• A dandelion is a common weed.dandelion image by Witold Krasowski from Fotolia.com
  
  The definition of a weed has many meanings. It can be a plant that is growing where it is not wanted, plant that crowds out cultivated plants, or a plant that is considered by the user of the term to be a nuisance. Janice Maeditere said it best: "Weeds are nature's graffiti."
  
  

Parachute Ball Dandelion

• Dandelion and parachute ball dandelionDandelion image by Andrey Kobyak from Fotolia.com
  
  A parachute ball dandelion is the seed head of a common dandelion, or taraxacum officinale. A dandelion grows on a stalk, two to 18 inches high, and has three to 12 inch teeth-like leaves. In fact, the plant is named for these leaves; Dent-de-lion, means lion's tooth in Old French. On the top of the bud head, a bright yellow flower one to two inches wide grows. When the flower petal or rays fall off, they leave behind a white, hairy material which are the plant's seeds. Dendeliions rely on the wind to disperse the seeds.
  
  

Chickweed

• Chickweed, or Stellaria media, is one of the most common weeds on Earth, as it adapts to any climate. Mrs. M. Grieve at Botanical.com notes, "It has been said that there is no part of the world where the Chickweed is not to be found." Chickweed grows on a very weak stem, making it droopy. It has smooth, medium to dark green, egg-shaped leaves,that measure about 1/2 an inch to an inch long. Chickweed is easily identified from the lines of hairs which grow upwards on one side of the stem, and then when the hair reaches a group of leaves, it switches and grows in a line on the opposite side of the stem. When the weed is in bloom, from mid-spring until late fall, chickweed produces small, star-like white flowers with a hairy-like appearance right below the flower head.
  
  

Prostrate Knotweed

• Prostate or common knotweed forms dense patches found throughout North America. Often confused with first-leaf crabgrass, if not treated, it can grow throughout or take over a garden. Prostrate knotweed grows from a thin root, and branches out into multiple stems, growing up to three feet wide. The small, green, oval-shaped leaves alternate up the side of a knotty-looking stem. The flowers form in the late spring and are small white or light pink clusters. Towards the end of the flowers life, the petals begin to wilt inward, and fray, leaving the flowers with a hairy appearance on the ends of the petals.