Fossil rosids are known from the
Cretaceous period.
Molecular clock estimates indicate that the rosids originated in the
Aptian or
Albian stages of the Cretaceous, between 125 and 99.6 million years ago.[5][6]
Today's forests are highly dominated by rosid species, which in turn helped with diversification in many other living lineages. Additionally, rosid herbs and shrubs are also a significant part of arctic/alpine, temperate floras, aquatics, desert plants, and parasites.[7]
Name
The name is based upon the name "
Rosidae", which had usually been understood to be a subclass. In 1967,
Armen Takhtajan showed that the correct basis for the name "Rosidae" is a description of a
group of plants published in 1830 by
Friedrich Gottlieb Bartling.[8] The clade was later renamed "Rosidae" and has been variously
delimited by different authors. The name "rosids" is informal and not assumed to have any particular
taxonomic rank like the names authorized by the
ICBN. The rosids are
monophyletic based upon evidence found by
molecular phylogenetic analysis.
Three different
definitions of the rosids were used. Some authors included the orders
Saxifragales and
Vitales in the rosids.[9] Others excluded both of these orders.[10] The circumscription used in this article is that of the
APG IV classification, which includes Vitales, but excludes Saxifragales.
The rosids consist of two groups: the order Vitales and the eurosids (true rosids).
The eurosids, in turn, are divided into two groups: fabids (Fabidae, eurosids I) and malvids (Malvidae, eurosids II).[10]
Orders
The rosids consist of 17 orders. In addition to Vitales, there are eight orders in fabids and eight orders in malvids. Some of the orders have only recently been recognized.[10] These are Vitales,[12] Zygophyllales,[13] Crossosomatales,[14] Picramniales,[15] and Huerteales.[16]
The nitrogen-fixing clade contains a high number of
actinorhizal plants (which have root nodules containing
nitrogen fixing bacteria, helping the plant grow in poor soils). Not all plants in this clade are actinorhizal, however.[17]
^Scotland, Robert W.; Wortley, Alexandra H. (2003), "How many species of seed plants are there?", Taxon, 52 (1): 101–4,
doi:
10.2307/3647306,
JSTOR3647306
^Soltis, Douglas E.; Soltis, Pamela S.; Peter K. Endress;
Mark W. Chase (2005), Phylogeny and Evolution of the Angiosperms, Sunderland, MA, USA: Sinauer,
ISBN978-0-87893-817-9
^Burleigh, J. Gordon; Hilu, Khidir W.; Soltis, Douglas E. (2009), File 7, "Inferring phylogenies with incomplete data sets: a 5-gene, 567-taxon analysis of angiosperms", BMC Evolutionary Biology, 9: 61,
doi:
10.1186/1471-2148-9-61,
PMC2674047,
PMID19292928
^Chalk, L. (1983), "Wood structure", in Metcalfe, C.R.; Chalk, L. (eds.), Wood Structure and Conclusion of the General Introduction, Anatomy of the Dicotyledons, vol. II (2nd ed.), Clarendon Press, pp. 1-51 [1-2 by C. R. Melcalfe],
ISBN978-0-19-854559-0
^Hutchinson, John (1979) [1973], The Families of Flowering Plants (3rd ed.), Oxford University Press,
ISBN9783874291606
^Worberg, Andreas; Alford, Mac H.; Quandt, Dietmar; Borsch, Thomas (2009), "Huerteales sister to Brassicales plus Malvales, and newly circumscribed to include Dipentodon, Gerrardina, Huertea, Perrottetia, and Tapiscia", Taxon, 58 (2): 468–478,
doi:
10.1002/tax.582012