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 Sunflower, Helianthus annuus
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The Asterales are an order of dicotyledonous flowering plants which include the composite family Asteraceae (sunflowers, daisies, thistles etc. The family Stylidiaceae is a taxon of dicotyledonous Flowering plants It consists of five genera with over 240 species most of which are endemic to The family Stylidiaceae is a taxon of dicotyledonous Flowering plants It consists of five genera with over 240 species most of which are endemic to This article is about the taxonomic rank for the sequence of species in a taxonomic list see Taxonomic order In scientific classification used Dicotyledons, or "dicots", is a name for a group of Flowering plants whose Seed typically has two embryonic leaves or Cotyledons There The flowering plants or angiosperms ( Angiospermae or Magnoliophyta) are the most widespread group The family Asteraceae or Compositae (known as the aster, daisy, or sunflower family) is the largest family of Flowering The sunflower ( Helianthus annuus) is an Annual plant in the family Asteraceae and native to the Americas, with a large flowering Bellis is a genus of 15 species of Flowering plants in the family Asteraceae, native to Europe and the Mediterranean region and northern This article is about the plant for other uses see Thistle (disambiguation. ) and its related families.
The order is cosmopolitic, and includes mostly herbaceous species, although a small number of trees (Lobelia) and shrubs is also present.
The Asterales can be characterized on the morphological and molecular level. Synapomorphies include the oligosaccharide inulin as the nutrients storage, and the stamens are usually aggregated densely around the style or even are fused into a tube around it. An oligosaccharide is a Saccharide polymer containing a small number (typically three to ten of component sugars also known as Simple sugars. Inulins are a group of naturally occurring Polysaccharides (several simple sugars linked together produced by many types of plants The last property is probably associated with the plunger (or secondary) pollination, which is common among the families of the order. Pollination in angiosperms and Gymnosperms is the process that transfers pollen grains, which contain the male Gametes (sperm to where the female
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Families
The Asterales include about eleven families, the largest of which are Asteraceae, with about 25,000 species, and Campanulaceae, with about 2,000 species. The family Asteraceae or Compositae (known as the aster, daisy, or sunflower family) is the largest family of Flowering The family Campanulaceae (also bellflower family) of the order Asterales, contains about 70 genera and 2000 Species The remaining families count together for less than 500 species. The two large families are cosmopolitic with center of mass in the northern hemisphere, and the smaller ones are usually confined to Australia and the adjacent areas, or sometimes South America.
Under the Cronquist system, Asteraceae was the only family in the group, but newer systems (e. A system of plant taxonomy, the Cronquist system is a scheme for the classification of flowering plants (or Angiosperms) The family Asteraceae or Compositae (known as the aster, daisy, or sunflower family) is the largest family of Flowering g. APG II) have expanded it. The Angiosperm Phylogeny Group, or APG, refers to two international groups of systematic botanists who came together to try to establish a consensus view of the
Evolution and biogeography
The Asterales order probably originated in the Cretaceous on the supercontinent Gondwana, in the area which is now Australia and Asia. The Cretaceous (kriːˈteɪʃəs, usually abbreviated 'K' for its German translation "Kreide" is a geologic period and system, reaching from the end of Gondwana (ɡɒnˈdwɑːnə originally Gondwanaland) was a southern Supercontinent that existed about 500 to 200 Ma ago Although most extant species are herbaceous, the examination of the basal families in the order suggests that the common ancestor of the order was an arborescent plant.
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 pollen is known for Asteraceae and Goodeniaceae, and seeds from Oligocene and Miocene are known for Menyanthaceae and Campanulaceae respectively. The Oligocene is a geologic epoch of the Paleogene period and extends from about 33 The Miocene is a geological epoch of the Neogene period and extends from about 23
(Bremer and Gustafsson, 1997)
Economical importance
The Asteraceae include some species grown for food, including sunflower (Helianthus annuus), lettuce (Lactuca sativa) and chicory (Cichorium). The sunflower ( Helianthus annuus) is an Annual plant in the family Asteraceae and native to the Americas, with a large flowering Lettuce ( Lactuca sativa) is a Temperate annual or Biennial plant of the daisy family Asteraceae. Common Chicory ( Cichorium intybus) is a bushy perennial Herb with blue lavender or occasionally white Flowers It grows Many spices and medicinal herbs are also present.
Of horticultural importance are the Asteraceae (e. g. chrysanthemum) and Campanulaceae. Chrysanthemums, often called 'mums' are a genus ( Chrysanthemum) of about 30 species of perennial Flowering plants in the family Asteraceae
References
- K. Bremer, M. H. G. Gustafsson (1997). East Gondwana ancestry of the sunflower alliance of families. Proceedings of the National Academy of Sciences U. S. A. 94, 9188-9190. (Available online: Abstract | Full text (HTML) | Full text (PDF))
- W. S. Judd, C. S. Campbell, E. A. Kellogg, P. F. Stevens, M. J. Donoghue (2002). Plant Systematics: A Phylogenetic Approach, 2nd edition. pp. 476-486 (Asterales). Sinauer Associates, Sunderland, Massachusetts. ISBN 0-87893-403-0.
- J. Lindley (1833). John Lindley ( February 8, 1799 - November 1, 1865) was an English Botanist. Nixus Plantarum, 20. Londini.
- Smissen, R. D. (December 2002). Asterales (Sunflower). In: Nature Encyclopedia of Life Sciences. Nature Publishing Group, London. (Available online: DOI | ELS site)
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