The basal angiosperms are the

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants t ...

s which diverged from the lineage leading to most flowering plants. In particular, the most basal angiosperms were called the ANITA grade, which is made up of ''

Amborella ''Amborella'' is a monotypic genus of understory shrubs or small trees Endemism, endemic to the main island, Grande Terre (New Caledonia), Grande Terre, of New Caledonia in the southwest Pacific Ocean. The genus is the only member of the family ...

'' (a single species of shrub from New Caledonia), Nymphaeales (water lilies, together with some other aquatic plants) and Austrobaileyales (woody aromatic plants including star anise). ''ANITA'' stands for ''Amborella'', ''N''ymphaeales, ''I''lliciales, ''T''rimeniaceae, and '' Austrobaileya''. Some authors have shortened this to ''ANA''-grade for the three orders, ''A''mborellales, ''N''ymphaeales, and ''A''ustrobaileyales, since the order Iliciales was reduced to the family Illiciaceae and placed, along with the family Trimeniaceae, within the Austrobaileyales. The basal angiosperms are only a few hundred species, compared with hundreds of thousands of species of

eudicots The eudicots, Eudicotidae, or eudicotyledons are a clade of flowering plants mainly characterized by having two seed leaves upon germination. The term derives from Dicotyledons. Traditionally they were called tricolpates or non-magnoliid dicot ...

, monocots, and

magnoliids Magnoliids (or Magnoliidae or Magnolianae) are a clade of flowering plants. With more than 10,000 species, including magnolias, nutmeg, bay laurel, cinnamon, avocado, black pepper, tulip tree and many others, it is the third-largest group of a ...

. They diverged from the ancestral angiosperm lineage before the five groups comprising the mesangiosperms diverged from each other.

Phylogeny

The exact relationships between ''

'', Nymphaeales and Austrobaileyales 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

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English ter ...

of ''Amborella'' and Nymphaeales is in this position. A 2014 paper says that it presents "the most convincing evidence to date that ''Amborella'' plus Nymphaeales together represent the earliest diverging lineage of extant angiosperms". A number of other studies identify ''Amborella'' the most basal of all angiosperms.

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

monocot Monocotyledons (), commonly referred to as monocots, (Lilianae '' sensu'' Chase & Reveal) are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one embryonic leaf, or cotyledon. They constitute one ...

s or

. The paleodicots correspond to Magnoliidae sensu Cronquist 1981 (minus Ranunculales and Papaverales) and to Magnoliidae 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

pollen Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametop ...

. The "paleodicots" are not a monophyletic group and the term has not been widely adopted. The APG II system does not recognize a group called "paleodicots" but assigns these early-diverging dicots to several orders and unplaced families: Amborellaceae,

Nymphaeaceae Nymphaeaceae () is a family of flowering plants, commonly called water lilies. They live as rhizomatous aquatic herbs in temperate and tropical climates around the world. The family contains nine genera with about 70 known species. Water ...

(including Cabombaceae), Austrobaileyales, Ceratophyllales (not included among the "paleodicots" by Leitch et al. 1998), Chloranthaceae, and the

magnoliid Magnoliids (or Magnoliidae or Magnolianae) are a clade of flowering plants. With more than 10,000 species, including magnolias, nutmeg, bay laurel, cinnamon, avocado, black pepper, tulip tree and many others, it is the third-largest group of a ...

clade (orders Canellales, Piperales,

Laurales The 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 Magnoliales). Subsequent research has added Hydatellaceae to the paleodicots. The term ''paleoherb'' is another older term for flowering plants which are neither eudicots nor monocots.

References

External links

tolweb.org
{{Angiosperm orders Angiosperms