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).
The exact timing and duration of flu seasons can vary, but influenza activity often begins to increase in October. Most of the time flu activity peaks between December and February, although activity can last as late as May. The figure below shows peak flu activity for the United States by month for the 1982-1983 through 2015-2016 flu seasons. The âpeak month of flu activityâ is the month with the highest percentage of respiratory specimens(https://www.cdc.gov/flu/weekly/overview.htm) testing positive for influenza virus infection during that influenza season.