Description from Flora of China
Shrubs, trees, or sometimes herbs, sometimes scrambling or scandent, sometimes armed, with aromatic volatile oils contained in glands visible at surface of at least leaves, young branchlets, inflorescences, flower parts, fruit, or cotyledons in seed. Stipules absent [or stipular excrescences rarely present]. Leaves alternate, opposite [or whorled], simple (petiole neither apically swollen nor articulate with leaf blade), 1-foliolate (in individual specimens at least some 1-foliolate leaves with petiole apically swollen and/or articulate with leaf blade), or variously compound. Flowers bisexual or unisexual, usually 3-5-merous, actinomorphic or rarely zygomorphic, hypogynous [or rarely perigynous]. Perianth in 2 series, with clearly differentiated calyx and corolla or sometimes in 2 irregular series or 1 series, with ± undifferentiated tepals. Sepals distinct or connate to their full length. Petals distinct [or rarely coherent or connate for part of their length]. Stamens usually as many as or 2 × as many as petals or sometimes more numerous; filaments distinct or sometimes coherent or connate for at least part of their length; anthers introrse or sometimes latrorse, longitudinally dehiscent. Disk [rarely lacking] within androecium, nectariferous, flattened, annular, cup-shaped, pulvinate, or sometimes columnar, bell-shaped, conic, or hourglass-shaped. Gynoecium of 1-5 distinct 1-loculed carpels or 2 to many partially to completely connate carpels; placentation axile [very rarely becoming parietal]; ovules 1 to many per locule. Fruit of 2-5 follicles [drupes or samaras] or a single follicle, capsule, or berry [or samara]. Seeds with relatively large embryo; endosperm present and fleshy or lacking.
Oil glands of Rutaceae, when viewed from the surface of plant parts they occupy, are usually pellucid. They also appear to be ± isodiametric and to have ± definite patterns of distribution. In blades of leaves, for example, where they are most commonly observed, they are usually ± evenly scattered throughout, or sometimes they are restricted to the margins. Rarely they are alleged to occur only along the secondary veins of the blades.
In a cladistic analysis of selected genera of Rutaceae and related families based on rbcL and atpB molecular data (but only on rbcL data for Harrisonia), M. W. Chase, C. M. Morton, and J. A. Kallunki (Amer. J. Bot. 86: 1191-1199. 1999) recommended the placement of Harrisonia (traditionally Simaroubaceae) in Rutaceae. We do not agree with this classification, particularly because Harrisonia appears to lack oil glands, and suggest that the genus is most correctly placed in Cneoraceae, in which it is treated herein.
Several taxa of cultivated Rutaceae treated by C. C. Huang (Fl. Reipubl. Popularis Sin. 43(3). 1997) are not treated here: Casimiroa edulis La Llave, which is native to Mexico, has been introduced as a cultivated plant to the Xishuangbanna Botanical Garden in Yunnan; Limonia acidissima Linnaeus (Feronia limonia (Linnaeus) Swingle), which is native to India and Sri Lanka, has been reported as cultivated in Taiwan by C. C. Huang (Fl. Reipubl. Popularis Sin. 44(3): 212. 1997) but was not reported as a cultivated plant by T. C. Huang in A Checklist of the Vascular Plants of Taiwan (Fl. Taiwan 6: 81-83. 1979); Flindersia amboinensis Poiret, which is native to Indonesia and New Guinea, is cultivated in S China; Ptelea trifoliata Linnaeus, which is native to North America, is cultivated in Beijing and Liaoning; and Ruta graveolens Linnaeus, which is native to the Mediterranean region, is widely cultivated in China.
Huang Chengchiu. 1997. Rutaceae. In: Huang Chengchiu, ed., Fl. Reipubl. Popularis Sin. 43(2): ii-viii, 1-250.
About 155 genera and ca. 1600 species: nearly cosmopolitan but mainly tropical and subtropical; 22 genera (one endemic, one introduced) and 126 species and hybrid species (49 endemic, at least two introduced) in China.
(Authors: Zhang Dianxiang (张奠湘); Thomas G. Hartley, David J. Mabberley)