(botany) A large subclass of the class Magnoliatae; most have a well-developed corolla with petals separate from each other, binucleate pollen, and ovules usually with two integuments.
Rosidae
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(′rōz·ə′dē)
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A former widely recognized subclass of Magnoliophyta (angiosperms or flowering plants). Deoxyribonucleic acid (DNA) and morphological studies have demonstrated that this group includes many more families than previously thought. Approximately 136 families (roughly 30% of the total angiosperms) in 11 orders are included in the rosids. With the asterids (often recognized as Asteridae), the rosids represent the two most advanced lines of dicots.
The primary distinguishing features of rosids are their diplostemenous flowers (anthers in two whorls, each whorl typically numbering the same as the perianth parts, although in some groups the number of stamens has increased) with unfused parts, except for the carpels (asterids have haplostemenous flowers with fused parts, typically with the stamens fused at least to the bases of the petals). Rosids have ovules with two integuments (that is, they are bitegmic, as opposed to the unitegmic asterids) and a several-layered nucellus (that is, they are crassinucellate, as opposed to the tenuinucellate asterids, which have a single-layered nucellus). There is nuclear endosperm formation (cellular in asterids), a reticulate pollen layer, mucilaginous leaf epidermis, and generally simple perforation vessel end-walls in the wood. The largest rosid orders are Malpighiales (16,100 species), Fabales (17,500), and Myrtales (10,600). See also Apiales; Celastrales; Cornales; Euphorbiales; Fabales; Geraniales; Haloragales; Linales; Magnoliopsida; Myrtales; Podostemales; Polygalales; Proteales; Rafflesiales; Rhizophorales; Rosales; Santalales; Sapindales.
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Note: click on a word meaning below to see its connections and related words.
The noun has one meaning:
Meaning #1:
a group of trees and shrubs and herbs mostly with polypetalous flowers; contains 108 families including Rosaceae; Crassulaceae; Myrtaceae; Melastomaceae; Euphorbiaceae; Umbelliferae
Synonym: subclass Rosidae
| Wikipedia: Rosidae |
Under the International Code of Botanical Nomenclature (ICBN) Rosidae is a botanical name at the rank of subclass. Circumscription of the subclass will vary with the taxonomic system being used; the only requirement being that it includes the family Rosaceae.
Under Phylocode Rosidae is a clade defined as the most inclusive crown clade containing Rosa cinnamomea[1] but not Berberidopsis corallina nor Dillenia indica nor Gunnera manicata nor Helianthus annuus nor Saxifraga mertensiana nor Stellaria media nor Viscum album. [2]
A well-known usage of the former sense is in the Cronquist system; in the 1981, original, version of that system the circumscription was:
- subclass Rosidae
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The Phylocode definition includes Crossosomatales, Geraniales, Myrtales, Fabidae (Celastrales, Cucurbitales, Fabales, Fagales, Huaceae, Oxalidales, Malpighiales, Rosales and Zygophyllales), Malvidae (Brassicales, Dipentodontaceae, Gerrardinaceae, Malvales, Sapindales, and Tapisciaceae), "probably" Picramniaceae, and "possibly" Vitaceae.[2]
There is considerable overlap between two definitions (some apparent differences are the result of the use of more broadly drawn orders in the second), but Apiales, Cornales, Proteales and Santales and parts of Rafflesiales are excluded from the second, and many groups from Cronquist's Hamamelidae and Dillenidae are included.
In both senses the term "rosid" applies, as an adjective and noun, to members of the group. In the APG and APG II systems, which eschewed formal formal botanical names between the ranks of class and order the term "rosids" is used to define an informal clade corresponding to the PhyloCode (Cantino et al.) sense.
References
- ^ sensu L. 1753 non L. 1759
- ^ a b Cantino, Philip D.; James A. Doyle, Sean W. Graham, Walter S. Judd, Richard G. Olmstead, Douglas E. Soltis, Pamela S. Soltis, & Michael J. Donoghue (2007). "Towards a phylogenetic nomenclature of Tracheophyta". Taxon 56 (3): E1–E44. http://www.ingentaconnect.com/content/iapt/tax/2007/00000056/00000003/art00020.
External links
Rosidae at the TAMU Lab
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 | Rosales (botany) |
| Celastrales (botany) |
| Cornales (botany) |
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Mentioned in
- Rosales (botany)
- Celastrales (botany)
- Cornales (botany)
- Euphorbiales (botany)
- Geraniales (botany)
- Myrtales (botany)
- Polygalales (botany)
- Santalales (botany)
- Podostemales (magnoliophyta)
- Haloragales (botany)
- Proteales (botany)
- Sapindales (botany)
- Rhamnales (botany)
- Umbellales (botany)
