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The families of flowering plants

L. Watson and M.J. Dallwitz

Gesneriaceae Dum.

Including Cyrtandracaceae N. Jack, Didymocarpeae (Didymocarpaceae) D. Don, Ramondiaceae (Ramondaceae) Godr. & Gren. ex Godr., Replicataceae Dulac

Habit and leaf form. Herbs (usually, sometimes slightly woody), or shrubs, or lianas (rarely). ‘Normal’ plants, or plants of very peculiar vegetative form (sometimes); sometimes remarkably neotenic (with spectacular reduction of the axis — e.g. Streptocarpus, where the plant has but one leaf which represents a cotyledon, the other cotyledon having atrophied early). Leaves well developed. Plants green and photosynthesizing. With a basal aggregation of leaves, or without conspicuous aggregations of leaves. Self supporting, or epiphytic (commonly), or climbing; climbers root climbers. Mesophytic. Heterophyllous (members of leaf pairs often very different in size), or not heterophyllous. Leaves opposite (usually), or alternate (rarely), or whorled (rarely); ‘herbaceous’, or leathery; petiolate; not gland-dotted; simple; epulvinate. Lamina entire (usually), or dissected; rarely pinnatifid; pinnately veined; cross-venulate. Leaves exstipulate. Lamina margins entire, or serrate, or dentate. Leaf development not ‘graminaceous’. Domatia occurring in the family (Mitraria); manifested as pits.

Leaf anatomy. The leaf lamina dorsiventral. Stomata anisocytic (often very large). Hairs present; eglandular and glandular (the former simple uniseriate, often containing red or blue sap, sometimes raised on pedestals; the latter with heads 2–6 or more celled, on stalks of varying lengths). Adaxial hypodermis present (commonly), or absent. Lamina with secretory cavities (accompanying the xylem, e.g., in Rhychoglossum and Monophyllaea), or without secretory cavities (usually). Secretory cavities when present, containing oil, or containing resin; schizogenous. The mesophyll with sclerenchymatous idioblasts, or without sclerenchymatous idioblasts; usually containing crystals. The crystals variable in frequency and form, druses and solitary-prismatic. Minor leaf veins without phloem transfer cells (Aeschynanthus, Isoloma, Mitraria).

Axial (stem, wood) anatomy. Secretory cavities present (in a few genera), or absent; when present, with oil, or with resin. Cork cambium present; initially deep-seated, or initially superficial. Nodes unilacunar, or tri-lacunar, or penta-lacunar; exhibiting on either side a trace which divides, contributing the outermost lateral traces to each of the opposite leaves (exemplified in species of Alloplectus, Cyrtandra, Didymocarpus, Drymonia, Didissandra and Hemiboea), or without split-lateral traces. Primary vascular tissues usually ultimately in a cylinder, without separate bundles (the bundles generally becoming united by interfascicular prosenchymatous elements); collateral. Internal phloem absent. Cortical bundles present (a single one, in the stem ridge of Rhynchoglossum obliquum), or absent. Medullary bundles present (e.g. Monophyllaea, Rhynchoglossum), or absent. Secondary thickening developing from a conventional cambial ring.

The vessels typically small (or very small), or medium (e.g., in Drymonia); solitary and in radial multiples (the latter often of 4 or more cells). The vessel end-walls simple. The vessels without vestured pits; without spiral thickening. The axial xylem with tracheids (“vascular tracheids often present”), or without tracheids; with fibre tracheids (Coronanthera), or without fibre tracheids (usually); with libriform fibres (isially), or without libriform fibres (Coronanthera); seemingly nearly always including septate fibres. The fibres without spiral thickening. The parenchyma paratracheal (or very sparse, or absent); wood partially storied (VPI, some Cyrtandra species), or not storied (?).

Reproductive type, pollination. Plants hermaphrodite, or monoecious (rarely). Pollination entomophilous, or ornithophilous, or cheiropterophilous.

Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’. The ultimate inflorescence units when flowers aggregated, cymose (usually), or racemose. Inflorescences terminal, or axillary, or epiphyllous. Flowers medium-sized to large; very irregular (usually), or somewhat irregular. The floral irregularity involving the perianth and involving the androecium, or involving the androecium. Flowers cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk often present (when ovary superior).

Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; gamosepalous (usually), or polysepalous (sometimes); usually valvate. Corolla 5; 1 whorled; gamopetalous; imbricate; rotate, or campanulate; bilabiate (usually), or unequal but not bilabiate, or regular (e.g. Ramonda).

Androecium 2–5. Androecial members adnate (to the corolla tube); markedly unequal (often), or all equal; free of one another (rarely), or coherent; 1 adelphous, or 2 adelphous; 1 whorled. Androecium exclusively of fertile stamens, or including staminodes. Staminodes 1–3 (replacing fertile members); in the same series as the fertile stamens; representing the posterior median member, or the posterior-lateral pair, or the posterior median member and the posterior-lateral pair (?). Fertile stamens representing the anterior-lateral pair, or the posterior-lateral pair and the anterior-lateral pair. Stamens 2, or 4(–5) (the posterior member occasionally present — e.g. Ramonda); inserted near the base of the corolla tube, or midway down the corolla tube, or in the throat of the corolla tube; commonly didynamous; reduced in number relative to the adjacent perianth (usually), or isomerous with the perianth; oppositisepalous. Anthers cohering, or connivent, or separate from one another (rarely); dehiscing via longitudinal slits. Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or decussate. Anther wall initially with one middle layer; of the ‘dicot’ type. Tapetum glandular. Pollen grains aperturate; (2–)3(–6) aperturate; colporate (usually, or colporoidate), or rugate; 2-celled (in 6 genera).

Gynoecium 2 carpelled. The pistil 1 celled, or 2 celled (rarely). Gynoecium syncarpous; synstylovarious to eu-syncarpous; superior to inferior. Ovary unilocular (mostly, by contrast with Scrophulariaceae), or plurilocular (e.g., Streptocarpus, Petrocosmea, Saintpaulia); 1 locular (usually), or 2 locular (through meeting of the two placentae). Gynoecium median. Epigynous disk when ovary inferior, commonly present. Styles 1; attenuate from the ovary; apical. Stigmas 1–2; 1–2 lobed; wet type, or dry type; papillate; Group II type, or Group III type. Placentation usually parietal; when bilocular, axile. Ovules in the single cavity usually (i.e. when unilocular), 15–100 (i.e. ‘many’); when bilocular 10–50 per locule (i.e. ‘many’); funicled, or sessile; non-arillate; anatropous; unitegmic; tenuinucellate. Endothelium differentiated (proximally only). Embryo-sac development Polygonum-type. Antipodal cells formed; 3; not proliferating; very ephemeral. Synergids slender, sometimes with long, tapering tips entering the micropyle and extending through its length. Endosperm formation cellular. Endosperm haustoria present; chalazal and micropylar. Embryogeny onagrad.

Fruit fleshy, or non-fleshy; dehiscent (usually), or indehiscent; a capsule (usually), or a berry (infrequently). Capsules loculicidal (usually), or valvular (sometimes), or septicidal (rarely). Seeds endospermic, or non-endospermic (Cyrtandroideae). Endosperm when present, oily. Seeds small. Cotyledons 2, or 1–2 (one being sometimes reduced or absent, and in some Streptocarpus species, the other enlarging to such an extent as to constitute virtually the whole plant, bearing flowers on its midrib). Embryo achlorophyllous (1/1); straight.

Seedling. Germination phanerocotylar.

Physiology, phytochemistry. C3 and CAM. C3 physiology recorded directly in Saintpaulia. CAM recorded directly in Codonanthe. Anatomy non-C4 type (Didymocarpus). Not cyanogenic. Alkaloids absent (one species). Anthraquinones detected (Streptocarpus); derived from shikimic acid. Verbascosides detected (many genera). Cornoside detected (several genera). Iridoids not detected. Saponins/sapogenins absent. Proanthocyanidins absent. Flavonols absent. Ellagic acid absent (4 species, 3 genera). Aluminium accumulation not found.

Special distinguishing feature. The funicles not as in Acanthaceae.

Geography, cytology. Temperate (a few), sub-tropical to tropical (mostly). Pantropical, a few temperate. X = 4–17(+). Supposed basic chromosome number of family: 8, or 9.

Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Lamiiflorae; Scrophulariales. Cronquist’s Subclass Asteridae; Scrophulariales. APG III core angiosperms; core eudicot; Superorder Asteranae; lamiid. APG IV Order Lamiales.

Species 2000. Genera about 140; Achanthonema, Achimines, Aeschynanthus, Agalmyla, Allocheilos, Alloplectus, Allostigma, Ancylostemon, Anetanthus, Anna, Anodiscus, Asteranthera, Beccarinda, Bellonia, Besleria, Boea, Boeicca, Bournea, Briggsia, Briggsiopsis, Bucinellina, Calcareoboea, Capanea, Cathayanthe, Championia, Chirita, Chiritopsis, Chrysothemis, Cobananthus, Codonanthe, Codonanthopsis, Colpogyne, Columnea, Conandron, Corallodiscus, Coronanthera, Corytoplectus, Cremosperma, Cubitanthus, Cyrtandra, Cyrtandromoea, Dayaoshania, Deinocheilos, Depanthus, Diastema, Didissandra, Didymocarpus, Didymostigma, Dolicholoma, Drymonia, Episcia, Epithema, Eucodonia, Fieldia, Gasteranthus, Gesneria, Gloxinia, Goyazia, Gyrocheilos, Gyrogyne, Haberlea, Hemiboea, Hemiboeopsis, Heppiella, Hexatheca, Hypocyrta, Isometrum, Jancaea, Koellikeria, Kohleria, Lagarosolen, Lembocarpus, Lenbrassia, Leptobaea, Lietzia, Linnaeopsis, Loxocarpus, Loxonia, Loxostigma, Lysionotus, Metabriggsia, Metapetrocosmea, Micraeschynanthus, Mitraria, Monophyllaea, Monopyle, Moussonia, Napeanthus, Nautilocalyx, Negria, Nematanthus, Neomortonia, Niphaea, Nodonema, Oerstedina, Opithandra, Orchadocarpa, Oreocharis, Ornithoboea, Oxychlamys, Paliavana, Paraboea, Paradrymonia, Parakohleria, Pearcea, Petrocodon, Petrocosmea, Pheidonocarpa, Phinaea, Phyllobaea, Platyadenia, Primulina, Pseudochirita, Ramonda, Reldia, Resia, Rhabdothamnopsis, Rhabdothamnus, Rhoogeton, Rhynchoglossum, Rhynchotechum, Rhytidophyllum, Rufodorsia, Saintpaulia, Sanango, Sarmienta, Schistolobos, Schizoboea, Sepikea, Sinningia, Smithiantha, Solenophora, Stauranthera, Streptocarpus, Tengia, Tetraphyllum, Thamnocharis, Titanotrichum, Trachystigma, Tremacron, Trisepalum, Tylopsacas, Vanhouttea, Whytockia.

Illustrations. • Le Maout and Decaisne: Ramonda. • Le Maout and Decaisne: Gesneria, Dircaea (= Corytholoma), Moussonia (= Isoloma), "Tidaea". • Le Maout and Decaisne: Ligeria (= Sinningia), Achimenes, Pentarhaphia. • Le Maout and Decaisne: Aeschynanthus, Columnea, Nematanthus, Streptocarpus. • Le Maout and Decaisne: Alloplectus, Tapeinotes (= Sinningia), Hypocyrta. • Streptocarpus cooperi: Thonner. • Columnea schiediana: Goebel. • Achimenes hirsuta: Bot. Reg. 29, 55 (1843). • Achimenes longiflora: Bot. Reg. 19, 1842. • Achimenes rosea: Bot. Reg. 65, 1841. • Aeschynanthus grandiflorus: Bot. Reg. 49, 1841. • Aeschynanthus ramosissimus: as A. maculatus, Bot. Reg. 28, 1841. • Besleria umbrosa: Martius, Nova Gen. et Spec. Pl. Brasiliensium 3 (1829). • Chirita sinensis: Bot. Reg. 1844, 59. • Drymonia serratula, as D. calcarata: Martius, Nova Gen. et Spec. Pl. Brasiliensium 3 (1829). • Drymonia serratula: as D. bicolor, Bot. Reg. XXIV, 4 (1838). • Episcia reptans: Martius, Nova Gen. et Spec. Pl. Brasiliensium 3 (1829). • Gesneria faucialis: as Gesnera, Bot. Reg. 1785, 1836. • Gesneria lateritia: as Gesnera, Bot. Reg. 1950, 1837. • Gesneria pumila subsp. neglecta, as Conradia: Hook. Ic. Pl. 9 (1852). • Isoloma longifolium: as Gesnera longifolia, Bot. Reg. 40, 1842. • Kohleria inaequalis, as Tydaea warscewiczii: Lemaire, Illustr. Horticole (1854). • Naegelia zebrina: Bot. Reg. 16, 1842. • Nematanthus hirsutus, as Hypocyrta: Martius, Nova Gen. et Spec. Pl. Brasiliensium 3 (1829). • Niphea oblonga: Bot. Reg. 5, 1842. • Rhabdothamnopsis sinensis: Hook. Ic. Pl. 28 (1905). • Sinningia tuberosa, as Gesneria: Martius, Nova Gen. et Spec. Pl. Brasiliensium 3 (1829). • Sinningia barbata and S. pusilla, as Tapina spp.: Martius, Nova Gen. et Spec. Pl. Brasiliensium 3 (1829). • Sinningia sceptrum, as Gesneria: Martius, Nova Gen. et Spec. Pl. Brasiliensium 3 (1829). • Streptocarpus caulescens: Bot. Mag. 111 (1885). • Titanotrichum oldhamii: Hook. Ic. Pl. 30 (1911).

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or 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). See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 5th March 2018.’.