Editing Asparagales (section)

=== Subdivision ===
A [[phylogenetic tree]] for the Asparagales, generally to family level, but including groups which were recently and widely treated as families but which are now reduced to subfamily rank, is shown below.{{sfn|ps=none|Chase et al|2009}}{{sfn|ps=none|Stevens|2016|loc=[http://www.mobot.org/MOBOT/Research/APweb/orders/asparagalesweb.htm#Asparagales Asparagales]}}

{{clade
|  label1=Asparagales
|  1={{clade
|    1=[[Orchidaceae]]
|    2={{clade
|      1={{clade
|        1=[[Boryaceae]]
|        label2=Hypoxidaceae ''s.l.''
|        2={{clade
|          1=[[Blandfordiaceae]]
|          2={{clade
|            1=[[Lanariaceae]]
|            2={{clade
|              1=[[Asteliaceae]]
|              2=[[Hypoxidaceae]]
             }}
           }}
         }}
       }}
|      2={{clade
|        1={{clade
|          1=[[Ixioliriaceae]]
|          2=[[Tecophilaeaceae]]
         }}
|        2={{clade
|          1=[[Doryanthaceae]]
|          2={{clade
|            1=[[Iridaceae]]
|            2={{clade
|              1=[[Xeronemataceae]]
|              2={{clade
|                label1=[[Asphodelaceae]]
|                1={{clade
|                  1=[[Hemerocallidoideae]] (= Hemerocallidaceae)
|                  2={{clade
|                    1=[[Asphodeloideae]] (= Asphodelaceae)
|                    2=[[Xanthorrhoeoideae]] (= Xanthorrhoeaceae ''s.s.'')
                   }}
                 }}
|                label2='core' Asparagales
|                2={{clade
|                  label1=[[Amaryllidaceae]] ''s.l.''
|                  1={{clade
|                    1=[[Agapanthoideae]] (= Agapanthaceae)
|                    2={{clade
|                      1=[[Allioideae]] (= Alliaceae ''s.s.'')
|                      2=[[Amaryllidoideae]] (= Amaryllidaceae ''s.s.'')
                     }}
                   }}
|                  label2=[[Asparagaceae]] ''s.l.''
|                  2={{clade
|                    1={{clade
|                      1=[[Lomandroideae]] (= Laxmanniaceae)
|                      2={{clade
|                        1=[[Asparagoideae]] (= Asparagaceae ''s.s.'')
|                        2=[[Nolinoideae]] (= Ruscaceae)
                       }}
                     }}
|                    2={{clade
|                      1=[[Agavoideae]] (= Agavaceae)
|                      2={{clade
|                        1=[[Aphyllanthoideae]] (= Aphyllanthaceae)
|                        2={{clade
|                          1=[[Brodiaeoideae]] (= Themidaceae)
|                          2=[[Scilloideae]] (= Hyacinthaceae)
                         }}
                       }}
                     }}
                   }}
                 }}
               }}
             }}
           }}
         }}
       }}
     }}
   }}
}}

The tree shown above can be divided into a basal paraphyletic group, the 'lower Asparagales (asparagoids)', from Orchidaceae to Asphodelaceae,{{sfn|ps=none|Rudall|Furness|Chase|Fay|1997}} and a well-supported monophyletic group of 'core Asparagales' (higher asparagoids), comprising the two largest families, Amaryllidaceae ''sensu lato'' and Asparagaceae ''sensu lato''.{{sfn|ps=none|Stevens|2016|loc=[http://www.mobot.org/MOBOT/Research/APweb/orders/asparagalesweb.htm#Asparagales Asparagales]}}

Two differences between these two groups (although with exceptions) are: the mode of [[microsporogenesis]] and the position of the ovary. The 'lower Asparagales' typically have simultaneous microsporogenesis (i.e. cell walls develop only after both [[meiosis|meiotic]] divisions), which appears to be an [[apomorphy]] within the monocots, whereas the 'core Asparagales' have reverted to successive microsporogenesis (i.e. cell walls develop after each division).{{sfn|ps=none|Rudall|2002a}} The 'lower Asparagales' typically have an [[inferior ovary]], whereas the 'core Asparagales' have reverted to a [[superior ovary]]. A 2002 morphological study by Rudall treated possessing an inferior ovary as a [[synapomorphy]] of the Asparagales, stating that reversions to a superior ovary in the 'core Asparagales' could be associated with the presence of nectaries below the ovaries.{{sfn|ps=none|Rudall|2002b}} However, Stevens notes that superior ovaries are distributed among the 'lower Asparagales' in such a way that it is not clear where to place the evolution of different ovary morphologies. The position of the ovary seems a much more flexible character (here and in other [[angiosperm]]s) than previously thought.{{sfn|ps=none|Stevens|2016|loc=[http://www.mobot.org/MOBOT/Research/APweb/orders/asparagalesweb.htm#Asparagales Asparagales]}}

==== Changes to family structure in APG III ====
The [[APG III system]] when it was published in 2009, greatly expanded the families [[Xanthorrhoeaceae]], [[Amaryllidaceae]], and [[Asparagaceae]].{{sfn|ps=none|Chase et al|2009}} Thirteen of the families of the earlier [[APG II system]] were thereby reduced to subfamilies within these three families. The expanded Xanthorrhoeaceae is now called "Asphodelaceae".<ref>{{Cite journal |last=The Angiosperm Phylogeny Group |last2=Chase |first2=M. W. |last3=Christenhusz |first3=M. J. M. |last4=Fay |first4=M. F. |last5=Byng |first5=J. W. |last6=Judd |first6=W. S. |last7=Soltis |first7=D. E. |last8=Mabberley |first8=D. J. |last9=Sennikov |first9=A. N. |last10=Soltis |first10=P. S. |last11=Stevens |first11=P. F. |date=2016-05-01 |title=An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV |url=https://academic.oup.com/botlinnean/article-abstract/181/1/1/2416499?redirectedFrom=fulltext |journal=Botanical Journal of the Linnean Society |volume=181 |issue=1 |pages=1–20 |doi=10.1111/boj.12385 |issn=0024-4074}}</ref> The APG II families (left) and their equivalent APG III subfamilies (right) are as follows:

{| border="0"
|-
| valign="top" |
;Asphodelaceae
* Hemerocallidaceae=[[Hemerocallidoideae]]
* Xanthorrhoeaceae=[[Xanthorrhoeoideae]]
* Asphodelaceae=[[Asphodeloideae]]
| valign="top" |
;Amaryllidaceae
* Agapanthaceae=[[Agapanthoideae]]
* Alliaceae =[[Allioideae]]
* Amaryllidaceae=[[Amaryllidoideae]]
| valign="top" |
;Asparagaceae
* Aphyllanthaceae = [[Aphyllanthoideae]]
* Laxmanniaceae = [[Lomandroideae]]
* Asparagaceae = [[Asparagoideae]]
* Ruscaceae = [[Nolinoideae]]
* Agavaceae = [[Agavoideae]]
* Themidaceae = [[Brodiaeoideae]]
* Hyacinthaceae = [[Scilloideae]]
|}

==== Structure of Asparagales ====

=====Orchid clade=====
[[Orchidaceae]] is possibly the largest family of all [[angiosperm]]s (only [[Asteraceae]] might – or might not – be more speciose) and hence by far the largest in the order. The [[Dahlgren system]] recognized three families of orchids, but DNA sequence analysis later showed that these families are [[polyphyletic]] and so should be combined. Several studies suggest (with high bootstrap support) that Orchidaceae is the sister of the rest of the Asparagales.{{sfn|ps=none|Chase|Fay|Devey|Maurin|2006}}{{sfn|ps=none|Graham|Zgurski|McPherson|Cherniawsky|2006}}{{sfn|ps=none|Pires|Maureira|Givnish|Sytsma|2006}}{{sfn|ps=none|Givnish|Pires|Graham|McPherson|2006}} Other studies have placed the orchids differently in the phylogenetic tree, generally among the [[Boryaceae]]-[[Hypoxidaceae]] clade.{{sfn|ps=none|Janssen|Bremer|2004}}{{sfn|ps=none|Rudall|2002a}}{{sfn|Chase et al.| 1995a}}{{sfn|ps=none|McPherson|Graham|2001}}{{sfn|ps=none|Li|Zhou|2007}} The position of Orchidaceae shown above seems the best current hypothesis,{{sfn|ps=none|Stevens|2016|loc=[http://www.mobot.org/MOBOT/Research/APweb/orders/asparagalesweb.htm#Asparagales Asparagales]}} but cannot be taken as confirmed.

Orchids have simultaneous microsporogenesis and inferior ovaries, two characters that are typical of the 'lower Asparagales'. However, their nectaries are rarely in the septa of the ovaries, and most orchids have dust-like seeds, atypical of the rest of the order. (Some members of [[Vanilloideae]] and [[Cypripedioideae]] have crustose seeds, probably associated with dispersal by birds and mammals that are attracted by fermenting fleshy fruit releasing fragrant compounds, e.g. [[vanilla]].)

In terms of the number of species, Orchidaceae diversification is remarkable, with recent estimations suggesting that despite the old origin of the family dating back to the late cretaceous,<ref>{{Cite journal |last1=Givnish |first1=Thomas J. |last2=Spalink |first2=Daniel |last3=Ames |first3=Mercedes |last4=Lyon |first4=Stephanie P. |last5=Hunter |first5=Steven J. |last6=Zuluaga |first6=Alejandro |last7=Iles |first7=William J. D. |last8=Clements |first8=Mark A. |last9=Arroyo |first9=Mary T. K. |last10=Leebens-Mack |first10=James |last11=Endara |first11=Lorena |last12=Kriebel |first12=Ricardo |last13=Neubig |first13=Kurt M. |last14=Whitten |first14=W. Mark |last15=Williams |first15=Norris H. |date=2015-09-07 |title=Orchid phylogenomics and multiple drivers of their extraordinary diversification |journal=Proceedings of the Royal Society B: Biological Sciences |language=en |volume=282 |issue=1814 |pages=20151553 |doi=10.1098/rspb.2015.1553 |issn=0962-8452 |pmc=4571710 |pmid=26311671}}</ref><ref>{{Cite journal |last1=Serna-Sánchez |first1=Maria Alejandra |last2=Pérez-Escobar |first2=Oscar A. |last3=Bogarín |first3=Diego |last4=Torres-Jimenez |first4=María Fernanda |last5=Alvarez-Yela |first5=Astrid Catalina |last6=Arcila-Galvis |first6=Juliana E. |last7=Hall |first7=Climbie F. |last8=de Barros |first8=Fábio |last9=Pinheiro |first9=Fábio |last10=Dodsworth |first10=Steven |last11=Chase |first11=Mark W. |last12=Antonelli |first12=Alexandre |last13=Arias |first13=Tatiana |date=2021-03-25 |title=Plastid phylogenomics resolves ambiguous relationships within the orchid family and provides a solid timeframe for biogeography and macroevolution |journal=Scientific Reports |language=en |volume=11 |issue=1 |pages=6858 |doi=10.1038/s41598-021-83664-5 |pmid=33767214 |pmc=7994851 |bibcode=2021NatSR..11.6858S |issn=2045-2322}}</ref> modern orchid diversity originated mostly during the last 5 million years.<ref>{{Cite journal |last1=Pérez-Escobar |first1=Oscar A. |last2=Bogarín |first2=Diego |last3=Przelomska |first3=Natalia A. S. |last4=Ackerman |first4=James D. |last5=Balbuena |first5=Juan A. |last6=Bellot |first6=Sidonie |last7=Bühlmann |first7=Roland P. |last8=Cabrera |first8=Betsaida |last9=Cano |first9=Jose Aguilar |last10=Charitonidou |first10=Martha |last11=Chomicki |first11=Guillaume |last12=Clements |first12=Mark A. |last13=Cribb |first13=Phillip |last14=Fernández |first14=Melania |last15=Flanagan |first15=Nicola S. |date=April 2024 |title=The origin and speciation of orchids |url=https://nph.onlinelibrary.wiley.com/doi/10.1111/nph.19580 |journal=New Phytologist |language=en |volume=242 |issue=2 |pages=700–716 |doi=10.1111/nph.19580 |pmid=38382573 |issn=0028-646X|hdl=10550/97112 |hdl-access=free }}</ref> However, although the other Asparagales may be less rich in species, they are more variable morphologically, including tree-like forms.

=====Boryaceae to Hypoxidaceae=====
The four families excluding [[Boryaceae]] form a well-supported clade in studies based on DNA sequence analysis. All four contain relatively few species, and it has been suggested that they be combined into one family under the name Hypoxidaceae ''sensu lato''.{{sfn|ps=none|Soltis|Soltis|Endress|Chase|2005}} The relationship between Boryaceae (which includes only two genera, ''[[Borya]]'' and ''[[Alania (plant)|Alania]]''), and other Asparagales has remained unclear for a long time. The Boryaceae are [[mycorrhiza]]l, but not in the same way as orchids. Morphological studies have suggested a close relationship between Boryaceae and Blandfordiaceae.{{sfn|ps=none|Rudall|2002a}} There is relatively low support for the position of Boryaceae in the tree shown above.{{sfn|ps=none|Chase|Fay|Devey|Maurin|2006}}

=====Ixioliriaceae to Xeronemataceae=====
The relationship shown between [[Ixioliriaceae]] and [[Tecophilaeaceae]] is still unclear. Some studies have supported a clade of these two families,{{sfn|ps=none|Chase|Fay|Devey|Maurin|2006}} others have not.{{sfn|ps=none|Janssen|Bremer|2004}} The position of [[Doryanthaceae]] has also varied, with support for the position shown above,{{sfn|ps=none|Graham|Zgurski|McPherson|Cherniawsky|2006}} but also support for other positions.{{sfn|ps=none|Chase|Fay|Devey|Maurin|2006}}

The clade from [[Iridaceae]] upwards appears to have stronger support. All have some genetic characteristics in common, having lost Arabidopsis-type [[telomere]]s.{{sfn|ps=none|Fay et al|2000}} Iridaceae is distinctive among the Asparagales in the unique structure of the [[inflorescence]] (a rhipidium), the combination of an inferior ovary and three stamens, and the common occurrence of unifacial leaves whereas bifacial leaves are the norm in other Asparagales.

Members of the clade from [[Iridaceae]] upwards have infra-locular septal nectaries, which Rudall interpreted as a driver towards secondarily superior ovaries.{{sfn|ps=none|Rudall|2002b}}

=====Asphodelaceae + 'core Asparagales'=====
The next node in the tree (Xanthorrhoeaceae ''sensu lato'' + the 'core Asparagales') has strong support.{{sfn|ps=none|Chase|De Bruijn|Cox|Reeves|2000}} 'Anomalous' secondary thickening occurs among this clade, e.g. in ''[[Xanthorrhoea]]'' (family Asphodelaceae) and ''[[Dracaena (plant)|Dracaena]]'' (family Asparagaceae ''sensu lato''), with species reaching tree-like proportions.

The 'core Asparagales', comprising Amaryllidaceae ''sensu lato'' and Asparagaceae ''sensu lato'', are a strongly supported clade,{{sfn|ps=none|Graham|Zgurski|McPherson|Cherniawsky|2006}} as are clades for each of the families. Relationships within these broadly defined families appear less clear, particularly within the Asparagaceae ''sensu lato''. Stevens notes that most of its subfamilies are difficult to recognize, and that significantly different divisions have been used in the past, so that the use of a broadly defined family to refer to the entire clade is justified.{{sfn|ps=none|Stevens|2016|loc=[http://www.mobot.org/MOBOT/Research/APweb/orders/asparagalesweb.htm#Asparagales Asparagales]}} Thus the relationships among subfamilies shown above, based on [[APWeb]] {{as of|2010|December|lc=yes}}, is somewhat uncertain.