The Families of Flowering Plants

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L. Watson and M. J. Dallwitz

Rutaceae Juss.

Including Amyrideae (Amyridaceae) R. Brown, Aurantiaceae Juss., Boroniaceae J.G. Agardh, Correaceae J.G. Agardh, Cuspariaceae J.G. Agardh, Dictamnaceae von Vest, Diosmeae (Diosmaceae) R. Br., Diplolaenaceae J.G. Agardh, Fraxinellae, (Fraxinellaceae) Nees & Mart., Pilocarpeae, (Pilocarpaceae) J.G. Agardh, Pteleaceae Kunth, Sarcodiscaceae Dulac, Zanthoxylaceae Nees & Mart. corr. Bartl.

Excluding Flindersiaceae, Rhabdodendraceae

Habit and leaf form. Trees and shrubs (mostly), or herbs (Rutieae); bearing essential oils. ‘Normal’ plants, or switch-plants (sometimes with spines); sometimes with the principal photosynthesizing function transferred to stems, or phyllodineous. Leaves well developed, or much reduced. Plants autotrophic. Mesophytic, or xerophytic. Leaves evergreen, or deciduous; alternate, or opposite; usually spiral; ‘herbaceous’, or leathery; petiolate; non-sheathing; nearly always gland-dotted (exceptions: Leptothyrsa, Phellodendron); aromatic; simple, or compound (usually); when compound (i.e. usually) ternate, or pinnate, or bipinnate, or unifoliolate. Lamina when simple dissected, or entire; sometimes linear (and ericoid); when simple/dissected pinnatifid, or much-divided; pinnately veined, or one-veined. Leaves exstipulate (usually), or stipulate (rarely). Stipules when present, intrapetiolar; represented by glands. Leaves without a persistent basal meristem. Domatia occurring in the family (from 3 genera); manifested as pockets.

Leaf anatomy. Extra-floral nectaries seemingly absent. Mucilaginous epidermis present, or absent.

Lamina with secretory cavities. Secretory cavities containing oil; Secretory cavities schizogenous, or lysigenous. The mesophyll without etherial oil cells; with sclerencymatous idioblasts, or without sclerenchymatous idioblasts. Minor leaf veins without phloem transfer cells (5 genera).

Stem anatomy. Secretory cavities present; with oil. Cork cambium present; initially superficial. Nodes unilacunar, or tri-lacunar. Internal phloem absent. Secondary thickening developing from a conventional cambial ring. ‘Included’ phloem absent. Xylem with libriform fibres; with vessels. Vessel end-walls simple. Vessels without vestured pits. Wood storied (Chloroxylon), or partially storied (?), or not storied (?); parenchyma apotracheal, or paratracheal (rarely absent).

Reproductive type, pollination. Plants hermaphrodite (usually), or monoecious, or andromonoecious (rarely), or dioecious, or polygamomonoecious. Pollination entomophilous.

Inflorescence, floral, fruit and seed morphology. Flowers solitary (rarely), or aggregated in ‘inflorescences’; in cymes, in panicles, in racemes, and in corymbs. The terminal inflorescence unit cymose (usually), or racemose. Inflorescences terminal, or axillary, or epiphyllous (rarely). Flowers bracteate; small to medium-sized; commonly fragrant; regular (usually), or somewhat irregular. The floral irregularity when noticeable, involving the perianth and involving the androecium (not K). Flowers mostly (3–)5 merous; cyclic. Floral receptacle developing a gynophore (associated with the disk), or with neither androphore nor gynophore. Free hypanthium absent. Hypogynous disk present; intrastaminal; annular (sometimes one-sided), or of separate members (e.g. in Coleonema).

Perianth with distinct calyx and corolla (but the calyx sometimes minute and inconspicuous); (3–)6, or (6–)10; 2 whorled; isomerous. Calyx (3–)4, or 5; 1 whorled; polysepalous, or gamosepalous (basally); regular; imbricate, or valvate (e.g. Boronia, Correa); with the median member posterior. Corolla (3–)4, or 5; 1 whorled; polypetalous, or gamopetalous; imbricate, or valvate (the odd member anterior); regular, or unequal but not bilabiate.

Androecium 2, or 3, or 5, or 8, or 10, or 20–60. Androecial members unbranched, or branched (by the splitting of simple primordia, e.g. in Citrus); free of the perianth; all equal, or markedly unequal; free of one another, or coherent (the filaments usually more or less basally connate); 1 adelphous, or 3–12 adelphous (‘polyadelphous’ in Citrus); 1 whorled, or 2 whorled. Androecium exclusively of fertile stamens, or including staminodes. Staminodes (often representing the antepetalous whorl) (3–)4, or 5(–10); external to the fertile stamens. Stamens 2–60; reduced in number relative to the adjacent perianth to polystemonous; alternisepalous, or oppositisepalous (when the outer whorl lost); alternating with the corolla members, or both alternating with and opposite the corolla members. Anthers dorsifixed, or basifixed (more or less, e.g.Erythrochiton, Melicope); not becoming inverted during development; versatile; dehiscing via longitudinal slits; introrse (usually), or latrorse (more or less, e.g. Dictamnus); tetrasporangiate; unappendaged. Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or isobilateral, or decussate. Anther wall initially with more than one middle layer (2 or 3). Tapetum glandular. Pollen grains aperturate; (2–)3–6(–8) aperturate; colporate; 2-celled, or 3-celled.

Gynoecium (1–)3 carpelled (rarely), or 4–5(–100) carpelled (rarely ‘many’, e.g. in Citrus). The pistil when syncarpous, (1–)4–5(–100) celled (to ‘many’). Gynoecium apocarpous to syncarpous; eu-apocarpous, or synstylous, or semicarpous to synovarious (the carpels commonly more or less united basally or at the sides), or synstylovarious to eu-syncarpous (in the Aurantioideae); superior (most commonly), or partly inferior (Platyspermation), or inferior (Aurantioideae). Carpel (when apo- or semicarpous) (1–)2–100 ovuled (i.e. to many). Placentation of the free carpels marginal. Ovary when syncarpous, (1–)4–5(–100) locular (i.e. sometimes ‘many’). Styles 1, or 3–5; free, or partially joined; apical. Stigmas wet type, or dry type; papillate, or non-papillate; Group II type, or Group IV type. Placentation when syncarpous, axile. Ovules 1–5(–50) per locule (i.e. to many); pendulous to ascending; epitropous (the micropyle facing upwards, the raphe sometimes branching); always with ventral raphe; when two or more per cell, collateral, or superposed, or biseriate; arillate, or non-arillate; anatropous, or hemianatropous; bitegmic, or unitegmic (rarely); crassinucellate. Outer integument usually contributing to the micropyle, or not contributing to the micropyle (rarely). Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids sometimes hooked (and sometimes with filiform apparatus). Hypostase usually present. Endosperm formation nuclear. Endosperm haustoria present, or absent; chalazal (aggressive, in Aegle). Embryogeny onagrad, or solanad.

Fruit fleshy, or non-fleshy; an aggregate, or not an aggregate. The fruiting carpels coalescing into a secondary syncarp, or not coalescing. The fruiting carpel dehiscent, or indehiscent; (when apocarpous) a follicle, or drupaceous, or baccate. Fruit (when syncarpous) dehiscent, or indehiscent, or a schizocarp. Mericarps when schizocarpic, 2–5(–100) (?); comprising berrylets, or comprising follicles, or comprising nutlets, or comprising drupelets. Fruit when syncarpous and non-schizocarpic, a berry (often in the form of a hesperidium), or a drupe, or a samara; without fleshy investment. Seeds endospermic, or non-endospermic. Embryo well differentiated. Cotyledons 2; flat, or folded, or rolled. Embryo chlorophyllous (6/17), or achlorophyllous (3/7); straight, or curved, or bent. Polyembryony recorded (common in Citrus).

Seedling. Germination phanerocotylar, or cryptocotylar.

Physiology, biochemistry. Cyanogenic (rarely), or not cyanogenic. Cynogenic constituents phenylalanine-derived. Alkaloids present (commonly), or absent. Iridoids not detected. Arthroquinones detected (6 genera); derived from shikimic acid (doubtfully, Clausena), or polyacetate derived (the rest). Proanthocyanidins present, or absent; when present, cyanidin, or cyanidin and delphinidin. Flavonols present (mostly), or absent (e.g. Eriostemon, Aurantioideae); kaempferol and quercetin, or kaempferol, quercetin, and myricetin. Ellagic acid absent (14 species, 13 genera). Arbutin absent. Saponins/sapogenins present (seldom), or absent. Aluminium accumulation not found. Sugars transported as oligosaccharides + sucrose (in most material sampled), or as sucrose, or as sugar alcohols + oligosaccharides + sucrose. C3. C3 physiology recorded directly in Citrus, Fortunella, Ruta, Zanthoxylum. Anatomy non-C4 type (Citrus, Haplophyllum).

Geography, cytology. Temperate, sub-tropical, and tropical. Pantropical and subtropical, and widespread temperate. X = 7–11(+). Supposed basic chromosome number of family: 9.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Rutiflorae; Rutales. Cronquist’s Subclass Rosidae; Sapindales. APG (1998) Eudicot; core Eudicot; Rosid; Eurosid II; Sapindales. Species 900. Genera about 150; Acmadenia, Acradenia, Acronychia, Adenandra, Adiscanthus, Aegle, Aeglopsis, Afraegle, Agathosma, Almeidea, Amyris, Angostura, Apocaulon, Araliopsis, Asterolasia, Atalantia, Balfourodendron, Balsomocitrus, Bergera, Boenninghausenia, Boninia, Boronia, Bosistoa, Bouchardatia, Bouzetia, Brombya, Burkillanthus, Calodendrum, Casimiroa, Choisya, Chorilaena, Citropsis, Citrus, Clausena, Clymenia, Cneoridium, Coleonema, Comptonella, Correa, Crowea, Cusparia, Decagonocarpus, Decatropis, Decazyx, Dictamnus, Dictyoloma, Diosma, Diphasia, Diphasiopsis, Diplolaena, Drummondita, Dutaillyea, Empleurum, Eremocitrus, Eriostemon, Erythrochiton, Esenbeckia, Euchaetis, Euodia, Euxylophora, Evodiella, Fagaria, Fagaropsis, Feronia, Feroniella, Fortunella, Galipea, Geijera, Geleznowia, Glycosmis, Halfordia, Haplophyllum, Helietta, Hortia, Ivodea, Kodalyodendron, Leptothyrsa, Limnocitrus, Limonia, Lubaria, Lunasia, Luvunga, Maclurodendron, Macrostylis, Medicosma, Megastigma, Melicope, Merope, Merrillia, Metrodorea, Microcitrus, Microcybe, Micromelum, Monanthocitrus, Monnieria, Muiriantha, Murraya, Myrtopsis, Naringi, Naudinia, Nematolepis, Neobyrnesia, Neoraputia, Nycticalanthus, Oricia, Oriciopsis, Orixa, Oxanthera, Pamburus, Paramignya, Peltostigma, Pentaceras, Phebalium, Phellodendron, Philotheca, Phyllosma, Pilocarpus, Pitavia, Platydesma, Pleiospermium, Plethadenia, Polyaster, Poncirus, Pseudiosma, Psilopeganum, Ptelea, Raputia, Raputiarana, Rauia, Raulinosa, Ravenia, Raveniopsis, Rhadinothamnus, Ruta, Rutaneblina, Sarcomelicope, Sargentia, Severinia, Sheilanthera, Sigmatanthus, Skimmia, Spathelia, Spiranthera, Stauranthus, Swinglea, Teclea, Tetractomia, Tetradium, Thamnosma, Ticorea, Toddalia, Toddaliopsis, Tractocopevodia, Triphasia, Vepris, Wenzelia, Zanthoxylum, Zieria, Zieridium.

Economic uses, etc. Many edible fruits from Citrus spp., Aegle, Casimiroa, Clausena etc. (orange, lemon, lime, grapefruit, citron, Bengal quince or bael fruit, casimiroa or white sapote, wampee, etc.); several are or have been officinal (Ruta, Galipea, Toddalia, chiefly on account of their oils).

Illustrations. • Technical details (Dictamnus, Thamnosma). • Technical details (Ruta graveolens). • Technical details (Citrus, Murraya). • Technical details (Diosma). • Technical details (Zanthoxylum). • Technical details, from Lindley (Toddalia). • Technical details, from Thonner (Agathosma).

Quotations

A lemon
Stuck with cloves
(‘Love’s Labour’s Lost’, v., 2)

The juice, with vinegar, given to smell unto, doth revive and quicken such as have the forgetful sicknesse
(Lyte, of Ruta graveolens)


This description is offered for casual browsing only. We strongly advise against extracting comparative information from it. This is much more easily achieved using the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting specified attributes, summaries of attributes within groups of taxa, geographical distribution, genera included in each family, classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG), and notes on the APG classification.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 10th April 2008. http://delta-intkey.com’.

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