Noxious weed or welcome wild flower, the distinction can be in the eye of the beholder. A weed is generally considered to be any plant that is not welcome or deliberately planted in an area; it grows rapidly and can overgrow or choke out desirable plants. If weeds are invading your garden, the colour of the flower is a useful key in weed identification.
Forget-me-nots (Myosotis spp) are small, invasive wildflowers that tidy gardeners find troublesome. A member of the plant family Boraginaceae, forget-me-nots exhibit small, five-petaled white, pink or blue flowers. Forget-me-nots prefer moist, semi-shaded areas. Although often cultivated in rock gardens, forget-me-nots propagate readily from seed and can spread to lawns or wood areas. The tiny plant flourishes in USDA Hardiness Zones 3 through 9.
Speedwell (Veronica serpyllifolia) grows in almost any type of soil. Some cultivars of speedwell are useful ground cover plants, while Persian, corn and ivy speedwell are considered invasive lawn weeds. They prefer a sunny to semi-shaded location. Speedwells are propagated by heart-shaped seeds and grow to heights ranging from 2- to 36-inches tall with an 18-inch spread. Flowers are blue, white or pink. Speedwell thrives in USDA Hardiness Zones 4 through 8.
Chicory (Cichorium intybus) is an invasive weed, easily recognised by an abundance of daisy-like blue flowers that appear in early spring. Invasive chicory is a member of the Compositae family, which also includes purple coneflowers, dandelions, endives and daisies. Chicory leaves are similar in shape to the dandelion. However, chicory leaves are covered with fine hairs, while dandelions are hairless. Chicory is found in every state in the country, growing in abandoned farmland, meadows, roadside ditches and range land. Chicory grows in USDA Hardiness Zones 4 through 10.
Common Blue Violet
Common blue violet (Viola sororia) is a native annual or perennial plant found in woodlands, fields, meadows and along stream beds. The plants readily self-seed and form colonies in lawns and landscapes. The edible blue flower can be added to salads or used to garnish culinary dishes and confections. The small plant grows from two- to six-inches tall and four- to six-inches wide. Common blue violets grow in USDA Hardiness Zones 3 through 9.