Rutaceae

Taxonomy

Family name: Rutaceae Jussieu

Synonym(s): Amyridaceae Kunth; Aurantiaceae Juss.; Boroniaceae J. Agardh; Cneoraceae Vest, nom. cons.; Correaceae J. Agardh, nom. inval.; Cuspariaceae Tratt., nom. illeg.; Dictamnaceae Vest; Diosmaceae R. Br. ex Bartl.; Diplolaenaceae J. Agardh; Flindersiaceae C. T. White ex Airy Shaw; Fraxinellaceae Nees & Mart., nom. illeg.; Pilocarpaceae J. Agardh; Ptaeroxylaceae J.-F. Leroy; Pteleaceae Kunth; Zanthoxylaceae Martinov

Common name(s): rue or citrus family

*Number of genera/species: 176/2,070

List of genera records in GRIN-Global

Disseminule

fruit, fruit segment, or seed

Description

Fruit indehiscent berry (hesperidium), drupe, or samara, dehiscent loculicidal capsule, rarely septicidal, follicle (1–5 distinct or basally connate), or schizocarp splitting into drupelets, samaras, or follicle-like fruits, 2.5–150 mm long, globose to angular, terete or flattened in transection, often with stylar beak (Toddalioideae), sometimes winged (broad encompassing wing, winged at both ends, or terminal wing), 1- to many-seeded. Pericarp blue, black, purple, green, red, orange, yellow, or cream, in berries pulp color may differ from epicarp, texture variable, see below, glabrous or pubescent, smooth or gland-dotted, grooved, keeled, ribbed, warty (small to large warts), wrinkled, pitted, punctate, or with horns or prickles. Seeds sometimes explosively ejected.

Fruit type by subfamily

Aurantioideae: Berries, dry or fleshy with thick and hard or thin and leathery epicarp. The mesocarp is often differentiated into layers, which may be woody, fleshy, or mucilaginous. The endocarp is membranous, hard and woody, or soft or pulpy fleshy, sometimes becoming hard when dry. All fruits have a mucilaginous pulp surrounding seeds. In Citrus, the exocarp is thin and waxy. The mesocarp is often differentiated into three layers. The outermost layer is leathery with, often sunken, oil glands. The middle layer is thick and spongy, and the inner layer is white. Sometimes the mesocarp is woody. The endocarp is membranous and pulpy and/or resinous or gum-like.

Flindersioideae: Woody capsules.

Rutoideae: Thick-skinned and dry capsules or schizocarps or thick-skinned and fleshy berries.

Spathelioideae: Dry capsules and follicles or fleshy drupes or drupelets.

Toddalioideae: Berries, drupes, capsules, samaras, follicles, or schizocarps of drupes or follicle-like fruits. The epicarp in these may be dry, leathery, fleshy, woody, or membranous, mesocarp fleshy or woody, and endocarp often cartilaginous or undifferentiated.

Seed globose to irregular, sometimes with fold between cotyledons and hypocotyl-radicle or notched, raphe sometimes conspicuous, compressed or flattened in transection, 1.5–60 mm long. Apically and/or dorsally winged (Flindersioideae, Spathelioideae, some genera in Toddalioideae). Aril or elaiosome sometimes present, if present linear, fleshy, brown, yellow, or white, or vestigial aril (pellicle), red or black. Sometimes spongy-fleshy sarcotesta present.

Seed coat black, bluish black, purplish, brown, gray, green, red, yellow, or white, sometimes spotted or mottled, dull or shiny, glabrous or pubescent, leathery, scaly, fleshy (spongy), hard, papery, or membranous, glabrous or pubescent, sometimes densely so, smooth or grooved, ridged, wrinkled, warty, granular, reticulate, alveolate, bubbled, or papillate. Inner layer of seed coat often with thick, dense, black sclerenchyma. In Aurantioideae, seed coat fibrous and mucilaginous. Hilum often larger than punctate, linear, elliptic, or circular, short as or as long as seed, rarely a large cavity. In some genera, seed coat forms a subhilar rumination (bump or grove) near hilum.

Embryo well developed, completely to nearly completely filling seed coat, sometimes more than one per seed, relatively large, sometimes green, axile and centric, rarely peripheral (Cneoridium), foliate, linear, or elliptic, straight or curved, with spatulate or investing cotyledons. Cotyledons thin to thick, flat and folded. Endosperm copious, scanty, or absent, if copious, fleshy-soft or -hard, smooth.

For help identifying Citrus, see the Citrus ID tool.

Identification features

Fruit
Type	berry (hesperidium), drupe, samara, loculicidal capsule, rarely septicidal, follicle, or schizocarp splitting into drupelets or follicle-like fruits
Size range	2.5–150 mm long
Shape(s)	globose, ellipsoid, oblong, ovoid, cylindric, angular (pentagonous, cuboidal, quadrangular), pyriform, or rarely lobed, reniform, lunate or mitriform
Texture	leathery, woody, fleshy, chartaceous, membranous
Surface relief	smooth, gland-dotted, grooved, keeled, ribbed, warty (small to large warts), wrinkled, pitted, punctate, or with horns or prickles
Color(s)	blue, black, purple, green, red, orange, yellow, cream
Unique features	Fruits highly variable. Brightly colored berries with leathery rinds dotted with sunken oil glands and compressed or flattened mucilaginous seeds embedded in pulpy or resinous gummy-pulp are often encountered.
Seed
Size range	1.5–60 mm long
Shape(s)	globose, hemispherical, ellipsoid, lens-shaped, ovoid, pyriform, conical, wedge-shaped, tear-shaped, cuboidal, angled, reniform, irregular, U-shaped (Cneoridium)
Surface relief	smooth, grooved, ridged, wrinkled, warty, granular, reticulate, alveolate, bubbled, papillate
Color(s)	black, bluish black, purplish, brown, gray, green, red, yellow, or white, sometimes spotted or mottled
Unique features	Seeds often compressed or flattened with large, variously shaped hila and well developed, large, sometimes green embryos with thin to thick, flat and folded cotyledons, often embedded in endosperm. In some genera, more than one embryo per seed.
Other
Embryo	well developed, completely to nearly completely filling seed coat, sometimes more than one per seed, relatively large, sometimes green, axile and centric, rarely peripheral (Cneoridium), foliate, linear, or elliptic, straight or curved, with spatulate or investing cotyledons. Cotyledons thin to thick, flat and folded.
Nutritive tissue	endosperm copious, scanty, or absent, if copious, fleshy-soft or -hard, smooth

Distribution

Pantropical, also subtropical and warmer temperate regions.

Distribution map courtesy of Angiosperm Phylogeny Website.

References

Appelhans et al. 2021; Bayly et al. 2013; Cao et al. 2016; Choi et al. 2012; Duretto 1997; Duretto 2018; Flora of Australia 2021+; George 1971; Hartley 1977; Hartley 1986; Kirkbride et al. 2006; Kubitzki et al. 1990+; Meissner and Markey 2007; Mollemans 1993; Shelton and Thiele 2022; Takhtajan 2009; Wilson 1971; Zhengyi et al. 2004+

*The number of genera and species is based on Christenhusz and Byng 2016, which may differ from the number of genera in GRIN-Global.