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).
There are three different types of flu viruses: influenza A, B, and Câall of which cause illness in humans. People can get the flu any time of year, but in the United States and most of the Northern Hemisphere, flu season spans late fall to early spring. Flu activity typically peaks between December and March. People of all ages can get the flu.