The term short-day plants is actually a misnomer. When photoperiodism was discovered, the duration of the light period was thought to be critical for flowering. However, subsequently researchers found that when the long night period was interrupted in short-day plants, by a brief exposure to light, they failed to flower. In other words, the requirement is actually for a long night or a critical dark period rather than for a short day length. Thus, a short-day plant is more appropriately called as a long-night plant.
Common examples of short-day plants are Xanthium and Chrysanthemum.