The Cornales are an order of
flowering plants, early diverging among the
asterids, containing about 600 species. Plants within the Cornales usually have four-parted flowers,
drupaceous fruits, and inferior to half-inferior
gynoecia
Gynoecium (; ) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl of a flower; it consists of (one or more) ''pistils'' ...
topped with disc-shaped
nectar
Nectar is a sugar-rich liquid produced by plants in glands called nectaries or nectarines, either within the flowers with which it attracts pollinating animals, or by extrafloral nectaries, which provide a nutrient source to animal mutualists ...
ies.
Taxonomy
In the classification system of
Dahlgren the Cornales were in the
superorder
Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and ...
Corniflorae (also called Cornanae). Under the
APG IV system, the Cornales order includes these families:
*
Cornaceae (the
dogwood family)
*
Curtisiaceae (cape lancewood)
*
Grubbiaceae (the
sillyberry family)
*
Hydrangeaceae (the
hydrangea family)
*
Hydrostachyaceae
*
Loasaceae (the
stickleaf family)
*
Nyssaceae, (the
tupelos)
The oldest fossils assigned with confidence to the order are ''
Hironoia fusiformis'', described from
Coniacian
The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series and spans the time between 89.8 ± 1 Ma and 86.3 ± 0.7 Ma (million years ago). The Coniacian is preceded by t ...
age Japanese coalified fruits, and ''
Suciacarpa starrii
''Suciacarpa'' is an extinct genus of asterid flowering plants in the order Cornales. It is known from the fossil species ''Suciacarpa starrii'' and ''Suciacarpa xiangae'', both found in Western North America.
History and classification
''Suciac ...
'' described from American
permineralized
Permineralization is a process of fossilization of bones and tissues in which mineral deposits form internal casts of organisms. Carried by water, these minerals fill the spaces within organic tissue. Because of the nature of the casts, perminera ...
fruits of
Campanian age.
Phylogeny
The Cornales order is sister to the remainder of the large and diverse
asterid clade
A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...
.
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.
[Xiang, Q. Y., ]Soltis, D. E.
Douglas Soltis is a Distinguished Professor in the Laboratory of Molecular Systematics & Evolutionary Genetics, (Soltis lab.) Florida Museum of Natural History and Department of Biology at the University of Florida. His research interests are in ...
, Morgan, D. R., and Soltis, P. S.
Pamela Soltis (born November 13, 1957) is an American botanist. She is a distinguished professor at the University of Florida, curator at the Florida Museum of Natural History, principal investigator of the Laboratory of Molecular Systematics an ...
(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. 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
''Griselinia'' is a genus of seven species of shrubs and trees, with a highly disjunct distribution native to New Zealand and South America. It is a classic example of the Antarctic flora. It is the sole genus in the family Griseliniaceae; in th ...
'', ''
Corokia'', and ''
Kaliphora
''Kaliphora madagascarensis'' is a species of evergreen shrub or small tree. It is endemic to Madagascar, where it inhabits subhumid woodlands and forests in eastern Madagascar, in the provinces of Antananarivo, Antsiranana, Fianarantsoa, and M ...
'', among others.
Likely cladogram for Cornales:
[Based on Figure 11.10 in ]
Molecular data suggest four clades are within the Cornales: ''
Cornus-
Alangium'',
nyssoids-mastixioids, Hydrangeaceae-Loasaceae, and ''
Grubbia
''Grubbia'' is a genus of flowering plants in the family Grubbiaceae.Vernon H. Heywood, Richard K. Brummitt, Ole Seberg, and Alastair Culham. 2007. ''Flowering Plant Families of the World''. Firefly Books: Ontario, Canada. . The genus has three s ...
-
Curtisia'', with the Hydrostachyaceae in an uncertain position, possibly basal.
[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.] 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.
[Eyde, R. H. (1988). Comprehending ''Cornus'' - puzzles and progress in the systematics of the dogwoods. ''Botanical Review'' 54, 233-351.] These difficulties in interpreting the systematics of Cornales may represent an early and rapid diversification of the groups within the order.
References
External links
* http://www.britannica.com/EBchecked/topic/137865/Cornales
{{Taxonbar, from=Q21769
Angiosperm orders