Asterales

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Asterales
Sunflower
, Helianthus annuus
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Clade:
Campanulids
Order: Asterales
Link[1]
Families

Asterales (

florets, and ten families related to the Asteraceae.[3] While asterids in general are characterized by fused petals, composite flowers consisting of many florets create the false appearance of separate petals (as found in the rosids
).

The order is cosmopolitan (plants found throughout most of the world including desert and frigid zones), and includes mostly herbaceous species, although a small number of trees (such as the Lobelia deckenii, the giant lobelia, and Dendrosenecio, giant groundsels) and shrubs are also present.

Asterales are organisms that seem to have evolved from one common

Synapomorphies (a character that is shared by two or more groups through evolutionary development) include the presence in the plants of oligosaccharide inulin, a nutrient storage molecule used instead of starch; and unique stamen morphology. The stamens are usually found around the style, either aggregated densely or fused into a tube, probably an adaptation in association with the plunger (brush; or secondary) pollination
that is common among the families of the order, wherein pollen is collected and stored on the length of the pistil.

Taxonomy

The name and order Asterales is botanically venerable, dating back to at least 1926 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.[4]

Campanulid clade 
 (similar to Euasterids II in APG II)

 Aquifoliales

 Bruniales

 

Paracryphiales

 Dipsacales

 Apiales

 

Escalloniales

 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 are

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.[4] 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.[5]

Biogeography

The core Asterales are Stylidiaceae (six genera), APA clade (Alseuosmiaceae, Phellinaceae and Argophyllaceae, together seven genera), MGCA clade (Menyanthaceae, Goodeniaceae, Calyceraceae, in total twenty genera), and Asteraceae (about sixteen hundred genera). Other Asterales are Rousseaceae (four genera), Campanulaceae (eighty-four genera) and Pentaphragmataceae (one genus).

All Asterales families are represented in the Southern Hemisphere; however, Asteraceae and Campanulaceae are cosmopolitan and Menyanthaceae nearly so.[6]

Uses

The Asterales, by dint of being a super-set of the family Asteraceae, include some species grown for food, including the

sunflower (Helianthus annuus), lettuce (Lactuca sativa) and chicory (Cichorium).[7]
Many are also used as spices and traditional medicines.

Asterales are common plants and have many known uses. For example,

Wormwood, derived from a genus that includes the sagebrush, is used as a source of flavoring for absinthe, a bitter classical liquor of European origin.[9]

References

  1. hdl:10654/18083
    .
  2. ISBN 978-0-88192-627-9
    . Retrieved 14 April 2020.
  3. ^ Kubitzki, K. (1990). The Families and Genera of Vascular Plants: Flowering Plants, Eudicots: Asterales. Springer. Retrieved 14 April 2020.
  4. ^ a b "Angiosperm Phylogeny Website". Mobot.org. Retrieved 12 June 2012.
  5. PMID 9256457
    .
  6. ISBN 978-3-9501754-3-1. Archived
    (PDF) from the original on 9 October 2022. Retrieved 14 April 2020.
  7. ^ "A Brief Overview of the Compositae, Lettuce and Sunflower". 28 October 2015. Retrieved 14 April 2020.
  8. ISBN 978-1-59339-492-9
    . Retrieved 14 April 2020.
  9. ^ Wondrich, David (5 August 2008). "The Five Best Bottles of Absinthe". Esquire.

Further reading

External links

Wikimedia Commons has media related to Asterales (category).
Wikispecies has information related to Asterales.
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