Taxonomy of Flowering Plants - LECTURE NOTES
Hugh D. Wilson

The Magnoliidae

Subclass Magnoliidae includes 8 orders, 39 families and about 11,000 species.  Families included by Cronquist in this subclass show a tendency for retention of primitive features and, regardless of the classification system, most are placed at the base of the dicot lineage.


The most archaic element of the Subclass, families of the largest Order, the Magnoliales tend to express the highest level primitive features, as originally defined by Charles Bessey (photo) in his description what the first angiosperm might have been like:

1.  A woody, dicot-like plant - maybe arborescent, but more likely a fruticose, shrubby plant of seasonally dry, sub-tropical habitats

2.  LEAVES were simple, persisent (evergreen), entire, alternate, pinnately veined, glabrous, and probably stipulate

3.  FLOWERS were solitary, terminal, perfect, actinomorphic, with no connation or adnation.  The numerous floral parts of this flower were spirally arranged on an elongate floral axis.

    PERIANTH:  many parted with poor differentiation between appendages of the corolla and calyx (TEPALS)

    ANDROECIUM:  many stamens that were broad and laminar (no distinct filament)

    GYNOECIUM:  apocarpous and producing a FOLLICLE

The flowers were probably adapted for insect pollination (entomophilous), most likely beetles, as opposed to wind pollination (anemophilous).

Our survey of this basal group will start with the Magnoliales and touch on representatives of other Orders of the Subclass.  The alignment and sequence of Orders depicted above represents Cronquist's placement relative to the Magnoliales in terms of structural specializations.  His terminal group - the Papaverales - is made up of herbaceous, syncarpous plants.  Our coverage of the Subclass Magnoliidae will include:

Magnoliales
    Winteraceae
    Magnoliaceae
Ranunculales
    Ranunculaceae
Papaverales
    Papaveraceae
Laurales
    Lauraceae
Nymphaeales
    Nymphaeaceae

See Wikipedia page for a comparative view of different taxonomic treatments of this general 'archaic' group.


Return to Lecture Notes, the Biology 301 homepage, the Hamamelidae or the Origins/Classification