What does it mean for an element to be mobile or immobile in plants? Generally speaking, mobile elements are those that can be moved from older to newer tissue in the plant, while immobile ones cannot be. For example, calcium is incorporated into the cell wall, so it is immobile; it cannot be relocated later. Plants with a deficiency of mobile elements ( e.g. nitrogen) will exhibit damage to older tissues as the nutrients are moved to new growth. Conversely, plants lacking immobile elements ( e.g. calcium) will exhibit stunted new growth while the older tissues stay healthy. Some elements ( e.g. sulphur) fall somewhere between these two extremes. To illustrate this concept, here is a plant with nitrogen deficiency ( source ). Notice how the older leaves are dying while the newer leaves are relatively normal. Is there an official list of mobile and immobile elements? No. You will probably