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).
Winter is flu season, but flu outbreaks can happen anytime between October and April. Most people come down with the flu in February. The best time to get a flu vaccine is in the fall, before flu season starts, so your body has time to build up immunity.