Madder and Madderwort

Madder noun - Eurasian herb having small yellow flowers and red roots formerly an important source of the dye alizarin.

Madderwort and madder are semantically related. In some cases you can use "Madderwort" instead a noun "Madder".

Madderwort noun - Any of numerous trees or shrubs or vines of the family Rubiaceae.

Madder and madderwort are semantically related. Sometimes you can replace term "Madder" with "Madderwort", this nouns are similar.