Probably it was the critical study of the works of the Bauhins that led Morison to frame a system of classification of his own.
The third and last treatise is the Dialogus: a dialogue between himself, as Botanographus Regius, King's Botanist, and a Fellow of the Royal Society, on the theme of classification. Here again Morison asserts the superiority of his own method: "Methodum me observasse fateor: estque omnium quae unquam adhuc fuerunt exhibitae, praestantissima et certissima quippe a natura data." But he still fails to give any definite account of it: all that he says amounts merely Paolo Bocconeato this, that the "nota generica" is not to be sought in the properties of a plant, nor in the shape of its leaves, as had been suggested by earlier writers, but in the fructification, that is, in the flower and fruit (essentiam plantarum desumendam…a florum forma et seminum conformatione).
The mention of a system of classification based on the form of the leaf evoked from Botanographus a pointed allusion to a book recently published by a Fellow of the Royal Society in which such a classification had been used, with the following severe comment: "Ego tantum confusum Chaos: illic, de plantis legi, nec quicquam didici, ut monstrabo tibi et lapsus et confusionem, alias." The book so criticised was the encyclopaedic work edited by Dr John Wilkins, Bishop of Chester, and published by the Royal Society in 1668, entitled, "An Essay towards a Real Character and a Philosophical Language" to which John Ray had contributed the botanical article 'Tables of Plants.' This criticism was the beginning of the unfriendly relations between Morison and Ray, of which some further account will be given subsequently.
Another point of interest in the Dialogus is the definite assertion (p. 488) that Ferns are 'perfect' plants, having flower and seed (quia habent flores, qui fugiunt quasi obtutum, et semina quasi pulvisculum in dorso alarum), an assertion which was repeated with even greater emphasis in Morison's preface to his edition of Boccone's Icones et Descriptions Rariorum Plantarum etc. (Oxon. 1674), in opposition to the views of earlier writers, Cesalpino in particular. Cesalpino had, it is true, said of the group in which he had placed the Ferns and other Cryptogams
