Rutaceae, commonly known as the rue^[3] or citrus family,^[4] is a family of flowering plants, usually placed in the order Sapindales.

Species of the family generally have flowers that divide into four or five parts, usually with strong scents. They range in form and size from herbs to shrubs and small trees.

The most economically important genus in the family is Citrus, which includes the orange (C. sinensis), lemon (C. × limon), grapefruit (C. paradisi), and lime (various, mostly C. aurantifolia, the key lime). Boronia is a large Australian genus, some members of which are plants with highly fragrant flowers and are used in commercial oil production. Other large genera include Zanthoxylum, Melicope and Agathosma. There are approximatively 160 genera in the family Rutaceae:List of Rutaceae genera

Characteristics

Most species are trees or shrubs, a few are herbs (Boenninghausenia), frequently aromatic with glands on the leaves, sometimes with thorns. The leaves are usually opposed and compound, and without stipules. Pellucid glands, a type of oil containing cavities, are found on the leaves responsible for the aromatic smell of the family's members; traditionally they have been the primary synapomorphic characteristic to identify the Rutaceae.

Flowers are bractless, solitary or in cyme, rarely in raceme, and mainly pollinated by insects. They are radially or (rarely) laterally symmetric, and generally hermaphroditic. They have four or five petals and sepals, sometimes three, mostly separate, eight to ten stamen (five in Skimmia, many in Citrus), usually separate or in several groups. Usually a single stigma with 2 to 5 united carpels, sometimes ovaries separate but styles combined.

The fruit of Rutaceae are very variable: berries, drupes, hesperidiums, samaras, capsules and follicles all occur. Seed number also varies widely.

Classification

The family is closely related to Sapindaceae, Simaroubaceae and Meliaceae, and all are usually placed into the same order, although some systems separate that order into Rutales and Sapindales. The families Flindersiaceae and Ptaeroxylaceae are sometimes kept separate, but nowadays generally placed in Rutaceae, as are the former Cneoraceae. The subfamilial organization has not been fully resolved, but the subfamilies Aurantioideae (=Citroideae) and Rutoideae are well supported; the placement of several genera remains unclear.

Notable species

various Citrus fruits

The family is of great economic importance in warm temperate and sub-tropical climates for its numerous edible fruits of the Citrus genus, such as the orange, lemon, lime, kumquat, mandarin and grapefruit. Non-citrus fruits include the White sapote (Casimiroa edulis), Orangeberry (Glycosmis pentaphylla), Clymenia (Clymenia polyandra), Limeberry (Triphasia trifolia), and the Bael (Aegle marmelos). Other plants are grown in horticulture: Murraya species, for example. Ruta, Zanthoxylum and Casimiroa species are medicinals. Several plants are also used by the perfume industry, such as the Western Australian Boronia megastigma.

The genus Pilocarpus has species (P. jaborandi, and P. microphyllus from Brazil, and P. pennatifolius from Paraguay) from which the medicine pilocarpine, used to treat glaucoma, is extracted.

Spices are made from a number of species in the genus Zanthoxylum, notably Sichuan pepper.

References

• Singh, Gurjaran (2004). Plant Systematics: An Integrated Approach. Enfield, New Hampshire: Science Publishers. pp. 438–440. ISBN 1-57808-342-7. 
• Chase, Mark W.; Cynthia M. Morton & Jacquelyn A. Kallunki (August 1999). "Phylogenetic relationships of Rutaceae: a cladistic analysis of the subfamilies using evidence from RBC and ATP sequence variation". American Journal of Botany (Botanical Society of America) 86 (8): 1191–1199. doi:10.2307/2656983. JSTOR 2656983. PMID 10449399. http://www.amjbot.org/cgi/content/full/86/8/1191. Retrieved 2007-08-30. 

Ptaeroxylaceae is a small subfamily of Southern African indigenous trees and woody lianes, most of them from Madagascar, within the rue and citrus family (Rutaceae), comprising only two genera ^[2] .

Genus: Cedrelopsis ^[3] Baill.

Species:

Genus: Ptaeroxylon Ecklon & Zeyher, 1834 ^[4]

• Ptaeroxylon obliquum (Thunb.) Radlk. (Ptaeroxylon utile)

References

Cneoraceae is a Mediterranean relict shrub family that evolved under tropical conditions during the Tertiary age. It is a dicot that generally favours higher altitudes and is rich in tannin. It produces both hermaphrodite and male flowers but the male flowers produce more fertile pollen, leading to a fruit.^[2]

There are two genera and six species in tropical Africa, South and Southeast Asia, northern Australia, the Canary Islands, the northwestern Mediterranean, Cuba and China.

References