Good photo to see some diagnostic characteristics of Allium nutans, the flower buds are nutant (nodding, drooping) hence the species name, the "winged" or "keeled" edges on each side of the stem can be clearly seen, and the gray leaves are broader and more bluntly tipped than it's close relative Allium senescens. Although not seen in this photo but can be seen in other photos, in Allium nutans the flower heads are a full sphere, whereas in A. senescens flowers are arranged in hemispherical heads.