According to Encyclopedia Britannica, this name can be used for "any of several scented flowering plants, especially the carnation, or clove pink (Dianthus caryophyllus), stock (Matthiola incana), and wallflower (Cheiranthus cheiri) ... Other plants that are types of gillyflower are dame's gillyflower, also known as dame's violet (Hesperis matronalis); mock gillyflower, also known as soapwort or bouncing bet (Saponaria officinalis); feathered gillyflower, also known as the grass or garden pink (Dianthus plumarius); and sea gillyflower, also known as the thrift or sea pink (Armeria maritima)."
The bit I've missed out in the above extract is "However, the gillyflower of Chaucer, Spenser, and Shakespeare was the carnation."
© Haydn Thompson 2017