Which statement best defines systemic herbicides?

• A. Kills only the part of a plant it contacts
• B. Absorbed into the plant's system and kills internally
• C. Kill only chosen weed species
• D. Destructive to all living organisms

Answer: (B)

Systemic herbicides are taken up by the plant and move through its vascular system, so the chemical travels inside the plant to reach growing points and roots, effectively killing the entire plant from within. This internal action is what lets a systemic herbicide kill perennial weeds that have underground or sprawling root systems, not just the parts you touch on the surface.

In contrast, a product that kills only the tissue it contacts would be a contact herbicide—its effect is limited to where it touches, with no guaranteed movement to the rest of the plant. The idea of targeting only certain weed species speaks to selectivity, not whether the herbicide is systemic. And the notion of being destructive to all living organisms is inaccurate because herbicides are formulated to affect plants, not every organism in the environment.