Huerteales

Huerteales is the botanical name for an order of flowering plants.Peter F. Stevens (2001 onwards). "Huerteales". In: Angiosperm Phylogeny Website. In: Missouri Botanical Garden Website. (see ''External links'' below) It is one of the 17 orders that make up the large eudicot group known as the rosids in the APG III system of plant classification. Within the rosids, it is one of the orders in Malvidae, a group formerly known as eurosids II and now known informally as the malvids. This is true whether Malvidae is circumscribed broadly to include eight orders as in APG III, or more narrowly to include only four orders. Huerteales consists of four small families, Petenaeaceae, Gerrardinaceae, Tapisciaceae, and Dipentodontaceae.Andreas Worberg, Mac H. Alford, Dietmar Quandt, and Thomas Borsch. 2009. "Huerteales sister to Brassicales plus Malvales, and newly circumscribed to include ''Dipentodon, Gerrardina, Huertea, Perrottetia, and ''Tapiscia''. ''Taxon'' 58(2):468-478.

Petenaeaceae consists of a single genus and species ''Petenaea cordata'' from Southern Mexico, Guatemala and Belize.Christenhusz, M. J. M., Fay, M. F., Clarkson, J. J., Gasson, P., Morales Can, J., Jiménez Barrios, J. B. & Chase, M. W. (2010). Petenaeaceae, a new angiosperm family in Huerteales with a distant relationship to ''Gerrardina'' (Gerrardinaceae). Botanical Journal of the Linnean Society 164: 16–25.

Gerrardinaceae consists of a single genus, '' Gerrardina''.Mac H. Alford. 2006. "Gerrardinaceae: a new family of African flowering plants unresolved among Brassicales, Huerteales, Malvales, and Sapindales." ''Taxon'' 55(4):959-964. Tapisciaceae has two genera, '' Tapiscia'' and ''Huertea''.Klaus Kubitzki. 2003. "Tapisciaceae" pages 369-370. In: Klaus Kubitski and Clemens Bayer (editors). ''The Families and Genera of Vascular Plants'' volume V. Springer-Verlag: Berlin;Heidelberg, Germany.Dezhu Li, Jie Cai, and Wen Jun. 2008. "Tapisciaceae" page 496. In: Zhengyi Wu, Peter H. Raven, and Deyuan Hong (editors). ''Flora of China'' volume 11. Science Press: Beijing, China; Missouri Botanical Garden Press: St. Louis, Missouri, USA.

Until 2006, Dipentodontaceae was treated as consisting of a single genus, ''Dipentodon''.Vernon H. Heywood, Richard K. Brummitt, Ole Seberg, and Alastair Culham. ''Flowering Plant Families of the World''. Firefly Books: Ontario, Canada. (2007). Since that time, some authors have included ''Perrottetia'' in Dipentodontaceae, even though no formal revision of the family has been published as of 2008.Jinshuang Ma and Bruce Bartholomew. 2008. "Dipentodontaceae" pages 494-495. In: Zhengyi Wu, Peter H. Raven, and Deyuan Hong (editors). ''Flora of China'' volume 11. Science Press: Beijing, China; Missouri Botanical Garden Press: St. Louis, Missouri, USA. Thus the order Huerteales consists of six genera. The largest genus, ''Perrottetia'', contains about 15 of the approximate total of 25 species in the order.Mark P. Simmons. 2004. "Celastraceae" page 50. In: Klaus Kubitzki (editor). ''The Families and Genera of Vascular Plants'' volume VI. Springer-Verlag: Berlin;Heidelberg, Germany.

The Huerteales are shrubs or small trees found in most tropical or warm temperate regions. The flowers of ''Perrottetia'' have been studied in detail,Merran L. Matthews and Peter K. Endress (2005). "Comparative floral structure and systematics in Celastrales". ''Botanical Journal of the Linnean Society'' 149(2):129-194 but otherwise, all five of the genera are poorly known. The order is based on molecular phylogenetic analysis of DNA sequences.

Description

All of the Huerteales are woody plants. The leaves are alternate with toothed margins. The inflorescence is cymose, but sometimes nearly racemose or umbelliform. The bases of the calyx, corolla and stamens are fused to form a hypanthium which is in some cases very short. The ovary is unilocular, at least at the top, with one or two ovules per carpel. The number of carpels is variable.

Other characters are generally found in Huerteales, but with the exceptions noted below. ''Gerrardina'' differs from the rest of Huerteales in that the stamens are opposite the petals, instead of being opposite the sepals. ''Dipentodon'' and ''Perrottetia'' are distinctive in that the calyx and corolla are not well differentiated, but resemble each other. ''Tapiscia'' and ''Huertea'' have a calyx tube and compound, rather than simple leaves. ''Tapiscia'' has a uniloculate ovary with a single ovule. ''Huertea'' has one locule containing two ovules, or two locules, each containing one ovule. ''Gerrardina'', ''Dipentodon'', and ''Perrottetia'' have two ovules in each locule. ''Tapiscia'' lacks the nectary disk that is characteristic of the order. ''Huertea'' lacks stipules.

History

Until the first decade of the twenty-first century, the five genera of Huerteales had usually been placed into three unrelated families. ''Tapiscia'' and ''Huertea'' had long been known to be related. Most authors had placed them in Staphyleaceae and had placed that family in the order Sapindales. Armen Takhtajan established the family Tapisciaceae in 1987 and placed it in Sapindales, but this treatment was not followed by many others and it did not stand up to phylogenetic analysis. Since that time, Staphyleaceae has been recircumscribed. It no longer includes ''Tapiscia'' and ''Huertea'' Sarah L. Simmons. 2007. "Staphyleaceae" pages 440-445. In: Klaus Kubitzki (editor). ''The Families and Genera of Vascular Plants'' volume IX. Springer-Verlag: Berlin;Heidelberg, Germany. and it is in the order Crossosomatales.Sang-Hun Oh and Daniel Potter. 2006. "Description and Phylogenetic Position of a New Angiosperm Family, Guamatelaceae, Inferred from Chloroplast ''rbcL, atpB,'' and ''matK'' Sequences." ''Systematic Botany'' 31(4):730-738.

For most of the twentieth century, ''Gerrardina'' and ''Dipentodon'' had usually been placed in Flacourtiaceae, a family that is now recognized by only a few taxonomists, and then only as a segregate of Salicaceae.Mark W. Chase, Sue Zmarzty, M. Dolores Lledó, Kenneth J. Wurdack, Susan M. Swensen, and Michael F. Fay. 2002. "When in doubt, put it in Flacourtiaceae: a molecular phylogenetic analysis based on plastid ''rbcL'' DNA sequences." ''Kew Bulletin'' 57(1):141-181.Sue Zmarzty et alii. (in press). "Salicaceae" In: ''The Families and Genera of Vascular Plants''. Springer-Verlag: Berlin;Heidelberg, Germany. ''Perrottetia'', meanwhile, had usually been placed, with considerable doubt, in Celastraceae.Li-Bing Zhang and Mark P. Simmons (2006). "Phylogeny and Delimitation of the Celastrales Inferred from Nuclear and Plastid Genes". ''Systematic Botany'' 31(1):122-137.

Ever since ''Dipentodon'' was named in 1911, there had been occasional suggestions that it might be related to ''Tapiscia'' and ''Huertea''. In 2001, Alexander Doweld established the order Huerteales,James L. Reveal. 2008 onward. "A Checklist of Family and Suprafamilial Names for Extant Vascular Plants." At: Home page of James L. Reveal and C. Rose Broome. (see ''External links'' below). defining it to consist of ''Tapiscia'', ''Huertea'', and ''Dipentodon''.Alexander B. Doweld. 2001. ''Tentamen Systematis Plantarum Vascularium (Tracheophyta).'': xxxv. 23 Dec 2001. This grouping was later supported by molecular phylogenetic studies. In 2006, a study of DNA sequences showed that ''Perrottetia'' was misplaced in Celastrales and that it is sister to ''Dipentodon'' in Huerteales. Also in 2006, it was found that ''Gerrardina'' is a malvid, but its placement within this group remained uncertain.

In 2009, Andreas Worberg and co-authors produced the first phylogenetic study that included all of the genera of Huerteales. From one of their data matrices, they derived a well supported phylogeny for the order, as well as strongly supported relationships among the four orders of malvids.

Phylogeny

The phylogeny shown below is the one found by Worberg and co-authors. Monospecific genera are represented by species names.

References

External links

Huerteales
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Missouri Botanical Garden Website


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James L. Reveal

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Angiosperm orders