Angiosperms: Major Groups
In the good old days, there were two major groups of angiosperms, dicots and monocots. It was thought
that the monocots were derived from within a large basal group called something like magnoliids. Today
things are a little more complex. Angiosperms have four major groups: basal angiosperms, magnoliidids,
monocots, and eudicots. All but the basal angiosperms are thought to be monophyletic. The old
magnoliids were, more or less, the basal angiosperms plus the new magnoliids.
It helps to be able to place plants into one of the major groups – and then start keying. The table below
should enable you to decide in which of the four groups your plants belong. It is intended for use in the
Intermountain Region. A few greenhouse and garden species have been considered in its preparation.
Links are to existing PDF keys.
Leaves
Basal Angiosperms
Alternate, simple,
petiolate, blades ovate to
triangular, smooth-edged,
often with cordate base.
Inflorescence Solitary or of many, small
flowers spirally arranged.
Habit (IMR
taxa)
Woody shrubs or vines or
aquatic herbs
Perianth
Tepals not united; gradual
change from outer tepals
to inner tepals to stamens;
indefinite number
Androecium
Indefinite number, spirally
arranged, laminar filament
Gynoecium
Separate or united, of
several carpels; ovary
superior
Magnoliids
Alternate, simple,
petiolate, blades
usually ovate,
sometimes lobed,
smooth-edged.
Flowers often
solitary relatively
large
Woody or
herbaceous
Tepals not united;
gradual change
from outer tepals
to inner tepals to
stamens;
indefinite number
Indefinite
number, spirally
arranged
Indefinite
number, spirally
arranged,
separate; ovary
superior
Monocots
Linkage between
secondary veins
often not evident
Dicots
Usually reticulate
venation visible
Varied
Varied
Mostly
herbaceous,
never with
secondary
vascular cambium
Multiples of 3,
free or united,
usually calyx and
corolla distinct, in
whorls
Varied
Multiples of 3 (or
only 1 or 2), in
whorls if 2 or
more times 3
1-2 or multiples
of 3, separate or
united, superior
or inferior
Usually Multiples
of 4 or 5, free or
united, usually
calyx and corolla
distinct, in whorls
Multiples of 4 or
5 (or 1 or2)
sometimes many,
whorls if 2 or
more times 4 or 5
1-many or
multiples of 3,
separate or
united, superior
or inferior
Families
accessible to
USU-Logan
students
(native)
Amborellaceae
Nymphaeaceae
Saururaceae
Piperaceae
Aristolochiaceae
Magnoliaceae
Lauraceae
Too many to list
Too many to list
Basal angiosperms
This is a polyphyletic group of families that are ancestral to all other angiosperms. Only oneof the seven
families is available on the Logan campus of USU. It is the Nymphaeaceae which is represented by the
native genus Nuphar.
Magnoliidae
This subclass is represented primarily by cultivated species within the IMR but there is a native member
of the Saururaceae present. The families represented by cultivated genera that can survive outside are
Magnoliaceae (Magnolia, Liriodendron), Lauraceae (Persea, Laurus). Two families that are grown in the
greenhouse at USU (and probably on other campuses too) are Aristolochiaceae, Piperaceae and
Degeneriaceae.