Asterales

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Asterales
A sunflower.jpg
Sunflower, Helianthus annuus
Scientific classification Red Pencil Icon.png
Domain: Eukaryota
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Clade: Campanulids
Order: Asterales
Link [1]
Families

Asterales /æstəˈrlz/ [2] is an order of dicotyledonous flowering plants that includes the large family Asteraceae (or Compositae) known for composite flowers made of florets, and ten families related to the Asteraceae. [3]

Contents

The order is a cosmopolite (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 giant Lobelia and the giant Senecio) and shrubs are also present.

Asterales are organisms that seem to have evolved from one common ancestor. Asterales share characteristics on morphological and biochemical levels. 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 Hutchinson system of plant taxonomy when it contained only five families, of which only two are retained in the 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 and APG III) have expanded it to 11. In the classification system of 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. [4]

Campanulid clade   (similar to Euasterids II in APG II)

  Aquifoliales

  Bruniales

  Paracryphiales

  Dipsacales

  Apiales

  Escalloniales

 Asterales

Biogeography

The core Asterales are Stylidiaceae (six genera), APA clade (Alseuosmiaceae, Phellinaceae and Argophyllaceae, together 7 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. [5]

Evolution

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 angiosperms, flowering plants that appeared about 140 million years ago. The Asterales order probably originated in the Cretaceous (145 – 66 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. [6]

Economic importance

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, pyrethrum (derived from Old World members of the genus Chrysanthemum) is a natural insecticide with minimal environmental impact. [8] 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]

Related Research Articles

Asteraceae Family of flowering plants

Asteraceae or Compositae, is a very large and widespread family of flowering plants (Angiospermae).

Flowering plant The clade of seed plants that produce flowers

The flowering plants, also known as Angiospermae, or Magnoliophyta, are the most diverse group of land plants, with 64 orders, 416 families, approximately 13,000 known genera and 300,000 known species. Like gymnosperms, angiosperms are seed-producing plants. They are distinguished from gymnosperms by characteristics including flowers, endosperm within their seeds, and the production of fruits that contain the seeds. Etymologically, angiosperm means a plant that produces seeds within an enclosure; in other words, a fruiting plant. The term comes from the Greek words angeion and sperma ("seed").

Malpighiales Eudicot order of flowering plants

The Malpighiales comprise one of the largest orders of flowering plants, containing about 36 families and more than 16,000 species, about 7.8% of the eudicots. The order is very diverse, containing plants as different as the willow, violet, poinsettia, manchineel, rafflesia and coca plant, and are hard to recognize except with molecular phylogenetic evidence. It is not part of any of the classification systems based only on plant morphology. Molecular clock calculations estimate the origin of stem group Malpighiales at around 100 million years ago (Mya) and the origin of crown group Malpighiales at about 90 Mya.

Rosales Order of flowering plants

Rosales is an order of flowering plants. It is sister to a clade consisting of Fagales and Cucurbitales. It contains about 7,700 species, distributed into about 260 genera. Rosales comprise nine families, the type family being the rose family, Rosaceae. The largest of these families are Rosaceae (90/2500) and Urticaceae (54/2600). The order Rosales is divided into three clades that have never been assigned a taxonomic rank. The basal clade consists of the family Rosaceae; another clade consists of four families, including Rhamnaceae; and the third clade consists of the four urticalean families.

Solanales Order of dicot flowering plants

The Solanales are an order of flowering plants, included in the asterid group of dicotyledons. Some older sources used the name Polemoniales for this order.

Dicotyledon Historical grouping of flowering plants

The dicotyledons, also known as dicots, are one of the two groups into which all the flowering plants or angiosperms were formerly divided. The name refers to one of the typical characteristics of the group, namely that the seed has two embryonic leaves or cotyledons. There are around 200,000 species within this group. The other group of flowering plants were called monocotyledons or monocots, typically having one cotyledon. Historically, these two groups formed the two divisions of the flowering plants.

Campanulales

Campanulales is a valid botanic name for a plant order. It was used in the Cronquist system as an order within the subclass Asteridae in the class Magnoliopsida flowering plants. As then circumscribed it included the families:

Berberidopsidales

Berberidopsidales is an order of Southern Hemisphere woody flowering plants. The name is newly accepted in the APG III system of plant taxonomy. APG II system, of 2003, mentions the possibility of recognizing the order, as comprising the families Berberidopsidaceae and Aextoxicaceae. However, APG II left the families unplaced as to order, assigning them to the clade core eudicots. The APG III system of 2009 formally recognized the order.

Buxales Order of eudicot flowering plants

The Buxales are a small order of eudicot flowering plants, recognized by the APG IV system of 2016. The order includes the family Buxaceae; the families Didymelaceae and Haptanthaceae may also be recognized or may be included in the Buxaceae. Many members of the order are evergreen shrubs or trees, although some are herbaceous perennials. They have separate "male" (staminate) and "female" (carpellate) flowers, mostly on the same plant. Some species are of economic importance either for the wood they produce or as ornamental plants.

Hamamelidaceae Witch-hazel family, of shrubs and small trees, in the order Saxifragales

Hamamelidaceae, commonly referred to as the witch-hazel family, is a family of flowering plants in the order Saxifragales. The clade consists of shrubs and small trees positioned within the woody clade of the core Saxifragales. An earlier system, the Cronquist system, recognized Hamamelidaceae in the Hamamelidales order.

Pandanales

Pandanales, the pandans or screw-pines, is an order of flowering plants placed in the monocot clade in the Angiosperm Phylogeny Group and Angiosperm Phylogeny Web systems. Within the monocots Pandanales are grouped in the lilioid monocots where they are in a sister group relationship with the Dioscoreales. Historically the order has consisted of a number of different families in different systems but modern classification of the order is based primarily on molecular phylogenetics despite diverse morphology which previously placed many of the families in other groupings based on apparent similarity. Members of the order have a subtropical distribution and includes trees, shrubs, and vines as well as herbaceous plants. The order consists of 5 families, 36 genera and about 1,610 species.

Campanulaceae Family of flowering plants comprising bellflowers

The family Campanulaceae, of the order Asterales, contains nearly 2400 species in 84 genera of herbaceous plants, shrubs, and rarely small trees, often with milky sap. Among them are several familiar garden plants belonging to the genera Campanula (bellflower), Lobelia, and Platycodon (balloonflower). Campanula rapunculus and Codonopsis lanceolata are eaten as vegetables. Lobelia inflata, L. siphilitica and L. tupa and others have been used as medicinal plants. Campanula rapunculoides may be a troublesome weed, particularly in gardens, while Legousia spp. may occur in arable fields.

Menyanthaceae

Menyanthaceae is a family of aquatic and wetland plants in the order Asterales. There are approximately 60-70 species in six genera distributed worldwide. The simple or compound leaves arise alternately from a creeping rhizome. In the submersed aquatic genus Nymphoides, leaves are floating and support a lax, umbellate or racemose inflorescence. In other genera the inflorescence is erect and consists of one to many flowers. The sympetalous, insect-pollinated flowers are five-parted and either yellow or white. The petals are ciliate or adorned with lateral wings. Fruit type is a capsule.

Berberidaceae

The Berberidaceae are a family of 18 genera of flowering plants commonly called the barberry family. This family is in the order Ranunculales. The family contains about 700 known species, of which the majority are in Berberis. The species include trees, shrubs and perennial herbaceous plants.

Eudicots Clade of flowering plants

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.

The APG system of plant classification is the first version of a modern, mostly molecular-based, system of plant taxonomy. Published in 1998 by the Angiosperm Phylogeny Group, it was replaced by the improved APG II in 2003, APG III system in 2009 and APG IV system in 2016.

The Kubitzki system is a system of plant taxonomy devised by Klaus Kubitzki, and is the product of an ongoing survey of vascular plants, entitled The Families and Genera of Vascular Plants, and extending to 15 volumes in 2018. The survey, in the form of an encyclopedia, is important as a comprehensive, multivolume treatment of the vascular plants, with keys to and descriptions of all families and genera, mostly by specialists in those groups. The Kubitzki system served as the basis for classification in Mabberley's Plant-Book, a dictionary of the vascular plants. Mabberley states, in his Introduction on page xi of the 2008 edition, that the Kubitzki system "has remained the standard to which other literature is compared".

Escalloniaceae

Escalloniaceae is a family of flowering plants consisting of about 130 species in seven genera. In the APG II system it is one of eight families in the euasterids II clade (campanulids) that are unplaced as to order. More recent research has provided evidence that two of those families, Eremosynaceae and Tribelaceae, arose from within Escalloniaceae; the Angiosperm Phylogeny Website therefore merges these two families into Escalloniaceae, and also places the family alone in order Escalloniales.

Goodeniaceae

Goodeniaceae is a family of flowering plants in the order Asterales. It contains about 404 species in twelve genera. The family is distributed mostly in Australia, except for the genus Scaevola, which is pantropical. Its species are found across most of Australia, being especially common in arid and semi-arid climates.

The APG III system of flowering plant classification is the third version of a modern, mostly molecular-based, system of plant taxonomy being developed by the Angiosperm Phylogeny Group (APG). Published in 2009, it was superseded in 2016 by a further revision, the APG IV system.

References

Citations

  1. Angiosperm Phylogeny Group (2009). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III". Botanical Journal of the Linnean Society. 161 (2): 105–121. doi: 10.1111/j.1095-8339.2009.00996.x .
  2. Stearn, William Thomas (2004). Botanical Latin. Timber Press. 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. 1 2 "Angiosperm Phylogeny Website". Mobot.org. Retrieved 12 June 2012.
  5. Lundberg, Johannes (2009). Funk, Vicki A. (ed.). Systematics, Evolution, and Biogeography of Compositae (PDF). International Association for Plant Taxonomy. pp. 157–169. ISBN   978-3-9501754-3-1 . Retrieved 14 April 2020.
  6. Bremer, K.; Gustafsson, M. H. G. (1997). "East Gondwana ancestry of the sunflower alliance of families". Proceedings of the National Academy of Sciences of the United States of America. 94 (17): 9188–9190. Bibcode:1997PNAS...94.9188B. doi:10.1073/pnas.94.17.9188. PMC   23106 . PMID   9256457.
  7. "A Brief Overview of the Compositae, Lettuce and Sunflower". 28 October 2015. Retrieved 14 April 2020.
  8. Wolff, Anita, ed. (2008). Britannica Concise Encyclopedia. Encyclopaedia Britannica, Inc. p. 403. ISBN   978-1-59339-492-9 . Retrieved 14 April 2020.
  9. Wondrich, David (5 August 2008). "The Five Best Bottles of Absinthe". Esquire .

General references