Editing Asterales (section)

== Taxonomy ==
The name and order Asterales is botanically venerable, dating back to at least 1926 in the [[Hutchinson system|Hutchinson system of plant taxonomy]] when it contained only five families, of which only two are retained in the [[APG III system|APG III]] classification. Under the [[Cronquist system]] of taxonomic classification of flowering plants, [[Asteraceae]] was the only family in the group, but newer systems (such as [[APG II system|APG II]] and APG III) have expanded it to 11. In the classification system of [[Rolf Dahlgren]] the Asterales were in the [[superorder]] Asteriflorae (also called Asteranae).

The order '''Asterales''' currently includes 11 families, the largest of which are the Asteraceae, with about 25,000 species, and the [[Campanulaceae]] (bellflowers), with about 2,000 species. The remaining families count together for less than 1500 species. The two large families are cosmopolitan, with many of their species found in the Northern Hemisphere, and the smaller families are usually confined to Australia and the adjacent areas, or sometimes South America.

Only the Asteraceae have composite flower heads; the other families do not, but share other characteristics such as storage of inulin that define the 11 families as more closely related to each other than to other plant families or orders such as the [[rosids]].

The phylogenetic tree according to APG III for the Campanulid clade is as below.<ref name=apweb>{{cite web|url=http://www.mobot.org/mobot/research/apweb/ |title=Angiosperm Phylogeny Website |publisher=Mobot.org |access-date=2012-06-12}}</ref>

{{Clade
|label1=[[Campanulids|Campanulid clade]] (similar to '''Euasterids II''' in APG II)
|1={{Clade
              |1=[[Aquifoliales]]
              |2={{Clade
                 |1={{Clade
                    |1=[[Bruniales]]
                    |2={{Clade
                       |1={{Clade
                          |1=[[Paracryphiales]]
                          |2=[[Dipsacales]]
                          }}
                       |2=[[Apiales]]
                       }}
                    }}
                 |2=[[Escalloniales]]
                 |3='''Asterales'''
                 }}
              }}
}}

=== Phylogeny ===
Although most extant species of Asteraceae are herbaceous, the examination of the basal members in the family suggests that the common ancestor of the family was an arborescent plant, a tree or shrub, perhaps adapted to dry conditions, radiating from South America. Less can be said about the Asterales themselves with certainty, although since several families in Asterales contain trees, the ancestral member is most likely to have been a tree or shrub.

Because all clades are represented in the Southern Hemisphere but many not in the Northern Hemisphere, it is natural to conjecture that there is a common southern origin to them. Asterales belong to [[angiosperms]] or flowering plants, a clade that appeared about 140 million years ago.{{Citation needed|date=September 2024|reason=Different sources estimate different dates of the origin of angiosperms}} The Asterales order probably originated in the [[Cretaceous]] (145 – 66 [[Mya (unit)#Symbols y and yr|Mya]]) on the supercontinent [[Gondwana]] which broke up from 184 – 80 Mya, forming the area that is now Australia, South America, Africa, India and Antarctica.

Asterales contain about 14% of [[eudicot]] diversity. From an analysis of relationships and diversities within the Asterales and with their superorders, estimates of the age of the beginning of the Asterales have been made, which range from 116 Mya to 82Mya.<ref name="apweb" /> However few fossils have been found, of the [[Menyanthaceae]]-Asteraceae clade in the [[Oligocene]], about 29 Mya.

Fossil evidence of the Asterales is rare and belongs to rather recent epochs, so the precise estimation of the order's age is quite difficult. An Oligocene (34 – 23 Mya) pollen is known for Asteraceae and [[Goodeniaceae]], and seeds from Oligocene and [[Miocene]] (23 – 5.3 Mya) are known for Menyanthaceae and Campanulaceae respectively.<ref>{{cite journal |last1=Bremer |first1=K. |last2=Gustafsson |first2=M. H. G. |year=1997 |title=East Gondwana ancestry of the sunflower alliance of families |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=94 |issue=17 |pages=9188–9190 |bibcode=1997PNAS...94.9188B |doi=10.1073/pnas.94.17.9188 |pmc=23106 |pmid=9256457 |doi-access=free}}</ref> According to [[molecular clock]] calculations, the lineage that led to Asterales split from other plants about 112 million years ago<ref>{{Cite journal|last1=Bremer|first1=K.|last2=Friis|first2=E. M.|last3=Bremer|first3=B.|date=2004|title=Molecular phylogenetic dating of asterid flowering plants shows early Cretaceous diversification|journal=Systematic Biology|volume=53|issue=3|pages=496–505|issn=1063-5157|pmid=15503676|doi=10.1080/10635150490445913|doi-access=free}}</ref> or 94 million years ago.<ref name="magallon2009">{{citation |author1=Susana Magallón  |author2=Amanda Castillo  |name-list-style=amp | year = 2009 | title = Angiosperm diversification through time | journal = American Journal of Botany | volume = 96 | issue = 1 | pages = 349–365 | doi = 10.3732/ajb.0800060 | pmid = 21628193 }}</ref>