Question

The number of species classified in ‘Species Plantarum’ is
A. 3800
B. 4000
C. 5900
D. 6000

Answer 1

Hint: ‘Species Plantarum’ is a book by Carl Linnaeus.
It was originally published in 1753, which lists every species of plant known at that time, classified into genera.

Complete answer: Linnaeus introduced the binomial system of the naming of plants in his book.
This system forms the basis of modern plant taxonomy.
Linnaeus described 6,000 species of plants and assigned each plant a genus name and a species name, the genus representing a group of plants, the species designating specific individuals within a given genus.

So, the correct answer is “Option D”.

Additional Information: Linnaeus estimated that there were not more than 10,000 plant species in existence; but now it is thought to be around 400,000 species of flowering plants alone.
Species Plantarum was chosen as the "starting point" for the nomenclature of most plants but the nomenclature of some non-vascular plants and all fungi use later starting points that are modern.
In his book, the species were arranged in around a thousand genera, which were grouped into 24 classes, according to Linnaeus' sexual system of classification.
There are no descriptions of the genera in Species Plantarum; these are supplied in the companion volume Genera Plantarum ("the genera of plants").

Note: Linnaeus is known as ‘Father of taxonomy’.
Linnaeus' sexual system is now acknowledged to be an artificial system, rather than one which accurately reflects shared ancestry but the system's simplicity made it easier for non-specialists to rapidly find the correct class, being based on simple counts of floral parts such as stigmas and stamens, and without it, the scientists would have spared lots of time.