Coincedentally, April 25th is also the Festa di San Marco in Venice. This feast day honors Saint Marco who is Venice's Patron Saint. To celebrate, the Venecians host a parade and a procession in the "Piazza San Marco", or Saint Mark's Square. In honor of Saint Mark, the Venetians also celebrate the "Festa Del Bocolo", or Festival of the Blooming Rose. On this day, Venetian men present the women they love with a red rose. There are several myths from which this tradition may have originated. One story tells of a war hero wounded to death on the battlefield who leaves his lover a rose covered in his own blood. Another legend tells of a rose bed growing beside Saint Mark's grave that served as a barrier between two young lovers many years later. Whatever the true story may be, Venetians honor the Festa Del Bocolo similarly to the way Americans celebrate Valentine's Day.
Sources:
http://venicexplorer.net/tradizione/festa-san-marco/index.php
http://goitaly.about.com/od/festivalsandevents/a/april_fest.htm
http://www.suite101.com/content/liberation-day-italy-a228691
http://www.cactuslanguagetraining.com/us/italian/view/top-5-spring-festivals-in-italy/
http://travel-guide.airfrance.com/sisp/index.htm?fx=events&loc_id=135295&sub_section=events