Amborellaceae
275863
225251463
2008-07-12T18:25:06Z
SmackBot
433328
Date the maintenance tags or general fixes
{{Taxobox
| name = ''Amborella''
| image = Amborella_trichopoda_1.jpg
| image_width = 240px
| image_caption = ''[[Amborella trichopoda]]''
| regnum = [[Plant]]ae
| divisio = [[Angiospermae]]
| classis = ''see text''
| ordo = ''see text''
| familia = '''Amborellaceae'''
| familia_authority = Pichon (1948)
| subdivision_ranks = [[Genus|Genera]]
| subdivision = ''[[Amborella]]''
}}
'''Amborellaceae''', or the Amborella Family, is a family of [[flowering plants]] [[Endemism|endemic]] to [[New Caledonia]]. The family consists of only a single species, ''[[Amborella trichopoda]]''. The [[APG II system|Angiosperm Phylogeny Group]] plant classification system ([[APG II]]) recognizes this family, but does not assign it to an order due to uncertainty about its relationship to the family [[Nymphaeaceae]]. Some cientists working on the family today assign it to its own order, the '''Amborellales'''.{{Fact|date=July 2008}} It is currently accepted by plant systematists working with APG II as the most basal lineage in the [[clade]] '''[[angiosperms]]'''.
By 'most basal' scientists mean that the Amborellaceae diverged the earliest from all other lineages of flowering plants. Comparing the derived characteristics that all other angiosperms share with each other, but not with the Amborella Family, may give scientists clues to what features early flowering plants had and how these characteristics have evolved through time. One early twentieth century idea of "primitive", or less derived, angiosperms that was accepted until relatively recently was modeled on the ''[[Magnolia]]'' blossom with numerous [[Flower|parts]] arranged in spirals on an elongated receptacle rather than the small numbers of parts in distinct whorls of more derived flowers. However, studies of a well-preserved fossil putative aquatic angiosperm, ''[[Archaefructus]]'', have raised questions about what characteristics are more ancestral.
==Description==
The Amborellaceae are sprawling [[shrubs]] or small [[trees]] with two-ranked leaves without [[stipules]]. The leaves have distinctly rippled or wavy margins. The plants are [[dioecious]], and the flowers are small, in terminal cymose [[inflorescence]]s, with a [[perianth]] of undifferentiated sepals and petals arranged in a spiral, rather than in the whorls of more derived angiosperms.
The Amborella Family has parts arranged in a spiral, of an indeterminate number (5-8 [[perianth]] parts), numerous [[stamen]]s without a well-defined stalk or filament, an indeterminate number of free [[carpel]]s (apocarpous). The more derived families of flowering plants (the [[eudicots]]), often have two distinguishable perianth whorls, the calyx and the corolla, each with a well-defined number of parts (4 or 5 is common), stamens on filaments, and compound [[Ovary (plants)|ovaries]] with united carpels (syncarpous).
==Most basal angiosperm==
[[Image:Seed plants evolutionary relationships with Amborella highlighted.jpg|500px|Cladogram showing relationship between ''Amborella'' of the Amborellaceae and other [[seed plants]].|left|500px|Cladogram showing relationship between ''Amborella'' of the Amborellaceae and other [[seed plants]].]]
In a study designed to clarify relationships between the well-sequenced and well-studied model plants such as ''[[Arabidopsis thaliana]]'', and the basal angiosperms such as ''Amborella'', ''[[Nuphar]]'' of the Nymphaeaceae, ''[[Illicium]]'', the [[monocots]], and more derived angiosperms, the eudicots, scientists examined the chloroplast genomes and expressed sequence tags of these organisms, and other seed plants to create this [[cladogram]]. Note that in this image, the angiosperms are all of the plants not labeled "gymnosperms." This hypothesized relationship of the extant seed plants places ''Amborella'' as the [[Cladistics|sister taxon]] to all other angiosperms, and shows the gymnosperms as a monophyletic group sister to the angiosperms, supporting the theory that ''Amborella'' branched off earliest from all other living angiosperms. The dashed line between ''Amborella'' and ''Nuphar'' is meant to indicate some uncertainty about the relationship between the Amborellaceae and the Nymphaeaceae, and whether or not they form a clade that is sister to the angiosperms, rather than ''Amborella'' alone being a monophyletic group sister to the angiosperms.
==Other plant classification systems==
The [[Cronquist system]], of 1981, assigned the family
: to the order [[Laurales]]
:: in subclass [[Magnoliidae]],
::: in class [[Magnoliopsida]] [=[[dicotyledons]]]
:::: of division [[Magnoliophyta]] [=angiosperms].
----
The [[Thorne system (1992)]] placed it
: in the order [[Magnoliales]], which was assigned
:: to superorder [[Magnolianae]],
::: in subclass Magnoliideae [=dicotyledons],
:::: in class Magnoliopsida [=angiosperms].
----
The [[Dahlgren system]] placed it
: in the order Laurales, which was assigned
:: to superorder Magnolianae
::: in subclass Magnoliideae [=dicotyledons],
:::: in class Magnoliopsida [=angiosperms].
== External links ==
:* [http://delta-intkey.com/angio/www/amborell.htm Amborellaceae] in L. Watson and M.J. Dallwitz (1992 onwards). ''[http://delta-intkey.com/angio/ The families of flowering plants]: descriptions, illustrations, identification, information retrieval.'' Version: 3rd May 2006. http://delta-intkey.com
:* [http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Tree&id=22097&lvl=3&lin=f&keep=1&srchmode=1&unlock NCBI Taxonomy Browser]
== References ==
* Simpson, M.G. ''Plant Systematics''. Elsevier Academic Press. 2006.
* Albert, V.A., et al., Floral gene resources from basal angiosperms for comparative genomics research, 2005. BMC Plant Biology, http://bmc.ub.uni-potsdam.de/1471-2229-5-5/1471-2229-5-5.pdf.
[[Category:Angiosperms]]
[[Category:plant families]]
[[Category:Monotypic plant genera]]
[[ca:Amborellaceae]]
[[da:Amborellaceae]]
[[es:Amborellaceae]]
[[fr:Amborellaceae]]
[[nl:Amborellaceae]]
[[ja:アムボレラ科]]
[[pl:Amborellaceae]]
[[sr:Amborellaceae]]
[[zh:無油樟科]]