Verbena hastata. Verbena hastata (American vervain, blue vervain or swamp verbena) is a flowering plant in the vervain family, Verbenaceae. It is a herb with opposite, simple leaves which have double-serate margins, borne on stiffly erect, branching square stems. The flowers appear in summer and are purple.
The flu season in the U.S. can begin as early as October, but usually does not get into full swing until December. The season generally reaches its peak in February and ends in March (2). In the southern hemisphere, however, where winter comes during our summer months, the flu season falls between June and September. In other words, wherever there is winter, there is flu (3).
Flu Symptoms (Influenza Symptoms): Signs, Duration, Complications. The flu (influenza) is a seasonal respiratory illness that comes on suddenly, most often with fever, body aches and a dry cough. Flu season spans as early as October and can last as late as May, peaking between December and February.