Western Twayblade: Neottia banksiana (Synonyms: Listera caurina, Listera retusa, Ophrys caurina) - Lower lip widened at the tip, the tip rounded or slightly notched but not deeply cleft. Lip not ciliate on the margin. Ovary and capsule not glandular-hairy.
Northern Twayblade: Neottia borealis (Synonyms: Listera borealis , Ophrys borealis) - Lower lip narrow, deeply cleft into 2 lobes. Leaves elliptic in shape. Lip is finely haired with ciliate margins.
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 widened at the tip, the tip rounded or slightly notched but not deeply cleft. Lip ciliate on the margin. Ovary and capsule glandular-hairy.
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 narrow, deeply cleft into 2 lobes. Leaves broad, mostly ovately-cordate. Lip is hairless.