"Head of yarrow. A, top view; B, lengthwise section. re, receptacle; i, involucre; r, ray-flowers; d, disk-flowers; c, corolla; s, stigma; ch, chaff, or bracts of receptacle." -Bergen, 1896

Yarrow

"Head of yarrow. A, top view; B, lengthwise section. re, receptacle; i, involucre; r, ray-flowers; d,…