Taxonomy of Flowering Plants - LECTURE NOTES
Hugh D. Wilson

The Rosidae

The Subclass Dilleniidae, includes 18 orders, 116 families and over 60,000 species.  The largest subclass with regard to number of families and comparable to the Asteridae with regard to species diversity.  As was the case with the Dilleniidae, about 75% of the species occur in five orders; in this case the Fabales (18,000), Myrtales (9,000), Euphorbiales (8,000), Rosales (6,600) and Sapindales (5,400).   Also, local Santalales - Rafflesiales (Phoradendron - Viscaceae).
 
 

A diverse set of flowering plant orders that, like the Dilleniidae, lacks a distinct set of key characters.  General trends or features of the Subclass include:

Cronquist: "In the last analysis, the Rosidae and Dilleniidae are kept apart as subclasses because each seems to constitute a natural group separately derived from the ancestral Magnoliidae, rather than because of any definitive distinguishing characters...it is conceptually more useful to hold the two as separate subclasses than to combine them into one or to abandon any attempt at organization of the Magnoliopsida into subclasses."  THEREFORE:  Focus here is on distinctive characters at the order and family level.
 
 

Our coverage of the Rosidae will include:

Rosales
     Crassulaceae
     Rosaceae
Fabales (Leguminosae)
    Mimosaceae
    Caesalpiniaceae
    Fabaceae
Myrtales
    Onagraceae
Euphorbiales
    Euphorbiaceae
Apiales
    Apiaceae (Umbelliferae)


Return to Lecture Notes, the Biology 301 homepage, the Asteridae, or the Dilleniidae