This research led to the discovery that boron (B) deficient plants contain little or no ascorbate (Vitamin C) in root tips, which results in extremely slow growth rates. Under B deficiency, root tips of squash and alfalfa contained 10 times more iron and 1.5 times more copper than if B were sufficient, with much of the iron in the ferric (Fe3+) form and accumulated in the root cell wall. The low ascorbate caused by B deficiency may prevent the reduction of the iron to the ferrous (Fe2+) form that plants can use. While this does not appear to cause an iron deficiency concern, it does suggest that ferric iron may precipitate phosphorus and form a type of iron plaque that could inhibit root uptake efficiency in general. Boron deficiency can also result in lower root potassium and magnesium contents. Under conditions of aluminum toxicity, phosphorus, iron, and B accumulate in root tips. Aluminum toxicity, just as with B deficiency, causes a reduction in ascorbate levels in root tips.