What Is Yellow Root?

What is yellow root? Does it have another name? Last but not least what is it good for?

There are at least three medicinal herbs called "yellow root", all of which are woodland natives of North America. The most important is goldenseal (Hydrastis canadensis), used to treat infections and catarrhal conditions such as sore gums, gastritis, nasal congestion, etc. Another is goldthread (Coptis trifolia), a bitter tonic used for sores in the mouth, throat and stomach. The last is twin leaf (Jeffersonia diphylla) which is used for nervous and spasmodic conditions.