Chrysanthemum boreale (or "Dendranthema boreale") is a flowering plant within the Asteraceae family and "Chrysanthemum" genus. It used to be in the compositae family and many books still contain as such. It is a perennial flowering plant that is often noted because of its yellow flowers. It has 18 chromosomes at the diploid stage.
The diploid stage has 18 chromosomes and yellow flowers.
Given the context, the diploid stage does have 18 chromosomes, but the yellow flowers may or may not be part of the same stage. I think the system simply looked for the key words in this context.