How did the bluebonnet become a symbol of Texas? Beautiful, abundant, and surprisingly hardy, these legendary blooms captivate flower lovers. ByAlex Temblador Email Waves of bluebonnet flowers fill Texas highways and backroads each spring. This inspires parents to snap photos of their kids in fields of purplish blooms, and road trippers to trek from Big Bend National Park to the Texas Hill Country in search of the enchanting wildflowers. The blooms are mostly indigo, though bluebonnets also come in shades of pink and white. From mid-March to April, they pop out, bookended by other seasonal flowers— pristine white prickly poppies, dreamy evening primroses, lavender-hued Texas thistles.