A new era dawned on botanical classification with the work of Antoine
Laurent de Jussieu (1748-1836). His uncle, Bernard de Jussieu, had
adopted the principles of Linnaeus's _Fragmenta_ in his arrangement of
the plants in the royal garden at the Trianon. At an early age Antoine
became botanical demonstrator in the Jardin des Plantes, and was thus
led to devote his time to the science of botany. Being called upon to
arrange the plants in the garden, he necessarily had to consider the
best method of doing so, and, following the lines already suggested by
his uncle, adopted a system founded in a certain degree on that of Ray,
in which he embraced all the discoveries in organography, adopted the
simplicity of the Linnean definitions, and displayed the natural
affinities of plants. His _Genera Plantarum_, begun in 1778, and finally
published in 1789, was an important advance, and formed the basis of all
natural classifications. One of the early supporters of this natural
method was Augustin Pyramus de Candolle (1778-1841), who in 1813
published his _Theorie elementaire de la botanique_, in which he showed
that the affinities of plants are to be sought by the comparative study
of the form and development of organs (morphology), not of their
functions (physiology). His _Prodromus Systematis Naturalis Regni
Vegetabilis_ was intended to embrace an arrangement and description of
all known plants. The work was continued after his death, by his son
Alphonse de Candolle, with the aid of other eminent botanists, and
embraces descriptions of the genera and species of the orders of
Dicotyledonous plants. The system followed by de Candolle is a
modification of that of Jussieu.

In arranging plants according to a natural method, we require to have a
thorough knowledge of structural and morphological botany, and hence we
find that the advances made in these departments have materially aided
the efforts of systematic botanists.

Robert Brown (1773-1858) was the first British botanist to support and
advocate the natural system of classification. The publication of his
_Prodromus Florae Novae Hollandiae_ (in 1810), according to the natural
method, led the way to the adoption of that method in the universities
and schools of Britain. In 1827 Brown announced his important discovery
of the distinction between Angiosperms and Gymnosperms, and the
philosophical character of his work led A. von Humboldt to refer to him
as "Botanicorum facile pri