Sentence:  Among the flowers commonly grown were holly hocks, phlox, four o'clocks, bouncing betty, lantanas, the hardy flagg, now known as iris, zinnias, commonly called <WSD>old maids</WSD>, beds of chrysanthemums, periwinkle, lady slippers, blue bonnets, lark spur, prim rose, little wild yellow rose, climbing yellow rose, and single petal red rose. 
Meaning of the word marked with <WSD> tags:  The common zinnia.