What is a common characteristic of systemic herbicides?

Systemic herbicides are designed to be absorbed by the plant and then move throughout its tissues. Once inside, these herbicides translocate, meaning they spread throughout the plant to reach areas that may not have been directly sprayed. This characteristic allows systemic herbicides to effectively control not just the visible parts of the plant but also those hidden parts, like roots and shoots, which can be critical for ensuring that the entire plant is eliminated. This mode of action is particularly beneficial for dealing with perennial weeds that can regrow from underground structures if only a part of the plant is treated.

Other options are not accurate reflections of systemic herbicide behavior; for instance, systemic herbicides are indeed absorbed by the plant, and their effectiveness is not limited to just dry weather conditions. Therefore, the key trait of translocation following absorption is what sets systemic herbicides apart and makes them a powerful tool in pest and weed management.