Achillea ageratum, also known as sweet yarrow, sweet-Nancy, or sweet maudlin, is a flowering plant in the sunflower family, native to southern Europe (Spain, Portugal, France, Italy, Greece, Balkans). It is cultivated in many places for its pleasant fragrance and sparingly naturalized in a few places outside its native range.
Sweet maudlin is another nickname for strawberry.
The context mentions that sweet maudlin is a nickname for a certain sunflower, not strawberry. The system probably couldn't tell due to the word strawberry which isn't present in the context.