Order of flowering plants
Urticales is anorder offlowering plants. Beforemolecular phylogenetics became an important part ofplant taxonomy, Urticales was recognized in many, perhaps even most,systems ofplant classification, with some variations incircumscription. Among these is theCronquist system (1981), which placed the order in thesubclassHamamelidae [sic], as comprising:
In theAPG III system (2009), the plants belonging to this order, along with four other families, constitute the orderRosales. Cecropiaceae is no longer recognized as separate from Urticaceae. The families Ulmaceae, Cannabaceae, Moraceae, and Urticaceae form aclade that has strongstatistical support inphylogenetic analyses ofDNA sequences.[1] This clade has been informally called the urticalean rosids.[2]
Urticalean 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 to be within the Rosales.[4] The Moraceae and Urticaceae account for approximately 90% of the diversity within the clade.[5]
Analysis of DNA samples inrbcL,trnL-F, andndhF plastid regions suggests that Urticalean rosids are derived out of a lineage includingBarbeyaceae,Dirachmaceae,Elaeagnaceae, andRhamnaceae, with Rosaceae less closely related.[5] The morphological and molecular characters which define "urticalean rosids" are:
- A dense gray tomentum comprising curly unicellular trichomes on abaxial leaf surfaces[6]
- A reduced stamen count to one whorl or less[7][8]
- Presence of inconspicuous flowers with up to five stamens[7][8]
- Presence of two carpels[7][8]
- A unilocular ovary with single apical ovule[7][8]
- Urticoid teeth upon leaves[7][8]
- Developed prophyllar buds between paired inflorescences[7][8]
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.
- ^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 Evolution60(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 onrbcL,trnL-F, andndhF sequences.American Journal of Botany89(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.
- ^abSytsma, 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
- ^Tobe H. and T. Takaso 1996. Trichome micromorphology in Celtidaceae and Ulmaceae (Urticales). Acta Phytotaxonomica et Geobotanica 47: 153–168.
- ^abcdefJudd W. S. C. S. Campbell E. A. Kellogg P. F. Stevens 1999. Plant systematics: a phylogenetic approach. Sinauer Associates, Sunderland, Massachusetts, USA.
- ^abcdefStevens P. F. 2001. Angiosperm phylogeny website, v. 2, August 2001.http://www.mobot.org/MOBOT/research/APweb/.
