Editing Urticales

{{Short description|Order of flowering plants}}
'''Urticales''' is an [[Order (biology)|order]] of [[flowering plant]]s. Before [[molecular phylogenetics]] became an important part of [[plant taxonomy]], Urticales was recognized in many, perhaps even most, [[list of systems of plant taxonomy|systems]] of [[History of plant systematics|plant classification]], with some variations in [[Circumscription (taxonomy)|circumscription]]. Among these is the [[Cronquist system]] (1981), which placed the order in the [[subclass (biology)|subclass]] [[Hamamelidae]] {{sic}}, as comprising:
* [[Barbeyaceae]]
* [[Cannabaceae]]
* [[Cecropiaceae]]
* [[Moraceae]]
* [[Ulmaceae]]
* [[Urticaceae]]

In the [[APG III system]] (2009), the plants belonging to this order, along with four other families, constitute the order [[Rosales]]. Cecropiaceae is no longer recognized as separate from Urticaceae. The families Ulmaceae, Cannabaceae, Moraceae, and Urticaceae form a [[clade]] that has strong [[Resampling (statistics)|statistical support]] in [[phylogenetic]] analyses of [[DNA sequence]]s.<ref name="zhang2011">Shu-dong Zhang, Douglas E. Soltis, Yang Yang, De-zhu Li, and Ting-shuang Yi. "Multi-gene analysis provides a well-supported phylogeny of Rosales". ''Molecular Phylogenetics and Evolution'' '''60'''(1):21-28.</ref> This clade has been informally called the urticalean rosids.<ref name="Sytsma2002">Kenneth J. Sytsma, Jeffery Morawetz, J. Chris Pires, Molly Nepokroeff, Elena Conti, Michelle Zjhra, Jocelyn C. Hall, and Mark W. Chase. (2002). Urticalean rosids: Circumscription, rosid ancestry, and phylogenetics based on ''rbcL'', ''trnL-F'', and ''ndhF'' sequences. ''[[American Journal of Botany]]'' '''89'''(9): 1531-1546. [https://bsapubs.onlinelibrary.wiley.com/doi/pdfdirect/10.3732/ajb.89.9.1531 PDF fulltext]</ref>

'''Urticalean rosids''' refers to the relationships amongst several families of angiosperms, and now includes more than 2,500 species.

The families are:
* [[Cannabaceae]]
* [[Moraceae]]
* [[Ulmaceae]]
* [[Urticaceae]]<ref name="Qiu1998">Qiu Y.-L. M. W. Chase S. B. Hoot E. Conti P. R. Crane K. J. Sytsma C. R. Parks 1998. Phylogenetics of the Hamamelidae and their allies: parsimony analyses of nucleotide sequences of the plastid gene rbcL. International Journal of Plant Sciences 159: 891-905.</ref>

The relationships within the "urticalean lineage" are now considered to be within the Rosales.<ref name="APG1998">APG (Angiosperm Phylogeny Group). 1998. An ordinal classification for the families of flowering plants. Annals of the Missouri Botanical Garden 85: 531-553.</ref> The Moraceae and Urticaceae account for approximately 90% of the diversity within the clade.<ref name="Sytsma2001">Sytsma, Kenneth J., Jeffery Morawetz, J. Chris Pires, Molly Nepokroeff, Elena Conti, Michelle Zjra, Jocelyn C. Hall, and Mark W. Chase. 2001. Urticalean Rosids: Circumscription, Rosid Ancestry, and Phylogenetics Based on RbcL, TrnL-F, and NdhF Sequences. American Journal of Botany</ref>

Analysis of DNA samples in ''rbcL'', ''trnL-F'', and ''ndhF'' plastid regions suggests that Urticalean rosids are derived out of a lineage including [[Barbeyaceae]], [[Dirachmaceae]], [[Elaeagnaceae]], and [[Rhamnaceae]], with Rosaceae less closely related.<ref name="Sytsma2001" /> The morphological and molecular characters which define "urticalean rosids" are:
* A dense gray tomentum comprising curly unicellular trichomes on abaxial leaf surfaces <ref name="TOBE1996">Tobe H. and T. Takaso 1996. Trichome micromorphology in Celtidaceae and Ulmaceae (Urticales). Acta Phytotaxonomica et Geobotanica 47: 153–168.</ref>
* A reduced stamen count to one whorl or less<ref name="Judd1999">Judd W. S. C. S. Campbell E. A. Kellogg P. F. Stevens 1999. Plant systematics: a phylogenetic approach. Sinauer Associates, Sunderland, Massachusetts, USA.</ref><ref name="Stevens2001">Stevens P. F. 2001. Angiosperm phylogeny website, v. 2, August 2001. http://www.mobot.org/MOBOT/research/APweb/.</ref>
* Presence of inconspicuous flowers with up to five stamens<ref name="Judd1999" /><ref name="Stevens2001" />
* Presence of two carpels<ref name="Judd1999" /><ref name="Stevens2001" />
* A unilocular ovary with single apical ovule<ref name="Judd1999" /><ref name="Stevens2001" />
* Urticoid teeth upon leaves <ref name="Judd1999" /><ref name="Stevens2001" />
* Developed prophyllar buds between paired inflorescences<ref name="Judd1999" /><ref name="Stevens2001" />

Urticalean families span a wide range of morphological features—deciduous or evergreen trees, vines, shrubs, annuals and some succulents. Leaves also vary though they tend to share brochidodromous or palmately pinnate venation, often associated with lobing or compounding in the leaf blade. Among Moraceae, Urticacae and Cecropiaceae, mucilage cells and latex production is common. However, Cannabaceae and Ulmaceae do not produce this material despite the presence of laticifers.

== References ==
{{Reflist}}

{{Authority control}}

[[Category:Historically recognized angiosperm orders]]