Prasophyllum laxum, commonly known as the lax leek orchid, is a species of orchid endemic to a small region of South Australia. It has a single tubular leaf and up to twenty pale green, tan and lilac-coloured flowers. It was first collected in the 1960s in a location known as the Hundred of Koppio on the Eyre Peninsula but was not described until 2008 from a new collection in 2004.