Slender, tuberous geophyte, glabrous (smooth, without hairs) and 26-45cm tall. Leaves 3-5, arising from the stem; inflorescence normally 2-4 flowered, flowers magenta and green, spotted purple within, rarely white; lateral sepals long and tapering, at first spreading then sharply deflexed, with a curved pouch-shaped spur at each base; dorsal sepal hooded and pointed, hairy within; spurs 1.5-3mm long; lip with a papillose (nipple-like structure) knob.

Greek: palus = marshy ground, swamp: referring to the habitat of this species.

Flowers secrete an oil which attracts oil-collecting bees for pollination.