History of plant systematics

The professionalization of botany in the 18th and 19th century marked a shift toward more holistic classification methods, eventually based on evolutionary relationships.

[1] He did not articulate a formal classification scheme, but relied on the common groupings of folk taxonomy combined with growth form: tree shrub; undershrub; or herb.

The Byzantine emperor Constantine VII sent a copy of Dioscorides' pharmacopeia to the Umayyad Caliph Abd al-Rahman III who ruled Córdoba in the 9th century, and also sent a monk named Nicolas to translate the book into Arabic.

Ray, who listed over 18,000 plant species in his works, is credited with establishing the monocot/dicot division and some of his groups—mustards, mints, legumes and grasses—stand today (though under modern family names).

[citation needed] Although meticulous, the classification of Linnaeus served merely as an identification manual; it was based on phenetics and did not regard evolutionary relationships among species.

[1] It assumed that plant species were given by God and that what remained for humans was to recognise them and use them (a Christian reformulation of the scala naturae or Great Chain of Being).

To this was added the interest in plant anatomy, aided by the use of the light microscope and the rise of chemistry, allowing the analysis of secondary metabolites.

For the first time relatedness could be measured in real terms, namely similarity of the molecules comprising the genetic code.