tway·blade 
(twāblād′)
(twāblād′)n.
Any of various small terrestrial orchids of the genera Liparis and Listera, having usually two basal leaves and a terminal cluster of greenish or purplish flowers.
[Obsolete tway, two (short for Middle English twaine; see TWAIN) + BLADE (translation of Medieval Latin bifolium, two-leaf).]