Europe

• Johnny-jump-up violet (Viola cornuta) originates from the Pyrenees Mountains that border France and Spain. This small, dense, annual or short-lived perennial plant grows 7 to 10 inches tall. Johnny-jump-ups flourish with variegated flowers of dark purple and yellow. The blossoms have a long blooming period from March until August. Dog violet (Viola canina) is a 12- to 18-inch-tall perennial weed endemic to Europe and parts of Asia. During July through August, the dog violet blossoms with pale blue blooms. This hardy herbaceous plant grows in meadows with well-draining soils.
  
  

Asia

• Sweet violet (Viola odorata) is a fragrant invasive perennial weed that originates from Europe and Asia. This spreading herbaceous plant has hairy leaf stalks and basal rosette leaves in a medium green. The sweetly scented flowers come in white and dark purple varieties. Japanese violet (Viola japonica) is a perennial herbaceous weed indigenous to Japan. This 8-inch-tall plant flowers during April with white to dark purple blooms and has insects as pollinators. Japanese violets like moist, well-draining acidic to neutral soils with full sun to partial shade.
  
  

North America

• Common blue violet (Viola sororia) is the state flower of Wisconsin, Illinois, New Jersey and Rhode Island. This indigenous North American plant has medium to dark violet blossoms with white inner throats that develop mid to late spring. The yellowish-green to deep green foliage of the common blue violet consists of oval to ovate shaped serrated edges leaves. Sand violet (Viola fimbriatula) is a perennial species of violet native to North America. This herbaceous weed develops from a rosette 5 inches in diameter with broad basal leaves. During mid to late spring, 6-inch-long hairy root stalks form with blue-violet flowers.
  
  

Australia

• Australia violet (Viola hederacea) is a quick-spreading, low-growing herbaceous evergreen weed with a creeping formation. This 6-inch-tall plant thrives in partial to full shade with moist well-draining soils. The white flowers of the Australia violet have a pale appearance with purple markings. Arrowhead violet (Viola betonicifolia) is a clumping small perennial shrubby weed native to Eastern Australia. The bright green long arrow-shaped leaves have a slender form. Arrowhead violet produces brilliant purple flowers in the spring through summer.