The families of flowering plants

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L. Watson and M. J. Dallwitz

Rubiaceae Juss.

Including Aparineae (Aparinaceae) Hoffmgg. & Link, Dialypetalanthaceae, Cinchonaceae Lindl., Coffeaceae J.G. Agardh, Galiaceae Lindley, Gardeniaceae Dum., Lippayaceae Meissner, Lygodysodeaceae Bartl., Operculariaceae Dum.; excluding Henriqueziaceae, Naucleaceae.

Habit and leaf form. Trees and shrubs (mostly), or lianas, or herbs (then mostly with tetragonous, knotted stems); non-laticiferous. Plants non-succulent. Self supporting, or epiphytic, or climbing. Helophytic, or mesophytic, or xerophytic, or hydrophytic (Limnosipanea). Leaves opposite (nearly always, and decussate), or whorled (or at least ostensibly so, seemingly representing paired leaves with enlarged, leaflike interpetiolar stipules — and rarely ostensibly alternate, through suppression of one member of each pair); ‘herbaceous’, or leathery; petiolate to sessile; connate (often, via the stipules), or not connate; gland-dotted, or not gland-dotted; simple; epulvinate. Lamina entire; one-veined, or pinnately veined; cross-venulate. Leaves stipulate. Stipules interpetiolar (usually), or intrapetiolar; with colleters (typically). Lamina margins entire, or serrate. Leaf development not ‘graminaceous’. Domatia occurring in the family (widespread, but not universal); manifested as pits (mostly), or pockets, or hair tufts.

General anatomy. Plants with ‘crystal sand’ (very commonly, in leaves and axes), or without ‘crystal sand’.

Leaf anatomy. The leaf lamina dorsiventral (nearly always), or centric (rarely). Stomata mainly confined to one surface (abaxial, usually), or on both surfaces (in assorted species). Hairs present; exclusively eglandular; unicellular, or multicellular (often septate in Rubioideae, not septate in Cinchonoideae and Guettardoideae). Unicellular hairs simple. Multicellular hairs uniseriate. Complex hairs present, or absent; when present, tufted or peltate. Adaxial hypodermis present, or absent. Lamina with secretory cavities, or without secretory cavities (more often containing secretory cells, contents mostly unidentified but sometimes resinous). Secretory cavities when present, lysigenous. The mesophyll with sclerenchymatous idioblasts (sometimes), or without sclerenchymatous idioblasts; containing crystals (usually), or without crystals. The crystals raphides, or druses, or solitary-prismatic (raphides present in Rubioideae, absent from Cinchonoideae and Guettardoideae). Minor leaf veins with phloem transfer cells (5 genera — Asperula, Galium, Phuopsis, Rubia, Sherardia), or without phloem transfer cells (20 genera, e.g. Coprosma, Cinchona, Coffea, Gardenia, Hoffmannia, Ixora, Pavetta, Randia).

Axial (stem, wood) anatomy. Young stems commonly polygonal or corrugated in section. Cork cambium present, or absent (e.g. in Galieae); when present, initially deep-seated, or initially superficial. Nodes variously unilacunar, or tri-lacunar; exhibiting on either side a trace which divides, contributing the outermost lateral traces to each of the opposite leaves (e.g., in Coussarea and Faramea), or without split-lateral traces. Primary vascular tissues in a cylinder, without separate bundles; collateral. Internal phloem absent. Cortical bundles absent. Medullary bundles absent. Secondary thickening absent (Galieae), or developing from a conventional cambial ring (nearly always), or anomalous (recorded only in Basanacantha and Rhabdodendron). The anomalous secondary thickening when present, via concentric cambia. Primary medullary rays narrow.

The wood ring porous, or semi-ring porous to diffuse porous. The vessels small (typically), or medium; typically numerous, solitary, or radially paired, or in radial multiples, or in tangential arcs (rarely). The vessel end-walls exclusively simple (in mature wood), or scalariform (rarely, in primary vessels). The vessels with vestured pits, or without vestured pits; with spiral thickening, or without spiral thickening. The axial xylem with tracheids; without vasicentric tracheids; with fibre tracheids, or without fibre tracheids; with libriform fibres, or without libriform fibres; not uncommonly including septate fibres, or without septate fibres. The fibres without spiral thickening. The parenchyma apotracheal (in species with non-septate fibres), or paratracheal (or sometimes absent). The secondary phloem not stratified. ‘Included’ phloem present (Basanacantha), or absent. The wood not storied.

Reproductive type, pollination. Plants hermaphrodite (usually), or monoecious, or polygamomonoecious, or dioecious (e.g. Coprosma); often heterostylous. Pollination entomophilous; mechanism conspicuously specialized (via stylar modifications for passive pollen presentation), or unspecialized.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’, or solitary (less often); in cymes, or in panicles, or in verticils, or in heads (rarely, e.g. Morindeae, Gardenieae). The ultimate inflorescence units cymose. Inflorescences with involucral bracts (when capitate), or without involucral bracts; pseudanthial, or not pseudanthial. Flowers small, or medium-sized; regular; mostly 4 merous, or 5 merous; cyclic; tetracyclic. Free hypanthium absent.

Perianth with distinct calyx and corolla, or petaline (the calyx often absent or almost so); 7–15; 2 whorled, or 1 whorled; the two whorls isomerous. Calyx when detectable 4, or 5; 1 whorled; polysepalous (but epigynous), or gamosepalous (the lobes varying from practically lacking to enlarged and brightly coloured); when gamosepalous, entire, or lobulate, or blunt-lobed, or toothed; regular (mostly), or bilabiate (rarely), or unequal but not bilabiate (sometimes with one, or several, enlarged members); persistent, or not persistent; accrescent, or non-accrescent; open in bud (commonly), or contorted, or valvate. Epicalyx present (e.g. Fernelia, Flagenium), or absent. Corolla (3–)4, or 5, or 8–10; 1 whorled; gamopetalous; imbricate, or valvate, or contorted; tubular, or hypocrateriform; regular, or bilabiate (rarely).

Androecium 4, or 5. Androecial members adnate (to the corolla tube, or attached at its very base in Coprosma); free of one another (usually), or coherent (occasionally, via the anthers, e.g. Argostemma); 1 whorled. Androecium exclusively of fertile stamens. Stamens 4, or 5; inserted near the base of the corolla tube, or midway down the corolla tube, or in the throat of the corolla tube; isomerous with the perianth; oppositisepalous; alternating with the corolla members. Anthers cohering (occasionally), or connivent, or separate from one another; dehiscing via longitudinal slits (mostly), or dehiscing via pores (apically, e.g. Argostemma); introrse; tetrasporangiate; slightly appendaged (rarely?), or unappendaged. The anther appendages observed in Coprosma apical (by slight extension of the connective). Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or isobilateral, or decussate. Anther wall initially with one middle layer; of the ‘dicot’ type. Tapetum glandular. Pollen shed in aggregates (in the Gardenieae), or shed as single grains (mostly); when aggregated, in tetrads. Pollen grains aperturate, or nonaperturate (rarely); 3(–4) aperturate (mostly), or 4–12 aperturate; colpate (Paederieae, Galieae, Spermacoceae p.p.), or porate (Gardenieae), or colporate (polycolporate in Richardsonia), or foraminate; 2-celled (14 genera), or 3-celled (9 genera).

Gynoecium 2(–9) carpelled. Carpels usually reduced in number relative to the perianth. The pistil 1 celled (rarely), or 2(–9) celled. Gynoecium syncarpous; synovarious to eu-syncarpous; inferior (nearly always), or superior (only Gaertnera and Pagamea). Ovary 1 locular (rarely e.g. Gardenia), or 2(–9) locular. Gynoecium when bilocular (i.e. usually), transverse. Epigynous disk often present. Gynoecium stylate. Styles 1 (often simple), or 2(–5); free, or partially joined; attenuate from the ovary, or from a depression at the top of the ovary; apical; shorter than the ovary to much longer than the ovary. Stigmas wet type, or dry type; papillate, or non-papillate; Group II type and Group IV type. Placentation when unilocular, parietal; when two or more locular, axile. Ovules in the single cavity when unilocular, 6–100 (‘many’); 1–50 per locule (commonly one (Rubioideae), to ‘many’); pendulous, or horizontal, or ascending; anatropous, or hemianatropous; unitegmic; tenuinucellate. Endothelium not differentiated. Embryo-sac development Polygonum-type. Antipodal cells formed; 3; proliferating (occasionally), or not proliferating; ephemeral, or persistent. Endosperm formation nuclear. Embryogeny solanad.

Fruit fleshy, or non-fleshy; dehiscent, or indehiscent, or a schizocarp. Mericarps when schizocarpic 2(–9); comprising achenes, or comprising nutlets, or comprising drupelets (?). Fruit when non-schizocarpic a capsule, or a berry, or a drupe. Capsules septicidal, or loculicidal, or septicidal and loculicidal, or circumscissile (e.g. Mitratheca). Fruit 1–30 seeded. Seeds endospermic (usually), or non-endospermic (Guettardinae). Endosperm ruminate, or not ruminate; when present, oily. Seeds winged (rarely), or wingless. Cotyledons 2; flat (or rarely involute). Embryo achlorophyllous (8/11); straight (usually), or curved.

Seedling. Germination phanerocotylar, or cryptocotylar.

Physiology, phytochemistry. C3 and CAM. C3 physiology recorded directly in Borreria, Coprosma, Crucianella, Galium, Richardia. CAM recorded directly in Hydnophytum, Myrmecodia. Anatomy non-C4 type (Cephalanthus, Crucianella, Diodia, Galium). Sugars transported as sucrose (in three genera). Inulin recorded (Cinchona, Gibbs 1974). Cyanogenic, or not cyanogenic. Cynogenic constituents phenylalanine-derived (?). Alkaloids present (commonly), or absent. Anthraquinones detected (21 genera); derived from shikimic acid (mostly), or polyacetate derived (Asperula). Arbutin present. Iridoids detected; ‘Route I’ type (normal and seco), or ‘Route II’ type (b). Saponins/sapogenins present (occasionally), or absent. Proanthocyanidins present, or absent. Flavonols present (mostly), or absent; kaempferol and quercetin (mostly), or kaempferol, or quercetin. Ellagic acid absent (9 species, 9 gebera). Ursolic acid present. Aluminium accumulation demonstrated, or not found.

Geography, cytology. Frigid zone to tropical. Cosmopolitan. X = (6-)9/11(-17).

Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Gentianiflorae; Gentianales. Cronquist’s Subclass Asteridae; Rubiales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; lamiid; Order Gentianales.

Species 6000. Genera about 600; Acranthera, Acrobotrys, Acunaeanthus, Adinauclea, Agathisanthemum, Aidia, Aidiopsis, Airosperma, Aitchisonia, Alberta, Aleisanthia, Alibertia, Allaeophania, Alleizettella, Allenanthus, Alseis, Amaiouma, Amaracarpus, Amphiasma, Amphidasya, Ancylanthos, Anomanthodia, Antherostele, Anthorrhiza, Anthospermum, Antirhea, Aoranthe, Aphaenandra, Aphanocarpus, Appunettia, Appunia, Arctophyllum, Argocoffeopsis, Argostemma, Asemnantha, Asperula, Astiella, Atractocarpus, Atractogyne, Augusta, Aulacocalyx, Badusa, Balmea, Bataprine, Bathysa, Batopedina, Belonophora, Benkara, Benzonia, Berghesia, Bertiera, Bikkia, Blandibractea, Blepharidium, Bobea, Boholia, Borojoa, Bothriospora, Botryarrhena, Bouvardia, Brachytome, Bradea, Brenania, Breonadia, Burchellia, Burttdavya, Byrsophyllum, Caelospermum, Calanda, Callipeltis, Calochone, Calycophyllum, Calycosia, Calycosiphonia, Canephora, Canthium, Capirona, Captaincookia, Carpacoce, Carphalea, Carterella, Casasia, Catesbaea, Catunaregam, Cephaelis, Cephalodendron, Ceratopyxis, Ceriscoides, Ceuthocarpus, Chaetostachydium, Chalepophyllum, Chamaepentas, Chapelieria, Chassalia, Chazaliella, Chimarrhis, Chiococca, Chione, Chlorochorion, Chomelia, Choulettia, Chytropsia, Cigarilla, Cinchona, Cladoceras, Clarkella, Coccochondra, Coccocypselum, Coddia, Coelopyrena, Coffea, Coleactina, Colletoecima, Commitheca, Condaminea, Conostomium, Coprosma, Coptophyllum, Coptosapelta, Corynanthe, Coryphothamnus, Cosmibuena, Cosmocalyx, Coursiana, Coussarea, Coutaportla, Coutarea, Cowiea, Craterispermum, Cremaspora, Cremocarpon, Crobylanthe, Crocyllis, Crossopteryx, Crucianella, Cruciata, Cruckshanksia, Crusea, Cuatrecasasiodendron, Cubanola, Cuviera, Cyclophyllum, Damnacanthus, Danais, Deccania, Declieuxia, Dendrosipanea, Dentella, Deppea, Diacrodon, Dialypetalum, Dibrachyonostylus, Dichilanthe, Dictyandra, Didymaea, Didymochlamys, Didymopogon, Didymosalpynx, Diodella, Diodia, Dioecrescis, Dioicodendron, Diplospora, Discospermum, Diyaminauclea, Dolichodelphys, Dolicholobium, Dolichometra, Dolicera, Duidania, Dunnia, Duperrea, Duroia, Durringtonia, Ecpoma, Eizia, Elaeagia, Eleutheranthus, Emmenopterys, Emmeorhiza, Eosanthe, Eriosemopsis, Erithalis, Ernodea, Etericius, Euclinia, Exallage, Exostema, Fadogia, Fadogiella, Fagerlindia, Faramea, Ferdinandusa, Feretia, Fergusonia, Fernelia, Flagenium, Flexanthera, Gaertnera, Gaillonia, Galiniera, Galium, Gallienia, Galopina, Gamotopea, Gardenia, Gardeniopsis, Genipa, Gentingia, Geophila, Gillespiea, Gleasonia, Glionnetia, Glossostipula, Gomphocalyx, Gonzalagunia, Gouldia, Greenea, Greeniopsis, Guettarda, Gynochtodes, Gyrostipula, Habroneuron, Haldina, Hallea, Hamelia, Hyataella, Hedstromia, Hedyotis, Hedythyrsus, Heinsenia, Heinsia, Hekistocarpa, Heterophyllaea, Hillia, Himalrandia, Hindsia, Hintonia, Hippotis, Hitoa, Hodgkinsonia, Hoffmannia, Holstianthus, Homollea, Homolliella, Houstonia, Hutchinsonia, Hydnophytum, Hydrophylax, Hymenocnemis, Hymenocoleus, Hymenodictyon, Hyperacanthus, Hypobathrum, Hyptianthera, Ibetralia, Indopolysolenia, Isertia, Isidorea, Ixora, Jackiopsis, Janotia, Jaubertia, Joosia, Jovetia, Kailarsenia, Kajewskiella, Keenania, Keetlia, Kelloggia, Kerianthera, Khasiaclunea, Klossia, Knoxia, Kochummenia, Kohautia, Kraussia, Kutchubaea, Ladenbergia, Lagynias, Lamprothamnus, Lasianthus, Lathraeocarpa, Lecananthus, Lecanosperma, Lecariocalyx, Lelya, Lemyrea, Lepidostoma, Leptactina, Leptodermis, Leptomischus, Leptoscela, Leptostigma, Lerchea, Leucocodon, Leucolophus, Limnosipanea, Lindenia, Litosanthes, Lucinaea, Luculia, Lucya, Ludekia, Macbrideina, Machaonia, Macrocnemum, Macrosphyra, Maguireocharis, Maguireothamnus, Malanea, Manettia, Manostachya, Mantalania, Margaritopsis, Maschalocorymbus, Maschalodesme, Massularia, Mastixiodendron, Mazaea, Melanopsidium, Mericarpaea, Merumea, Metadina, Meyna, Micrasepalum, Microphysa, Mitchella, Mitracarpus, Mitrasacmopsis, Mitriostigma, Molopanthera, Monosalpinx, Montamans, Morelia, Morierina, Morinda, Morindopsis, Motleyia, Mouretia, Multidentia, Mussaenda, Mussaendopsis, Mycetia, Myonima, Myrmecodia, Mymeconauclea, Myrmephytum, Naletonia, Nargedia, Neanotis, Neblinathamnus, Nematostylis, Nenax, Neobertiera, Neoblakea, Neobreonia, Neofranciella, Neohymenopogon, Neolamarckia, Neolaugeria, Neopentanisia, Nernstia, Nertera, Nesohedyotis, Neurocalyx, Nichallea, Nodocarpaea, Nonatelia, Normandia, Nostolachma, Ochreinauclea, Octotropis, Oldenlandia, Oldenlandiopsis, Oligocodon, Omiltemia, Opercularia, Ophiorrhiza, Ophriococcus, Oregandra, Oreopolus, Osa, Otiophora, Otocalyx, Otomeria, Ottoschmidtia, Oxyanthus, Pachystigma, Pachystylus, Paederia, Pagamea, Pagameopsis, Palicourea, Pamplethantha, Paracephaelis, Parachimarrhis, Paracorynanthe, Paragenipa, Paraknoxia, Parapentas, Paratriaina, Pauridiantha, Pausinystalia, Pavetta, Payera, Pelagodendron, Pentagonia, Pentaloncha, Pentanisia, Pentanopsis, Pentas, Pentodon, Peponidium, Perakanthus, Perama, Peratanthe, Peripeplus, Pertusadina, Petagomoa, Petitiocodon, Phellocalyx, Phialanthus, Phitopis, Phuopsis, Phyllacanthus, Phyllis, Phyllocrater, Phyllomelia, Phyllohydrax, Picardaea, Pimentelia, Pinariphyllon, Pinckneya, Pittoniotis, Placocarpa, Placopoda, Plectronia, Plectoniella, Pleiocarpidia, Pleiocoryne, Pleiocraterium, Plocama, Poecilocalyx, Pogonolobus, Pogonopus, Polysphaeria, Polyura, Pomax, Porterandia, Portlandia, Posoqueria, Pouchetia, Praravinia, Pravinaria, Preussiodora, Prismatomeris, Proscephaleium, Psathura, Pseudaidia, Pseudogaillonia, Pseudogardenia, Pseudohamelia, Pseudomantalania, Pseudomussaenda, Pseudonesohedyotis, Pseudopyxis, Pseudosabicea, Psilanthus, Psychotria, Psydrax, Psyllocarpus, Pteridocalyx, Pterogaillonia, Pubistylus, Putoria, Pygmaeothamnus, Pyragra, Pyrostria, Rachicallis, Ramosmania, Randia, Raritebe, Readea, Remijia, Rennellia, Retiniphyllum, Rhadinopus, Raphidura, Rhipidantha, Rhopalobrachium, Rhyssocarpus, Richardia, Riqueuria, Robynsia, Roigella, Ronabea, Rondeletia, Rothmannia, Rubia, Rudgea, Rustia, Rutidea, Rytigynia, Sabicea, Sacosperma, Saldinia, Salzmannia, Saprosma, Sarcopygme, Schachtia, Schismatoclada, Schizenterospermum, Schizocalyx, Schizocolea, Schizomussaenda, Schizostigma, Schmidtottia, Schradera, Schumanniophyton, Schwendenera, Scolosanthus, Scyphiphora, Scyphochlamys, Scyphostachys, Sericanthe, Serissa, Shaferocharis, Sherardia, Sherbournia, Siderobombyx, Siemensia, Simira, Sinoadina, Sipanea, Sipaneopsis, Siphonandrium, Sommera, Spathichlamys, Spermacoce, Spermadictyon, Sphinctanthus, Spiradiclis, Squamellaria, Stachyarrhena, Stachyococcus, Staelia, Standleya, Steenisia, Stelechantha, Stephanococcus, Stevensia, Steyermarkia, Stichianthus, Stilpnophyllum, Stipularia, Stomandra, Streblosa, Streblosiopsis, Strempelia, Striolaria, Strumpfia, Stylosiphonia, Suberanthus, Sukunia, Sulitia, Synaptantha, Syringantha, Tamilnadia, Tammsia, Tapiphyllum, Terenna, Tarennoidea, Temnocalyx, Temnopteryx, Tennantia, Thecorchus, Thogsennia, Thyridocalyx, Timonius, Tobagoa, Tocoyena, Tortuella, Trailliaedoxa, Tresanthera, Triainolepis, Tricalysia, Trichostachys, Trigonopyren, Trukia, Tsiangia, Uragoga, Urophyllum, Valantia, Vangueria, Vangueriella, Vangueriopsis, Versteegia, Villaria, Virectaria, Warburgina, Warszewiczia, Wendlandia, Wernhamia, Wiasemskya, Wittmackanthus, Xanthophytum, Xantonnea, Xerococcus, Yutajea, Zuccarinia.

General remarks. For an assessment of the subfamilial classification, see Bremer’s (1996) analyses of morphological and molecular data.

Economic uses, etc. Sources of coffee (Coffea), quinine (Cinchona, ipecac (Cephaelis), and many ornamentals (e.g. Gardenia, Rubia, Mitchella, Coprosma).

Illustrations. • Technical details: Coffea, Galium, Rubia. • Technical details: Bouvardia, Cinchona, Coprosma, Leptodermis, Luculia. • Technical details: Coffea (Lindley). • Technical details: Pavetta (Thonner). • Temperate herbs: Asperula, Galium, Rubia, Sherardia (B. Ent. compilation). • Woody forms: Bouvardia, Rondeletia, Lindenia, Ixora (Chittenden). • Sub-shrubs: Hindsia (Chittenden). • Manettia (climber), Myrmecodia (myrmecophilous epiphyte), Hillia (Chittenden). • Asperula pusilla and A. scoparia: Hooker, Fl. Tasmaniae (1860). • Bouvardia triphylla var. splendens: Bot. Reg. xxvi, 37 (1840). • Coprosma foetidissima: Hooker, Fl. Antarctica (1844). • Coprosma nitida: Hooker, Fl. Tasmaniae (1860). • Galium ciliare: Hooker, Fl. Tasmaniae (1860). • Gardenia pannea Lindl.: Bot. Reg. 1952, 1837. • Guettarda speciosa: Bot. Reg. 1393, 1831. • Hamiltonia scabra: Bot. Reg. 1235, 1829. • Hindsia violacea: Bot. Reg. 1844, 40. • Manettia glabra: as M. cordifolia, Bot. Reg. 1866 (1836). • Nertera dichondraefolia and Leptostigma setulosa (as Nertera): Hooker, Fl. Novae-Zelandiae (1853). • Opercularia ovata: Hooker, Fl. Tasmaniae (1860). • Pentas lanceolata: as P. carnea, Bot. Reg. 1844, 32. • Phuopsis stylosa: as Crucianella, Bot. Reg. XXIV, 55 (1838). • Posoqueria versicolor: Bot. Reg. 26, 1841. • Rondeletia odorata: Bot. Reg. 1905 (1836). • Rondeletia longiflora: Bot. Reg. 29 (42), 1843.

The descriptions are offered for casual browsing only. We strongly advise against extracting comparative information from them. 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 or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG).

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 16th May 2016.’.