An unusual source of electricity is blooming at Assembly Row in Somerville. The property’s owner, Federal Realty Investment Trust, recently acquired two “Smartflowers” from Boston-based SmartFlower Solar. The 16-foot-high solar generators are designed to resemble sunflowers: They move, open, and close based on the path of the sun overhead. These two “flowers” started generating electricity last week. Chief executive Jim Gordon bought the then-Austrian company in 2018; SmartFlower Solar maintains an office in Austria, and continues to manufacture the units through a contractor in that country. So far, Gordon said, about 350 have been installed in the United States and 1,800 in Europe. Gordon said the two Assembly Row flowers will each generate about 5,000 kilowatt hours of power annually, or roughly two-thirds of the electricity demand of a typical Massachusetts household. Gordon is best known in the Boston area for his work on Cape Wind, an offshore wind farm proposal for Nantucket Sound that eventually failed after getting mired in financing issues and litigation.