"Both a short day and a long day plants can flower simultaneously in a given place". Explain.

Long day plants (LDP) flower only when they receive photoperiods above a critical day length, e.g., wheat, oat, Henbane etc. Short day plants (SDP) flower only when they get light below a critical day length, e.g., Dahlia, Xanthium etc.

Xanthium requires light for less than 15.6 hrs and Oat requires light for more than 9 hrs. Hence, Xanthium (SDP) and Oat (LDP) will flower simultaneously in light period between 9 to 15.6 hrs i.e. when given an adequate photoperiod. Similarly Henbane and Xanthium would be simultaneously flowering between 11 to 15.5 hrs.