LINNAEUSS NATURAL AND ARTIFICIAL ARRANGEMENTS OF PLANTS

Linnaeus's artificial and natural arrangements of plants are examined using a Spearman rank coefficient (which is explained) on his presenta tions of his own and others' arrangements in the Classes plantarum and elsewhere. There is little alteration in his successive artificial ar rangements. In contrast, between 1751 and 1764 his natural arrangement s changed considerably, partly in the sequences of genera within order s but mostly by rearrangement of the orders. Comparison with Cesalpino 's and Ray's natural arrangements, using the longest-recognized natura l groups as signposts, suggests that Linnaeus in his latest natural ar rangement (1764) approximated more closely to Ray's. Examination of Li nnaeus's successive treatments of certain groups (palms, Zingiberaceae , Hydrocharis-Stratiotes-Vallisneria) and of Giseke's exposition of Li nnaeus's lectures on natural groups (1792) shows that Linnaeus was muc h influenced by habitus and vegetative characters as well as those of the fructification. He recognized orders consisting of a chain of gene ra linked successively by overall affinity and without any single diag nostic character. Where possible, he preferred characters of the fruct ification and his 'secret' consulting of the habitus is explained as s econdary to such characters. It is suggested that in his latest arrang ement he approximated more to a scala naturae, as he probably did in z oology about the same time. Within his artificial arrangements Linnaeu s kept to sequences of genera as natural as possible. He realized that some groups in his natural arrangements were still artificial, and hi s aphorism that all genera and species are natural, classes and orders part natural and part artificial, refers to his and others' practice until the natural system could be completed. It is not a statement of the essential natures of these ranks. Linnaeus's distinction in practi ce between natural and artificial arrangements was less clear-cut than Sachs believed. Linnaeus's rejection of the ancient tree/herb divisio n was empirical, not a reasoned repudiation of an a priori grouping. T he tree/herb division could be upheld in his day as obviously natural, not merely accepted on authority.