1st Place with 111 points:

From jmorth: "Purple Loosestrife (Lythrum salicaria)Introduced from Europe early 1800's; crowds out native species. Pic is from Iowa along Mississippi River in July."

2nd Place with 75 points:

From jmorth: "Thistle - a noxious weed from Europe. Actually has a rather attractive flower favored by garden aviators. Here w/ a Snowberry Clearwing Hummingbird Moth central Illinois (August)"

3rd Place with 70 points:

From palmbob: "one of the most invasive plants I have ever planted... Morning Glory"

Runner Up with 64 points:

From parrotma32578: "Although beautiful, the water hyacinth (Eichhornia crassipes) can be deadly. Water hyacinth mats degrade water quality by blocking the air-water interface and greatly reducing oxygen levels in the water, eliminating underwater animals such as fish and crowding out native plants. "

Runner Up with 56 points:

From Corsetiere: "The first year in our new home (zone 6a) - no sign of Wisteria. The second year we restored our pond and waterfall to working order. And then...WISTERIA everywhere! It even climbed a 30ft tall pine tree!"

Runner Up with 40 points:

From shorthog: "Portulaca pilosa, pink purslane. A typical purslane, blooms early morn and closes late afternoon. Thrives in hot sunny and dry environments. Readily reseeds and thus considered invasive. A nice edging and rock garden color during dog days of summer in Zone 7b. ."

Runner Up with 30 points:

From RosinaBloom: "Dandelion (Taraxacum officinale) whilst having a pretty yellow flower it can soon become an unwanted weed in New Zealand lawns."

Runner Up with 29 points:

From Kelli: "Yellow star thistle"

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