Urticales is a botanical name for what used to be an order of flowering plants. Before molecular phylogenetics became an important part of plant taxonomy, Urticales was recognized in many, perhaps even most, systems of plant classification, with some variations in circumscription. Among these is the Cronquist system (1981), which placed the order in the subclass Hamamelidae [sic], as comprising :
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 statistical support in phylogenetic analyses of DNA sequences. This clade has been informally called the urticalean rosids.
Urticaleean rosids refers to the relationships amongst several families of angiosperms, and now includes more than 2,500 species.
The families are
The relationships within the "urticalean lineage" are now considered in the current definition of Rosales, which includes Barbeyaceae, Dirachmaceae, Elaeagnaceae, and Rhamnaceae. (APG, 1998) Moraceae and Urticaceae account for approximately 90% of the diversity within the order.  T
Analysis of DNA samples in rbcL, trnL-F, and ndhF plastid regions, concludes
"Urticalean rosids are derived out of a lineage including Barbeyaceae, Dirachmaceae, Elaegnaceae, and Rhamnaceae, with Rosaceae less closely related; thus, they are imbedded within the Rosales. Ulmaceae are the sister to all remaining families."'
Morphological and molecular characters which define "urticalean rosids,"
- A dense gray tomentum composed of curly unicellular trichomes on abaxial leaf surfaces (Tobe and Takahashi, 1990) 
Urticalean families represent 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, Ulmaceae, and Celitdaceae do not produce this material despite the presence of laticifers. The three, including Rhamnaceae, also share the plesiomorphic feature of polyembryony. This characteristic is absent in Urticaceae, Cecropiaceae, and Moraceae.(Dahlgren, 1991⇓; Qiu et al., 1998⇓).
Cannabaceae was once associated with Moraceae, or placed in an ambiguous position amongst other families within the Urticales, as it is a small family with distinctive characteristics. Current genetic research (Sytsma et al. 2002)  has proven that Cannabaceae diverged from the Urticales group of Rosales before the divergence of the Moraceae and the Urticaceae, and is an evolutionarily older plant. Cannabaceae is also more often an herb or herbaceous vine rather than woody in structure as Ulmaceae and Celtidaceae.
Further DNA analysis supports Cannabaceae's origin from Celtidaceae. Cannabaceae and Celtidaceae alone share a derived base chromosome within the Urticalean rosids. (Mehra and Gill, 1974)  They also share micropapillate or smooth surface features in nonglandular trichomes, found less frequently within secluded genera within the Urticaceae. (Tobe and Takaso, 1996)  Thus Cannabaceae and Celtidaceae should be merged as one family, though this new classification is confusing, as the name Cannabaceae (Martynov, 1820) predates Celtidaceae (Link, 1831.) The result is a preference for the term "Cannabaceae" when defining this family and its new distinction from Ulmaceae.
The species within Cannabaceae have an ovary with two (occasionally reduced) styles, (similar to Ulmaceae, Moraceae, and Celtidaceae.) However, they also share a pendulous, apical, and anatropous ovule, rather than a pseudo-monomerous ovary with one style, in addition to a basal erect orthotropous ovule. (A trait also shared with Urticaceae and Cecropiaceae.)(Sytsma, Morawetz, Pires, Nepokroeff, Conti, Zjra, Hall, Chase, 2001.) 
Additional research from Sytsma et al. suggests that Aphananthe, Lozanella, Parasponia, and Pteroceltis receive their own subfamilies within Cannabaceae, as they are all derived from Celtidaceae.
- 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.
- 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. PDF fulltext
- 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.
- APG (Angiosperm Phylogeny Group). 1998. An ordinal classification for the families of flowering plants. Annals of the Missouri Botanical Garden 85: 531-553. .
- Sytsma, Kenneth J., Jeffery Morawetz, J. Chris Pires, Molly Nepokroeff, Elena Conti, Michelle Zjra, Jocelyn C. Hall, and Mark W. Chase. "American Journal of Botany." Urticalean Rosids: Circumscription, Rosid Ancestry, and Phylogenetics Based on RbcL, TrnL-F, and NdhF Sequences. American Journal of Botany, 15 Nov. 2001. Web. 12 Dec. 2013..
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- Judd W. S. C. S. Campbell E. A. Kellogg P. F. Stevens 1999. Plant systematics: a phylogenetic approach. Sinauer Associates, Sunderland, Massachusetts, USA.
- Stevens P. F. 2001. Angiosperm phylogeny website, v. 2, August 2001. http://www.mobot.org/MOBOT/research/APweb/.
- Dahlgren G. 1989. The last Dahlgrenogram, system of classification of the dicotyledons. In K. Tan [ed.], Plant taxonomy, phytogeography and related subjects, 249–260. Edinburgh University Press, Edinburgh, Scotland.
- Mehra P. N. R. S. Gill 1974. Cytological studies in Ulmaceae, Moraceae and Urticaceae. Journal of the Arnold Arboretum 55: 663-677.
- Tobe H. T. Takaso 1996. Trichome micromorphology in Celtidaceae and Ulmaceae (Urticales). Acta Phytotaxonomica et Geobotanica 47: 153-168.