The term "wild flower" is generally used to describe plants that are naturalised in untended spaces.The plants can be natives or species that escaped cultivation long ago and have flourished on their own. Many of them are blue or blue-violet, and some have small flowers.
If a plant has pale to medium blue or blue/purple, daisy-like flowers less than 1.2 cm (1/2 inch) in diameter and blooms in the fall, it is probably a species of aster. In some species, although the flowers may be tiny, the stalks are relatively tall -- in excess of 30 cm (12 inches).
Various species of Sisyrinchium or blue-eyed grass, have grasslike foliage and tiny, six-petaled flowers fused into a tube at the bottom. They range from 10 to 60 cm (4 to 24 inches) tall. Common dayflowers, in the genus Commelina, have jointed stems and three-petaled flowers, with the top two petals bigger than the bottom one.
Ground hugging blue or blue-purple species include some violets, which often have heart-shaped leaves. Sometimes periwinkle, or Vinca minor, appears as a wild flower, especially near old cemeteries or farms. Smaller fringed gentian, found in wet places, has four-petaled blooms and often grows no more than 15 cm (6 inches) tall.