The auricles are absent. The ligule is membraneous but prominent even though it is acute. Some weed seeds can persist for decades in the soil and all are immune to herbicides. The rest are left dormant, waiting for a future growing seasons or good, opportunist germination conditions. Largely, herbicides affect only seeds that germinate.
Most dormant seeds remain unharmed.
A more profitable action is to use existing moist conditions through the spring or irrigation to stimulate germination and then to eliminate the weed seedlings with current herbicides. Some nitrogen compounds, growth regulators, anesthetics and a few herbicides can stimulate weed seed germination. The most successful has been the growth regulator ethylene. Ethylene can even stimulate the germination of hard to germinate parasitic weeds such as witchweed, which normally requires a chemical release by the roots of other plants that serve as hosts. Stimulants for breaking weed seed dormancy should be able to break the dormancy in seeds that normally require light to germinate, too, among the many other diverse weed seed characteristics.