| Abstract: | Linnaeus's artificial and natural arrangements of plants are examined using a Spearman rank coefficient (which is explained) on his presentations of his own and others' arrangements in the Classes plantarum and elsewhere. There is little alteration in his successive artificial arrangements. In contrast, between 1751 and 1764 his natural arrangements changed considerably, partly in the sequences of genera within orders but mostly by rearrangement of the orders. Comparison with Cesalpino's and Ray's natural arrangements, using the longest-recognized natural groups as signposts, suggests that Linnaeus in his latest natural arrangement (1764) approximated more closely to Ray's. Examination of Linnaeus's successive treatments of certain groups (palms, Zingiberaceae, Hydrocharis-Stratiotes-Vallisneria) and of Giseke's exposition of Linnaeus's lectures on natural groups (1792) shows that Linnaeus was much influenced by habitus and vegetative characters as well as those of the fructification. He recognized orders consisting of a chain of genera linked successively by overall affinity and without any single diagnostic character. Where possible, he preferred characters of the fructification and his ‘secret’ consulting of the habitus is explained as secondary to such characters. It is suggested that in his latest arrangement he approximated more to a scala naturae, as he probably did in zoology about the same time. Within his artificial arrangements Linnaeus kept to sequences of genera as natural as possible. He realized that some groups in his natural arrangements were still artificial, and his 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 practice between natural and artificial arrangements was less clear-cut than Sachs believed. Linnaeus's rejection of the ancient tree/herb division was empirical, not a reasoned repudiation of an a priori grouping. The tree/herb division could be upheld in his day as obviously natural, not merely accepted on authority. |
