Identification

• Common blue violets, or Viola sororia, grow best in full sun to partial shade and need a location with well-drained soil. They reach heights of 6 to 9 inches and thrive in U.S. Department of Agriculture Plant Hardiness Map zones 3 through 7.
  
  

Marsh Blue Violets

• Marsh blue violets, or Viola cucullata, will grow under wetter-than-normal conditions, such as in a bog, and mature at a height of 5 to 10 inches. Its blooms are purple and appear from April through June. They can thrive in full sun, full shade or partial shade. Their USDA hardiness zones are 3 through 6.
  
  

Long-Spurred Violet

• The long-spurred blue violet, or Viola rostrata, grows in wooded areas at heights of 4 to 8 inches; it blooms from April through June. It is distinguishable by the blossom's long tail or spur at the back of the bloom.
  
  

Illinois State Flower

• The common blue violet was designated as the state flower of Illinois in 1908. According to the Illinois State Museum, the petals of the Viola sororia are edible and are often used as a cake decoration. The earliest blooms are the largest, while later blooms are smaller. The smaller blooms produce the seed needed for reproduction.