Boraginales

Boraginales
Echium vulgare
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Asterids
Order: Boraginales

Boraginales is a valid taxonomic name at the rank of order for a group of flowering plants. When recognized, it includes Boraginaceae and closely related asterid families.

Boraginales is recognized in neither of two major classification systems, the Cronquist system and the APG III system, but has been recognized in some recent scientific papers.[1] The circumscription of Boraginales is essentially identical to the circumscription of Boraginaceae sensu APG. The APG III system takes a broad view of Boraginaceae, including within it the traditionally recognized families Hydrophyllaceae and Lennoaceae based on recent molecular phylogenies that show that Boraginaceae, as traditionally defined, is paraphyletic over these two families. APG III includes Boraginaceae in the Euasterid I (lamiid) clade but this family is otherwise unplaced; its precise relationship to other families in the Euasterid I group remains unclear. In a phylogenetic study of DNA sequences of selected genes, Boraginales was resolved as sister to Lamiales sensu APG, but that result had only 65% maximum likelihood bootstrap support.[2]

In the Cronquist system, Boraginaceae (including Cordiaceae, Ehretiaceae, and Heliotropiaceae) and Lennoaceae were placed in Lamiales, and Hydrophyllaceae in Solanales.

In some recent publications, Boraginaceae sensu APG has been recognized at the rank of order as Boraginales. As such, it has been split into several families: Boraginaceae s.s., Cordiaceae, Ehretiaceae, Heliotropiaceae, and Hydrophyllaceae. Some authors have defined a Boraginaceae sensu strictissimo by recognizing Codonaceae and Wellstediaceae as monogeneric families separate from Boraginaceae sensu stricto.[3] Boraginaceae is hard to characterize morphologically if it includes the genera Codon and Wellstedia.[4] Codon was long regarded as an unusual member of Hydrophyllaceae, but in 1998, a molecular phylogenetic study showed that it is closer to Boraginaceae.[5]

The achlorophyllous holoparasites Lennoa and Pholisma were once regarded as a family, Lennoaceae, but it is now known that they form a clade that is nested within Ehretiaceae.[6] Some studies have indicated that Hydrophyllaceae is paraphyletic if the tribe Nameae is included within it, but further studies will be needed to resolve this issue.[2]

The inclusion of the genus Hoplestigma in Boraginales was occasionally doubted until it was strongly confirmed in a cladistic study in 2014.[1] Hoplestigma is the closest relative of Cordiaceae and it has been recommended that the latter be expanded to include it.

Hydrolea was thought to belong in Hydrophyllaceae for more than a century after it was placed there by Asa Gray, but it is now known to belong in the order Solanales as sister to Sphenoclea.[2]

Pteleocarpa was long regarded as an anomaly, and was usually placed in Boraginales, but with considerable doubt. The molecular evidence strongly supports it as sister to Gelsemiaceae,[2] and that family has been expanded to include it.[7]

References

  1. 1 2 Maximilian Weigend, Federico Luebert, Marc Gottschling, Thomas L.P. Couvreur, Hartmut H. Hilger and James S. Miller. 2014. "From capsules to nutlets — phylogenetic relationships in the Boraginales". Cladistics 30(5):508-518. doi:10.1111/cla.12061.
  2. 1 2 3 4 Nancy F. Refulio-Rodriguez and Richard G. Olmstead. 2014. "Phylogeny of Lamiidae". American Journal of Botany 101(2):287-299. doi:10.3732/ajb.1300394
  3. ↑ Peter F. Stevens (2001 onwards). "Boraginaceae" At: Angiosperm Phylogeny Website. At: Missouri Botanical Garden Website. (see External links below)
  4. ↑ James I. Cohen. 2014. "A phylogenetic analysis of morphological and molecular characters of Boraginaceae: evolutionary relationships, taxonomy, and patterns of character evolution". Cladistics 30(2):139-169. doi:10.1111/cla.12036
  5. ↑ Diane M. Ferguson. 1998. "Phylogenetic Analysis and Relationships in Hydrophyllaceae Based on ndhF Sequence Data". Systematic Botany 23(3):253-268.
  6. ↑ Marc Gottschling, Federico Luebert, Hartmut H. Hilger, and James S. Miller. 2014. "Molecular delimitations in the Ehretiaceae (Boraginales)". Molecular Phylogenetics and Evolution 72:1-6. doi:10.1016/j.ympev.2013.12.005
  7. ↑ Lena Struwe, Valerie L. Soza, Sugumaran Manickam, and Richard G. Olmstead. 2014. "Gelsemiaceae (Gentianales) expanded to include the enigmatic Asian genus Pteleocarpa". Botanical Journal of the Linnean Society 175(4):482–496. doi:10.1111/boj.12182.

Sources

External links

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