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The families of flowering plants

L. Watson and M.J. Dallwitz

Bignoniaceae Juss.

Including Crescentiaceae Dum.

Habit and leaf form. Trees, or shrubs, or lianas, or herbs (rarely). Self supporting, or climbing; when climbing stem twiners, or tendril climbers (via modified terminal leaflets), or root climbers; the twiners twining anticlockwise (Tecoma). Leaves opposite (mostly), or whorled, or alternate (rarely, then spiral); petiolate; non-sheathing; compound (usually), or simple; pinnate, or palmate, or bipinnate, or multiply compound. Lamina when simple dissected, or entire; when dissected pinnatifid, or palmatifid. Leaves exstipulate; leaf development not ‘graminaceous’. Domatia occurring in the family (known from 14 genera); manifested as pits (rarely), or pockets, or hair tufts.

Leaf anatomy. The leaf lamina dorsiventral (usually), or bifacial (isobilateral recorded in Kigelia). Stomata present; nearly always mainly confined to one surface (abaxial); anomocytic, or paracytic, or diacytic (Kigelia). Adaxial hypodermis present (rarely, e.g. in Pandorea), or absent. The mesophyll with sclerenchymatous idioblasts (spicular cells), or without sclerenchymatous idioblasts; containing crystals. The crystals mostly solitary-prismatic (in the form of small octahedra, prisms or needles: large solitary crystals and druses rare). Minor leaf veins without phloem transfer cells (Catalpa, Jacaranda, Tecomella).

Axial (stem, wood) anatomy. Cork cambium present; initially deep-seated, or initially superficial. Nodes unilacunar (3 to several traces). Primary vascular tissues in a cylinder, without separate bundles. Internal phloem absent. Cortical bundles absent. Medullary bundles present (these inversely orientated, e.g. in Campsis, Tecoma), or absent. Secondary thickening developing from a conventional cambial ring, or anomalous (represented by assorted variations, featured in Solereder’s generic key). The anomalous secondary thickening via concentric cambia (e.g. Campsis, Clytostoma, Tecomaria, where a second series of bundles forms internally to the primary cylinder, in the pith; or in the secondary cortex), or from a single cambial ring. Primary medullary rays wide (in lianes), or mixed wide and narrow.

The wood variously ring porous, or semi-ring porous, or diffuse porous. The vessels small, or medium (mostly), or large. The vessel end-walls simple (typically), or reticulately perforated and simple. The vessels without vestured pits; with spiral thickening, or without spiral thickening. The axial xylem without fibre tracheids; with libriform fibres; including septate fibres (commonly, especially in climbers), or without septate fibres. The fibres without spiral thickening. The parenchyma paratracheal. The secondary phloem stratified into hard (fibrous) and soft (parenchymatous) zones (commonly), or not stratified. ‘Included’ phloem present (as wedges in the xylem), or absent. The wood storied, or partially storied (VP, VPI), or not storied.

Reproductive type, pollination. Plants hermaphrodite. Pollination entomophilous, or ornithophilous, or cheiropterophilous.

Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; when aggregated, in cymes, or in racemes. The ultimate inflorescence units cymose, or racemose. Inflorescences terminal, or axillary; usually dichasial, tending to cincinnial. Flowers somewhat irregular to very irregular. The floral irregularity involving the perianth and involving the androecium (K irregular, C sometimes more or less regular). Flowers more or less 5 merous; cyclic; tetracyclic. Hypogynous disk usually present.

Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; gamosepalous; entire, or toothed; campanulate; unequal but not bilabiate, or bilabiate; often open in bud. Corolla 5; 1 whorled; gamopetalous. Corolla lobes markedly shorter than the tube, or about the same length as the tube. Corolla imbricate, or valvate (rarely); usually campanulate, or funnel-shaped; bilabiate (often, the upper lip with two lobes, the lower with three), or regular (rarely).

Androecium (4–)5. Androecial members adnate (to the corolla tube); markedly unequal; free of one another; 1 whorled. Androecium nearly always including staminodes, or exclusively of fertile stamens (occasionally all five members are fertile, or the usual posterior staminode is absent). Staminodes 1 (the posterior, adaxial member), or 3; in the same series as the fertile stamens; representing the posterior median member, or the posterior median member and the posterior-lateral pair. Fertile stamens representing the anterior-lateral pair (mostly), or the posterior-lateral pair and the anterior-lateral pair. Stamens (2–)4(–5); inserted near the base of the corolla tube, or midway down the corolla tube; didynamous (mostly), or not didynamous, not tetradynamous; reduced in number relative to the adjacent perianth (usually), or isomerous with the perianth; oppositisepalous; alternating with the corolla members. Anthers connivent (usually), or separate from one another; dehiscing via longitudinal slits; bisporangiate, or tetrasporangiate. Endothecium developing fibrous thickenings, or not developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral. Tapetum amoeboid. Pollen grains aperturate (usually), or nonaperturate; 2–12 aperturate; colpate, or colporate; 2-celled (in 13 genera).

Gynoecium 2 carpelled. The pistil 1 celled, or 2 celled, or 4 celled. Gynoecium syncarpous; synovarious to synstylovarious; superior. Ovary 1 locular, or 2 locular, or 4 locular. Locules secondarily divided by ‘false septa’, or without ‘false septa’. Gynoecium median; stylate. Styles 1; attenuate from the ovary; apical. Stigmas 1; 2 lobed; wet type; papillate; Group III type. Placentation when unilocular parietal; when 2 or 4 locular axile. Ovules in the single cavity when unilocular, 6–100 (to ‘many’); 6–50 per locule (‘many’); ascending; orthotropous, or hemianatropous; unitegmic; tenuinucellate. Endothelium differentiated. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral to persistent. Synergids hooked (large). Hypostase usually present (but weak). Endosperm formation cellular. Endosperm haustoria present; chalazal, or chalazal and micropylar.

Fruit non-fleshy (usually), or fleshy (rarely); dehiscent (usually), or indehiscent (rarely); a capsule (usually), or a berry (rarely). Capsules septicidal, or loculicidal. Seeds non-endospermic (with Schlegelieae excluded); winged (usually), or wingless. Cotyledons 2; flat (enlarged, foliaceous). Embryo achlorophyllous (4/4); straight.

Seedling. Germination phanerocotylar, or cryptocotylar.

Physiology, phytochemistry. C3. C3 physiology recorded directly in Catalpa, Chilopsis. Sugars transported as oligosaccharides + sucrose (predominantly), or as sugar alcohols + oligosaccharides + sucrose. Not cyanogenic. Alkaloids present, or absent. Anthraquinones detected (4 genera); derived from shikimic acid. Verbascosides detected (8 genera). Cornoside detected (Eccremocarpus). Arbutin absent. Iridoids detected (very commonly); ‘Route I’ type (normal, doubtfully), or ‘Route II’ type (normal and decarb.). Saponins/sapogenins present (rarely), or absent. Proanthocyanidins absent. Flavonols present, or absent; when present, quercetin. Ellagic acid absent (8 species, 7 genera). Ursolic acid present. Aluminium accumulation not found.

Geography, cytology. Temperate (a few), sub-tropical and tropical (mainly). Widespread, with Catalpa common to the Old and New Worlds. N = 20 (mostly). Supposed basic chromosome number of family: 7.

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 650. Genera 110; Adenocalymna, Amphilophium, Amphitecna, Anemopaegma, Argylia, Arrabidaea, Astianthus, Barnettia, Bignonia, Callichlamys, Campsidium, Campsis, Catalpa, Catophractes, Ceratophytum, Chilopsis, Clytostoma, Colea, Crescentia, Cuspidaria, Cybistax, Delostoma, Deplanchea, Digomphia, Dinklageodoxa, Distictella, Distictis, Dolichandra, Dolichandrone, Eccremocarpus, Ekmanianthe, Fernandoa, Fridericia, Gardnerodoxa, Glaziova, Godmania, Haplolophium, Haplophragma, Heterophragma, Hieris, Incarvillea, Jacaranda, Kigelia, Lamiodendron, Leucocalantha, Lundia, Macfadyena, Macranthisiphon, Manaosella, Mansoa, Markhamia, Martinella, Melloa, Memora, Millingtonia, Mussatia, Neojobertia, Neosepicaea, Newbouldia, Nyctcalos, Ophiocolea, Oroxylum, Pajanelia, Pandorea, Parabiognonia, Paragonia, Paratecoma, Parmentiera, Pauldopia, Perianthomega, Periarrabidaea, Perichlaena, Phryganocydia, Phyllarthron, Phylloctenium, Piriadacus, Pithecoctenium, Pleionotoma, Podranea, Potamoganos, Pseudocatalpa, Pyrostegia, Radermachera, Rhigozum, Rhodocolea, Roentgenia, Romeroa, Saritaea, Sparattosperma, Spathicalyx, Spathodea, Sphingiphila, Spirotecoma, Stereospermum, Stizophyllum, Tabebuia, Tanaecium, Tecoma, Tecomanthe, Tecomella, Tourrettia, Tynanthus, Urbanolophium, Xylophragma, Zeyheria.

General remarks. For discussion of classificatory problems posed by Scrophulariaceae, impinging on Bignoniaceae, Buddlejaceae, Callitrichaceae, Plantaginaceae, Hippuridaceae, Lentibulariaceae, and Hydrostachydaceae, and such problem genera as Paulownia and Schlegelia, see Olmstead and Reeves (1995), who provided preliminary insights from chloroplast gene sequencing. Intkey analyses of our compiled descripions show Bignoniaceae differing from Scrophulariaceae sensu stricto in tendencies among assorted overlapping characters, but absolutely only in the open calyx lobes, the non-endospemic seeds, and the amoeboid tapetum.

Economic uses, etc. Important timber from Tabebuia (West Indian boxwood), Catalpa.

Illustrations. • Kigelia africana, as K. aethiopica: Thonner. • Le Maout and Decaisne: Catalpa, Tecoma. • Le Maout and Decaisne: Amphitecna latifolia, as Crescentia obovata: Lindley. • Amphicome arguta: Bot. Reg. XXIV, 19 (1838). • Fridericia crassa, as Arrabidaea: Hook. Ic. Pl. 30 (1911). • Bignonia capreolata var. atrosanguinea: Bot. Mag. 106 (1880). • Bignonia unguis-cati: as B. tweediana, Bot. Reg. xxvi, 45 (1840). • Bignonia unguis-cati: as B. picta, Bot. Reg. 45, 1842. • Colea floribunda: Bot. Reg. 19, 1841. • Delostoma dentatum: Bot. Mag. 95 (1869). • Eccremocarpus scaber: Bot. Reg. 939, 1825. • Pandorea jasminoides: as Tecoma, Bot. Reg. 2002, 1837. • Perichlaena richardii: Hook. Ic. Pl. 28 (1902). • Radermachera pentandra: Hook. Ic. Pl. 28 (1902). • Tecomaria capensis: Bot. Reg. 1117, 1827. • Tecoma nyassae: Hook. Ic. Pl. 14 (1880–82). • Zeyheria montana: Martius, Nova Gen. et Spec. Pl. Brasiliensium 2 (1826). • Leaf hairs (Solereder, 1908).

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.’.