The
basal angiosperms are the first
flowering plantThe flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by a series of synapomorphies...
s to diverge from the ancestral angiosperm. In particular, the most
basalIn phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
angiosperms are the so-called
ANITA grade which is made up of
AmborellaAmborella is a genus of rare understory shrubs or small trees endemic to the island of New Caledonia. The genus consists of only a single species, Amborella trichopoda, and is the only member of the family Amborellaceae. Wood of Amborella lacks the vessels characteristic of most flowering plants...
(a single species of shrub from New Caledonia),
NymphaealesNymphaeales is an order of plants, which consists of water lilies and other aquatic plants.This order is considered to be a basal, or early diverging, group of angiosperms...
(water lilies, together with some other aquatic plants) and
AustrobaileyalesAustrobaileyales is the botanical name for an order of flowering plants, consisting of about 100 species of woody plants, perhaps the most famous of which is the spice star anise.- In different classifications :...
(woody aromatic plants including star anise). ANITA stands for the genera
Amborella,
Nymphaea,
Illicium,
Trimenia and
Austrobaileya.
The basal angiosperms are only a few hundred species, compared with hundreds of thousands of species of eudicots, monocots or magnoliids. They diverged from the ancestral angiosperm before the five groups comprising the mesangiosperms diverged from each other.
Phylogeny
The exact relationships between
AmborellaAmborella is a genus of rare understory shrubs or small trees endemic to the island of New Caledonia. The genus consists of only a single species, Amborella trichopoda, and is the only member of the family Amborellaceae. Wood of Amborella lacks the vessels characteristic of most flowering plants...
,
NymphaealesNymphaeales is an order of plants, which consists of water lilies and other aquatic plants.This order is considered to be a basal, or early diverging, group of angiosperms...
and
AustrobaileyalesAustrobaileyales is the botanical name for an order of flowering plants, consisting of about 100 species of woody plants, perhaps the most famous of which is the spice star anise.- In different classifications :...
are not yet clear. Although most studies show that
Amborella and Nymphaeales are more basal than Austrobaileyales, and all three are more basal than the mesangiosperms, there is significant molecular evidence in favor of two different trees, one in which
Amborella is sister to the rest of the angiosperms, and one in which a
cladeA clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
of
Amborella and Nymphaeales is in this position:
Older terms
Paleodicots (sometimes spelled "palaeodicots") is an informal name used by botanists (Spichiger & Savolainen 1997, Leitch et al. 1998) to refer to angiosperms which are not monocots or
eudicotsEudicots and Eudicotyledons are botanical terms introduced by Doyle & Hotton to refer to a monophyletic group of flowering plants that had been called tricolpates or non-Magnoliid dicots by previous authors...
.
The paleodicots correspond to
MagnoliidaeMagnoliids are a group of about 9,000 species of flowering plants, including magnolias, nutmeg, bay laurel, cinnamon, avocado, black pepper, and many others. They are characterized by trimerous flowers, pollen with one pore, and usually branching-veined leaves.-Classification:Traditionally,...
sensu Cronquist 1981 (minus Ranunculales and Papaverales) and to
MagnoliidaeMagnoliids are a group of about 9,000 species of flowering plants, including magnolias, nutmeg, bay laurel, cinnamon, avocado, black pepper, and many others. They are characterized by trimerous flowers, pollen with one pore, and usually branching-veined leaves.-Classification:Traditionally,...
sensu Takhtajan 1980 (Spichiger & Savolainen 1997). Some of the paleodicots share apparently plesiomorphic characters with monocots, e.g., scattered vascular bundles, trimerous flowers, and non-tricolpate
pollenPollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement from the stamens to the pistil of flowering plants or from the male cone to the...
.
The "paleodicots" are not a monophyletic group and the term has not been widely adopted. The
APG II systemThe APG II system of plant classification is the second, now obsolete, version of a modern, mostly molecular-based, system of plant taxonomy that was published in April 2003 by the Angiosperm Phylogeny Group. It was a revision of the first APG system, published in 1998, and was superseded in 2009...
does not recognize a group called "paleodicots" but assigns these early-diverging dicots to several orders and unplaced families:
AmborellaceaeAmborella is a genus of rare understory shrubs or small trees endemic to the island of New Caledonia. The genus consists of only a single species, Amborella trichopoda, and is the only member of the family Amborellaceae. Wood of Amborella lacks the vessels characteristic of most flowering plants...
,
NymphaeaceaeNymphaeaceae is a family of flowering plants. Members of this family are commonly called water lilies and live in freshwater areas in temperate and tropical climates around the world. The family contains eight genera. There are about 70 species of water lilies around the world. The genus...
(including
CabombaceaeCabombaceae is the botanical name of a family of flowering plants. The family has been recognised as distinct by at least some taxonomists and by APG III...
),
AustrobaileyalesAustrobaileyales is the botanical name for an order of flowering plants, consisting of about 100 species of woody plants, perhaps the most famous of which is the spice star anise.- In different classifications :...
, Ceratophyllales (not included among the "paleodicots" by Leitch et al. 1998),
ChloranthaceaeChloranthaceae is the botanical name of a family of flowering plants. The family consists of four genera, totalling several dozen species, of herbaceous or woody plants occurring in Southeast Asia, the Pacific, Madagascar, Central & South America, and the West Indies...
, and the magnoliid clade (orders
CanellalesCanellales is the botanical name for an order of flowering plants, one of the four orders of the magnoliids. It is defined to contain two families: Canellaceae and Winteraceae, which comprise 136 species of fragrant trees and shrubs...
,
PiperalesPiperales is a botanical name for an order of flowering plants. It necessarily includes the family Piperaceae but otherwise has been treated variously over time...
,
LauralesThe Laurales are an order of flowering plants. They are magnoliids, related to the Magnoliales.The order includes about 2500-2800 species from 85-90 genera, which comprise seven families of trees and shrubs. Most of the species are tropical and subtropical, though a few genera reach the temperate...
, and
MagnolialesMagnoliales is an order of flowering plants.-Classification:The Magnoliales includes six families:* Annonaceae...
). Subsequent research has added
HydatellaceaeHydatellaceae are small, aquatic flowering plants. The family includes the genus Trithuria, which has been recently re-defined to include the genus Hydatella. The family consists of about a dozen species. These tiny , relatively simple, aquatic plants occur in Australasia and India. The simple...
to the paleodicots.
The term
paleoherb is another older term for flowering plants which are neither eudicots nor monocots.