Plants need to absorb certain minerals from the soil in adequate quantities for normal growth and development. A. Some plants are able to accumulate extremely high levels of certain minerals and thus can be used to clean up soils contaminated with toxic levels of these minerals. B. Though beneficial in lower levels, high levels of salts, other minerals, and heavy metals can be harmful to plants. C. When plants do not absorb sufficient amounts of essential minerals, characteristic abnormalities result. D. Because high concentrations of sodium chloride and other salts limit growth in most plants, much research has been done in an effort to develop salt-tolerant agricultural crops. E. Some plants can tolerate comparatively low levels of certain minerals, but such plants are of little use for recycling nutrients back into depleted soils. F. Mineral deficiencies in many plants can be cured by misting their roots with a nutrient solution or by transferring the plants to a soilless nutrient solution.