Okay, let me rephrase this, since I have absolutely no clue where you live so that I could compare to the trees in your zone, weather and locale, I have no way to tell what may be in your area for the winds and rains and birds to have found these and transferred to your no trees in the garden area. There are a few other weeds it may be as well, as these weeds can live for decades in the soil, centuries even...