Seed of corn (Zea mays L., var. Texas 28) and cotton (Gossypium hirsutum L., var. Deltapine smooth leaf) were planted in sand and subsequently drenched with solutions of α,α,α trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin). The levels of herbicide used inhibited growth of roots and shoots in both crops, but cotton proved more tolerant than corn. The roots failed to elongate normally, but the lateral growth that continued gave the radicle a “club-shaped” appearance, especially in corn. Stained sections of the roots were mounted as permanent slides for study. The cells at the extreme tip of the treated roots were small and dense; many were multinucleate. Immediately behind this region, the cells were abnormally large, thin-walled, and aberrant. A disorganized type of nuclear division was evident. Cell plate and cell wall formation were apparently rare. Although we found no normal sequence of mitosis in cells of treated roots, all stages of mitosis were seen in the untreated roots.