Cornales

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Cornales
Temporal range: Coniacian–Recent
Davidia1.jpg
Dove tree in flower
a species in Nyssaceae
Scientific classification e
Kingdom: Plantae
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Cornales
Link[1]
Families

The Cornales are an order of flowering plants, basal among the asterids, containing about 600 species. Plants within the Cornales usually have four-parted flowers, drupaceous fruits, and inferior gynoecia topped with disc-shaped nectaries.

Taxonomy[edit]

In the classification system of Dahlgren the Cornales were in the superorder Corniflorae (also called Cornanae). Under the APG IV system, the Cornales order includes these families:[2]

The oldest fossils assigned with confidence to the order are Hironoia fusiformis, described from Coniacian age Japanese coalified fruits, and Suciacarpa starrii described from American permineralized fruits of Campanian age.[3]

Phylogeny[edit]

The Cornales order is sister to the remainder of the large and diverse asterid clade. The Cornales are highly geographically disjunct and morphologically diverse, which has led to considerable confusion regarding the proper circumscription of the groups within the order and the relationships between them.[4] Under the Cronquist system, the order comprised the families Cornaceae, Nyssaceae, Garryaceae, and Alangiaceae, and was placed among the Rosidae, but this interpretation is no longer followed. Many families and genera previously associated with the Cornales have been removed, including Garryaceae, Griselinia, Corokia, and Kaliphora, among others.[4]

Molecular data suggest four clades are within the Cornales: Cornus-Alangium, nyssoids-mastixioids, Hydrangeaceae-Loasaceae, and Grubbia-Curtisia, with the Hydrostachyaceae in an uncertain position, possibly basal.[5] However, the relationship between these clades is unclear, and as a result of many historical taxonomic interpretations and differing opinions regarding the significance of morphological variations, rankings of taxa within the order are inconsistent.[4][5][6] These difficulties in interpreting the systematics of Cornales may represent an early and rapid diversification of the groups within the order.[5]

References[edit]

  1. ^ Angiosperm Phylogeny Group (2009). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III" (PDF). Botanical Journal of the Linnean Society. 161 (2): 105–121. doi:10.1111/j.1095-8339.2009.00996.x. Retrieved 2013-07-06. 
  2. ^ Angiosperm Phylogeny Group (2016). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV" (PDF). Botanical Journal of the Linnean Society. 181 (1): 1–20. ISSN 0024-4074. doi:10.1111/boj.12385. 
  3. ^ Atkinson, B. (2016). "Early diverging asterids of the Late Cretaceous: Suciacarpa starrii gen. et sp. nov. and the initial radiation of Cornales". Botany. 94: 759–771. doi:10.1139/cjb-2016-0035. 
  4. ^ a b c Xiang, Q. Y., Soltis, D. E., Morgan, D. R., and Soltis, P. S. (1993). Phylogenetic relationships of Cornus L sensu lato and putative relatives inferred from rbcL sequence data. Annals of the Missouri Botanical Garden 80, 723-734.
  5. ^ a b c Fan, C. Z., and Xiang, Q. Y. (2003). Phylogenetic analyses of Cornales based on 26S rRNA and combined 26S rDNA-matK-rbcL sequence data. American Journal of Botany 90, 1357-1372.
  6. ^ Eyde, R. H. (1988). Comprehending Cornus - puzzles and progress in the systematics of the dogwoods. Botanical Review 54, 233-351.

External links[edit]