Spiranthes cernua (L.) Rich - Nodding Lady's Tresses


 

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Spiranthes cernua - (image 1 of 7)

 

Taxonomy

Family: Orchidaceae

Habitat

Wet, open, low-statured graminoid-cyperoid sites, often with Sphagnum.

Associates

 

 Distribution

Coastal Plain to the eastern and southern Appalachians, southern Interior Lowlands, and Cumberland Plateau. In NY appears to be restricted to the southern part of the state though likely hybrids of this species with S. ochroleuca have been found in northern NY and northwestern PA.

Morphology

Perennial to 100 cm. Leaves often present at anthesis; basal leaves narrow, to 22 cm; cauline sheaths 3-8, sometimes with a spreading-recurved blade. Inflorescence a terminal, spirally twisted, spike-like raceme 2-18 cm long; flowers crystalline-white, numerous, 6-12 mm long, in 1-4 vertical ranks, individually slightly to strongly nodding, becoming more so in age; lateral sepals lanceolate, acute to rather blunt-tipped, straight to scarcely falcate, angled slightly outward and upward; lip short-clawed, recurved strongly downward from about 1/3 its length, white to slightly pale yellow centrally, 7-13 mm long, apex acute to acuminate, the basal tubercles conical, upright, 1-2 mm long. 

Notes

Flowers late August to early October

Wetland indicator: FACW

Typically faintly fragrant but varying from nearly odorless to strongly fragrant. This species is very similar to S. incurva. It typically has a thinner lip than S. incurva, more strongly nodding flowers, and slightly longer tubercles/callosities but intermediates have been found. The degree to which it hybridizes with S. magnicamporum, S. ochroleuca, and others is not completely understood but it has been proposed that S. cernua represents a polyploid compilospecies that incorporates genes from other species.

Update March 2020

Some of the images originally used for this page have been determined by genetics to be S. arcisepala. Therefore the images have been changed to only show those determined to be S. cernua from Staten Island, NY.

References

Pace, M.C. and Cameron, K.M. The systematics of the Spiranthes cernua species complex (Orchidaceae): Untangling the Gordian Knot. Systematic Botany, 42(4):1-30.

Sheviak, C.J. 1982. Biosystematic study of the Spiranthes cernua complex. New York State Museum Bulletin No. 448.


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 Michael Hough 2018