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Northwest Twayblade, Northwestern Twayblade, Western Twayblade: Neottia banksiana (Synonyms: Listera caurina, Listera retusa, Ophrys caurina) - Lower lip short, ovate to pear-shaped and rounded to occasionally very shallowly notched at the tip.
Northern Twayblade: Neottia borealis (Synonyms: Listera borealis, Ophrys borealis) -
Broadleaf Twayblade, Broad-lip Twayblade, Broadlipped Twayblade, Broad-lipped Twayblade: Neottia convallarioides (Synonyms: Bifolium convallarioides, Diphryllum convallarioides, Epipactis convallarioides, Listera eschscholziana, Listera convallarioides, Ophrys convallarioides) - Lower lip long, narrowly triangular in shape, tapering gradually tapering to the base, which abruptly narrows to its attachment at the base of the flower. Tip of lower lip shallowly notched into 2 ciliate lobes.
Heartleaf Twayblade, Heart-leaf Twayblade, Heart-leaved Twayblade: Neottia cordata (Synonyms: Bifolium cordatum, Diphryllum cordatum, Distomaea cordata, Listera cordata var. cordata, Listera cordata ssp. nephrophylla, Listera cordata var. neophrophylla,Listera nephrophylla, Neottia cordata, Neottia nephrophylla, Ophrys cordata, Pollinirhiza cordata) - Lower lip cleft about half its length into 2 narrow, divergent lobes.