The most left-hand colum of Table 2 indicates that at each of the three
levels considered there has been a mental method of storage, a textual method, a formal printed method using tables and/or graphs, and a computerised
method. Of these, the mental method is by far the oldest, with the
textual method also going back thousands of years. Use of tables and graphs
to summarise plant/environment relationships has come into prominence only in recent times, though tables may have existed for hundreds of years
in guides to gardeners and herbalists. Computer storage is of course very
recent by comparison.