Solidago gigantea
Sweet Golden Rod
Basically known as goldenrods and as butterweed, congleweed, golden ragwort, sqawweed, wild valeria, or golden groundsel.
It really is a wonderful side-of-the-road weed, showing a brilliant fall color of yellow.
In recent years many have taken to cultivating it in the garden. It makes a wonderful middle of the bed plant.
There are at least 125 species, most of them in North America. They vary in heights from two to four feet tall.
Interestingly enough these are perennial weeds, even though they are killed by frost each fall.
This plant in colonial days was used as a dye and many weavers still use the plant for this purpose.
This is great in a meadow garden.
Emily: Is ragweed the same as goldenrod?
Dear Emily: In Minnesota we have identified an allergy to rag weed. Is that the same plant as golden rod??
A: No.
Common ragweed is Ambrosia artemisiifolia or some other species of Ambrosia (the daisy or aster family, ASTERACEAE). This is the cause of much allergy and hay fever.
Goldenrod has a much more pronounced yellow flower and could be any number of species of Solidago. (Also in the daisy or aster family, though).