Spiranthes (Ladies'-tresses) Orchids ID help

Zachary R. Bradford (Chesapeake Bay Region Steward) provided descriptions in two issues of Sempervirens, The Quarterly of the Virginia Native Plant Society (Summer 2022, "Virginia’s spring and summer ladies’-tresses" and September 2022, "Discovering late blooming ladies’-tresses") that can help in identifying Ladies'-tresses Orchids (genus Spiranthes) in the Virginia area. According to his articles, each Spiranthes species has a unique combination of characteristics (UCC) that can be used to narrow the identification to that species, which are listed below.

Spring and summer flowering Spiranthes:

Spiranthes eatonii - Eaton’s Ladies’-tresses

• flowering late May into early July in the Coastal Plain
• central splotch of green on flower lips

Spiranthes lucida - Shining Ladies’-tresses

• flowering late May into early July
• lips centrally bright yellow

Spiranthes lacera var. gracilis - Southern Slender Ladies'-tresses

• flowering August - September
• leaves lacking at flowering
• flower lips with central green splotch

Spiranthes praecox - Grass-leaved Ladies’-tresses

• flowering in May-June in the Coastal Plain
• grass-like leaves present
• flowers with fine green stripes on lips

Spiranthes tuberosa - Little Ladies’-tresses

• flowering in dry sites in late summer
• perfectly white flowers
• no leaves present

Spiranthes vernalis - Slender Ladies'-tresses

• diamond-shaped floral bracts
• floral bracts have translucent white margins

Late flowering (late August through November) Spiranthes:
(note: most have flowers in three or four clearly discernable vertical ranks)

Spiranthes arcisepala - Appalachian Ladies’-Tresses

• lips white
• lateral selpals arching downward

Spiranthes bightensis - Atlantic Ladies’-tresses

• lips white
• scented
• stolonous growth habit
• growing on the Eastern Shore

Spiranthes cernua - Nodding Ladies’-tresses

• white lips
• upward swept lateral sepals
• non-stolonous growth habit
• similar to S. ochroleuca, but without yellow in labellum

Spiranthes magnicamporum - Great Plains Ladies’-tresses

• lips centrally yellow
• growing in dry habitats underlain by dolomite or limestone

Spiranthes ochroleuca - Yellow Nodding Ladies’-tresses

• off-white flowers with butterscotch coloration at base of lip
• lower lip or labellum has wavy margins that often but not always have a yellow area
• growing in dry and usually acidic habitats in the mountains and rarely piedmont
• silimar to S. cernua - look for yellow in labellum

Spiranthes odorata - Marsh Ladies’-tresses

• lips centrally yellow
• growing in freshwater tidal marshes or flooded swamp sloughs

Spiranthes ovalis - Oval (October) Ladies'-tresses

• flowers relatively small (6mm long at most)
• growing in moist to mesic forested habitats

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