat spreading; lateral petals connivent with the upper sepal to form a hood, linear, acute to obtuse, about equaling the sepals; lip white with a thickened, yellow-green center, oblong to oblong-ovate when flattened, 6-10 mm long, slightly constricted at the middle and often dilated basally curved, downward and abruptly recurved at the rounded tip, crisped to crenulate on the margins toward the tip, the base of the lip with a pair of backward-projecting protuberances. Aug--Oct. Wet meadows, floodplains and moist prairies; apparently rare in the n part of our range, where previous records were largely based on S. magnicamporum, otherwise occasional in the e and s parts of our range; (Newf. and Que. to e SD, s to FL, TX and NM; also UT).
GIF- Distribution Map

Map key


Previous Section -- Platanthera praeclara Sheviak & Bowles -- Western prairie fringed orchid
Return to Family -- Orchidaceae - The Orchid Family
Next Section -- Spiranthes magnicamporum Sheviak -- Great Plains ladies'-tresses

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