system, published in Species Plantarum 1753 was a toughly milestone
in taxonomy, where the binomial nomenclature were introduced. He abandoned
the long descriptive names of classes and orders and two-word generic names.
Species Plantarum presented a complete list of the plant species then
known, ordered for the purpose of easy identification.
A plant's class was determined by its stamens (male organs), and its order
by its pistils (female organs). Even though only 11 of Linnaeus families are
in use to day, it was a solid ground for the coming taxonomy. The down side
by this was the groups seems "unnatural". For instance, Linnaeus's Class
Monoecia, Order Monadelphia included plants with separate male and female
"flowers" on the same plant (Monoecia) and with multiple male organs joined
onto one common base (Monadelphia). This order included conifers such as
pines, firs, and cypresses (the distinction between true flowers and conifer
cones was not clear), but also included a few true flowering plants, such as
the castor bean. "Plants" without obvious sex organs were classified in the
Class Cryptogamia, or "plants with a hidden marriage," which lumped together
the algae, lichens, fungi, mosses and other bryophytes, and ferns.
The system contained 24 classes. The first 13 are divided on their equal
long and separated male parts, the next two by uneven length, five with male
parts grown together with them selves or the female part, three classes with
single sex plants and one class with plants without flowers.
More systems and the history behind.