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Cornales

(Order)

Overview

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Cornales is an order of flowering plants, basal among the asterids, containing about 600 species. Plants within Cornales usually have four-parted flowers, drupaceous fruits, and inferior gynoecia topped with disc-shaped nectaries. Under the APG system, Cornales includes the following families:

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Cornales is sister to the remainder of the large and diverse asterid clade.

Members of 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.[1] 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 Cornales have been removed, including Garryaceae, Griselinia, Corokia, and Kaliphora, among others.[1]

Molecular data suggest that there are four clades within the Cornales: Cornus-Alangium, nyssoids-mastixioids, Hydrangeaceae-Loasaceae, and Grubbia-Curtisia, with Hydrostachyaceae in an uncertain position, possibly basal.[2] 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.[1][2][3] These difficulties in interpreting the systematics of Cornales may represent an early and rapid diversification of the groups within the order.[2]

reviously associated with Cornales have been removed, including Garryaceae, Griselinia, Corokia, and Kaliphora, among others.[1]

Molecular data suggest that there are four clades within the Cornales: Cornus-Alangium, nyssoids-mastixioids, Hydrangeaceae-Loasaceae, and Grubbia-Curtisia, with Hydrostachyaceae in an uncertain position, possibly basal.[2] 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.[1][2][3] These difficulties in interpreting the systematics of Cornales may represent an early and rapid diversification of the groups within the order.[2]

References

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  1. ^ 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.
  2. ^ 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.
  3. ^ Eyde, R. H. (1988). Comprehending Cornus - puzzles and progress in the systematics of the dogwoods. Botanical Review 54, 233-351.

External links

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http://www.britannica.com/EBchecked/topic/137865/Cornales

Taxonomy

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The Order Cornales is further organized into finer groupings including:

Families

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Alangiaceae

Alangiaceae is a small family of small dicotyledon trees, shrubs or lianas, closely related to the Cornaceae (Dogwood family). [more]

Cornaceae

Cornaceae (the dogwood family) is a cosmopolitan family of flowering plants in the order Cornales. It contains approximately 110 species, mostly trees and shrubs, which may be deciduous or evergreen. Members of this family usually have opposite or alternate simple leaves, four- or five-parted flowers clustered in inflorescences or pseudanthia, and drupaceous fruits. In northern temperate areas, Cornaceae is well known from two genera: Cornus, the dogwoods, and Nyssa, the tupelos. [more]

Curtisiaceae

Curtisia dentata (commonly known as the Assegai tree, Umlahleni or Cape Lancewood) is a flowering tree from Southern Africa. It is the sole species in genus Curtisia, which was originally classed as a type of "Dogwood" (Cornaceae), but is now placed in its own unique family Curtisiaceae. It is increasingly popular as an ornamental tree for gardens, with dark glossy foliage and sprays of pure white berries. [more]

Davidiaceae

[more]

Grubbiaceae

[more]

Hydrangeaceae

Hydrangeaceae are a family of flowering plants in the order Cornales, with a wide distribution in Asia and North America, and locally in southeastern Europe. [more]

Hydrostachyaceae

[more]

Loasaceae

The Loasaceae is a family of 15-20 genera and about 200-260 species of flowering plants in the order Cornales, native to the Americas and Africa. The family comprises annual, biennial and perennial herbaceous plants, and a few shrubs and small trees. [more]

Mastixiaceae

Trees evergreen, resinous. Leaves opposite or alternate, petiolate, estipulate, simple, margin entire or rarely undulate, leathery to thickly papery, often pubescent with unicellular 2-armed trichomes, pinnately veined. Inflorescences paniculate cymes, terminal and axillary. Flowers bisexual, actinomorphic, 4- or 5-merous. Petals distinct, valvate. Anthers dorsifixed, dehiscing via longitudinal slits; pollen 3-aperturate. Ovary inferior, carpel 1, locule 1; ovule 1, pendulous; disk epigynous, fleshy; style 1, stigma punctiform, unlobed, or lobes slight, 2, 4, or 5. Fruit drupes, fleshy, or hard when dry; endocarp grooved; seed 1, endosperm fleshy; cotyledons 2, leafy; embryo small.[1] [more]

Nyssaceae

Nyssaceae is a small family of flowering trees closely related to and often included within the dogwood family (Cornaceae). Nyssaceae commonly includes the following genera: [more]

At least 176 species and subspecies belong to the Family Nyssaceae.

More info about the Family Nyssaceae may be found here.

References

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  1. ^ 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.
  2. ^ 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.
  3. ^ Eyde, R. H. (1988). Comprehending Cornus - puzzles and progress in the systematics of the dogwoods. Botanical Review 54, 233-351.

Bibliography

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Footnotes

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  1. Jenny Qiuyun Xiang, Qibai Xiang, David E. Boufford & Porter P. Lowry "Mastixiaceae". in Flora of China Vol. 14 Page 230. Published by Science Press (Beijing) and Missouri Botanical Garden Press. Online at EFloras.org.

Sources

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Last Revised: August 24, 2012
2012/08/24 13:10:21