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The families of flowering plants

L. Watson and M.J. Dallwitz

Leguminosae-Caesalpinioideae Kunth

Alternatively Caesalpiniaceae R.Br.; ~ Leguminosae.

Including Ceratoniaceae Link, Detariaceae (DC.) Hess

Habit and leaf form. Trees, or shrubs, or herbs, or lianas; resinous, or not resinous. ‘Normal’ plants (mostly), or switch-plants; the switch forms with the principal photosynthesizing function transferred to stems, or phyllodineous. Leaves well developed (usually), or much reduced. The herbs perennial; without conspicuous aggregations of leaves. Self supporting (mostly), or climbing; the climbers stem twiners, or tendril climbers (via stem or leaf tendrils), or scrambling. Mesophytic, or xerophytic. Heterophyllous (rarely), or not heterophyllous. Leaves evergreen, or deciduous; minute to very large; alternate; spiral, or distichous; ‘herbaceous’, or leathery, or membranous, or modified into spines; petiolate to subsessile (usually), or sessile; non-sheathing; gland-dotted, or not gland-dotted; compound (commonly), or simple (or ostensibly so); pulvinate (usually), or epulvinate; when compound, unifoliolate, or ternate, or pinnate (commonly, either pari- or imparipinnate), or bipinnate (commonly), or bifoliolate (or - notab ly in many Bauhinieae - the single organ deeply bilobed to apically retuse). Leaflets pulvinate, or epulvinate. Lamina when simple dissected (i.e., commonly bilobed in Bauhinieae), or entire. Leaves stipulate (nearly always?), or exstipulate (?). Stipules intrapetiolar; scaly, or leafy, or spiny; caducous, or persistent. Leaf development not ‘graminaceous’. Domatia never explicitly mentioned for the family.

Leaf anatomy. The leaf lamina dorsiventral. Leaves with ‘pearl glands’ (sometimes), or without ‘pearl glands’. Mucilaginous epidermis present, or absent (?). Stomata paracytic, or anomocytic, cyclocytic, and actinocytic. Hairs of numerous kinds present (in the subfamily). Lamina with secretory cavities, or without secretory cavities. Secretory cavities containing oil, or containing mucilage, or containing resin (?). The mesophyll containing mucilage cells, or not containing mucilage cells (?); with sclerenchymatous idioblasts, or without sclerenchymatous idioblasts. Minor leaf veins with phloem transfer cells, or without phloem transfer cells (for taxonomic details, see Watson and Gunning 1981).

Axial (stem, wood) anatomy. Secretory cavities present, or absent. Cork cambium present; initially deep-seated, or initially superficial (?). Nodes tri-lacunar, or penta-lacunar (?). Primary vascular tissues in a cylinder, without separate bundles, or comprising a ring of bundles (?). Internal phloem absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring, or anomalous. The anomalous secondary thickening when present, via concentric cambia (e.g. Koompassia).

The vessel end-walls simple. The vessels with vestured pits, or without vestured pits (?). The axial xylem at least sometimes including septate fibres, or without septate fibres (?). The parenchyma apotracheal, or paratracheal (?). The secondary phloem stratified into hard (fibrous) and soft (parenchymatous) zones, or not stratified (?). ‘Included’ phloem present, or absent (?). The wood storied, or partially storied (VPI).

Reproductive type, pollination. Plants hermaphrodite, or monoecious, or andromonoecious, or polygamomonoecious. Pollination mechanism conspicuously specialized, or unspecialized.

Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; when aggregated, in racemes, or in corymbs, or in fascicles, or in panicles. The ultimate inflorescence units racemose. Inflorescences terminal, or axillary. Flowers minute to large; somewhat irregular to very irregular (mostly), or regular (not infrequently); commonly more or less zygomorphic; resupinate (?), or not resupinate. The floral irregularity involving the perianth and involving the androecium. Flowers ‘pseudo-papilionaceous’, or neither papilionaceous nor pseudo-papilionaceous (the corolla absent in over 20 genera, and when present nearly always ‘ascending’, ambiguously papilionaceous only in Eligmocarpus); pentamerous or not; tricyclic, or tetracyclic (usually), or pentacyclic to polycyclic. Floral receptacle developing a gynophore (often), or with neither androphore nor gynophore. Free hypanthium present (e.g. in most Detarieae), or absent.

Perianth with distinct calyx and corolla (usually), or sepaline (at least sometimes, in nearly 30 genera), or vestigial to absent (in Icuria only); (3–)5, or (6–)10(–11); (1–)2 whorled; isomerous, or anisomerous. Calyx 5, or (3–)5(–6); 1 whorled; polysepalous, or partially gamosepalous, or gamosepalous (mostly); unequal but not bilabiate, or bilabiate, or regular; imbricate, or valvate; with the median member anterior. Corolla when present, (1–)5; 1 whorled; polypetalous, or gamopetalous (in Sympetalandra only); usually imbricate (and usually ascending); usually unequal but not bilabiate (commonly with some members small or reduced to vestiges), or regular (or almost so, in over 40 genera); green, or white, or yellow, or orange, or red, or pink, or purple. Petals clawed, or sessile.

Androecium (1–)10, or 10–50 (often ten, but commonly fewer, ‘many’ in Maniltoa). Androecial members unbranched; free of the perianth; all equal, or markedly unequal; free of one another (sometimes), or coherent (in a variety of configurations); when cohering 1 adelphous, or 2 adelphous; 1 whorled. Androecium exclusively of fertile stamens, or including staminodes. Stamens (1–)3–10(–50); reduced in number relative to the adjacent perianth, or isomerous with the perianth, or diplostemonous to polystemonous. Anthers separate from one another, or connivent; dorsifixed, or basifixed; versatile, or non-versatile; dehiscing via pores (some Cassieae), or dehiscing via longitudinal slits; latrorse to introrse; tetrasporangiate. Endothecium developing fibrous thickenings. Microsporogenesis simultaneous. Anther wall initially with one middle layer, or initially with more than one middle layer (?); of the ‘dicot’ type. Tapetum usually glandular. Pollen shed in aggregates (very rarely — Afzelia, Diptychandra), or shed as single grains; when aggregated, in tetrads. Pollen grains aperturate; (2–)3(–4) aperturate, or 6 aperturate (?); colporate (commonly), or porate, or colpate, or rugate (?); 2-celled (11 genera).

Gynoecium 1 carpelled. Carpels reduced in number relative to the perianth. The pistil 1 celled. Gynoecium monomerous; of one carpel; superior. Carpel apically stigmatic; 1–100 ovuled (i.e. to ‘many’, usually in alternating rows along the placenta). Placentation marginal (along the ventral suture). Gynoecium median (the placenta posterior, on the ventral suture). Ovary sessile to stipitate. Ovules pendulous to ascending (?); biseriate; arillate, or non-arillate; anatropous, or campylotropous to amphitropous, or hemianatropous (?); bitegmic; crassinucellate. Outer integument contributing to the micropyle, or not contributing to the micropyle. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral, or persistent (mostly). Synergids hooked. Endosperm formation nuclear. Endosperm haustoria present; chalazal, or lateral (rarely). Embryogeny onagrad, or asterad, or caryophyllad (?).

Fruit non-fleshy, or fleshy. The fruiting carpel dehiscent, or indehiscent; a legume (usually), or a follicle, or an achene, or samaroid, or a loment, or drupaceous. Fruit elastically dehiscent, or passively dehiscent (?). Dispersal unit the seed, or the fruit. Seeds endospermic (sometimes copiously so), or non-endospermic; small to large (?). Seeds with starch, or without starch (?). Seeds with amyloid, or without amyloid. Cotyledons 2; flat. Embryo chlorophyllous; straight (mostly), or curved (radicle usually straight, rarely somewhat oblique). Micropyle zigzag, or not zigzag (?).

Seedling. Germination phanerocotylar, or cryptocotylar. Nitrogen-fixing root nodules present (seemingly rarely, by contrast with the other subfamilies), or absent.

Physiology, phytochemistry. C3. C3 physiology recorded directly in Acacia, Cassia, Cercidium, Gleditsea, Hoffmanseggia. Anatomy non-C4 type (Acacia, Cassia, Mimosa, etc. — all and 150 genera examined by L.W., see Watson and Dallwitz 1983). Sugars transported as sucrose (in all 15 genera sampled). Cyanogenic, or not cyanogenic (?). Cynogenic constituents tyrosine-derived, or phenylalanine-derived, or of Hegnauer’s ‘Group C’, or leucine-derived (?). Alkaloids present (commonly), or absent (?). Arbutin present, or absent. Iridoids not detected. Proanthocyanidins present, or absent (?); when present, cyanidin, or delphinidin, or cyanidin and delphinidin (?). Flavonols present (mostly), or absent (?); kaempferol and quercetin, or quercetin and myricetin, or kaempferol, quercetin, and myricetin (?). Ellagic acid consistently absent. Aluminium accumulation not found. Sieve-tube plastids P-type; type IV (subtype (b) in 18 genera).

Geography, cytology. Paleotropical, Neotropical, Cape, and Australian. Temperate, sub-tropical, and tropical. Mostly tropical and subtropical.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Fabiflorae; Fabales. Cronquist’s Subclass Rosidae; Fabales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; fabid; Order Fabales.

Species about 400 (?). Genera about 166; Acrocarpus, Adenolobus, Afzelia, Amherstia, Androcalymma, Anthonotha, Apaloxylon, Aphanocalyx, Aprevalia, Apuleia, Arapatiella, Arcoa, Augouardia, Baikiaea, Barklya, Batesia, Bathiaea, Baudouinia, Bauhinia, Berlinia, Brachycylix, Brachystegia, Bracteolanthus, Brandzeia, Brenierea, Brodriguesia, Brownea, Browneopsis, Burkea, Bussea, Caesalpinia, Campsiandra, Candolleodendron, Cassia, Cenostigma, Ceratonia, Cercidium, Cercis, Chidlowia, Colophospermum, Colvillea, Conzattia, Copaifera, Cordeauxia, Crudia, Cryptosepalum, Cynometra, Daniella, Dansera, Delonix, Detarium, Dialium, Dicorynia, Dicymbe, Didelotia, Dimorphandra, Diptychandra, Distemonanthus, Duparquetia, Eligmocarpus, Elizabetha, Endertia, Englerodendron, Eperua, Erythrophleum, Eurypetalum, Gigasiphon, Gilbertiodendron, Gilletiodendron, Gleditsia, Goniorrachis, Gossweilerodendron, Griffonia, Guibourtia, Gymnocladus, Haematoxylum, Hardwickia, Heterostemon, Hoffmannseggia, Holocalyx, Humboldtia, Hylodendron, Hymenaea, Hymenostegia, Intsia, Isoberlinia, Jacqueshuberia, Julbernardia, Kalappia, Kaoue, Kingiodendron, Koompassia, Labichea, Lasiobema, Lebruniodendron, Lemuropisum, Leonardoxa, Leucostegane, Librevillea, Loesenera, Lophocarpinia, Lysidice, Lysiphyllum, Macrolobium, Maniltoa, Martiodendron, Melanoxylon, Mendoravia, Mezoneuron, Michelsonia, Microberlinia, Moldenhauera, Monopetalanthus, Mora, Neochevalierodendron, Oddoniodendron, Orphanodendron, Oxystigma, Pachyelasma, Paloue, Paloveopsis, Paramacrolobium, Parkinsonia, Pellegriniodendron, Peltogyne, Peltophorum, Petalostylis, Phanera, Phyllocarpus, Piliostigma, Plagiosiphon, Poeppigia, Polystemonanthus, Prioria, Pseudomacrolobium, Pterogyne, Pterolobium, Recordoxylon, Saraca, Schizolobium, Schizoscyphus, Schotia, Sclerolobium, Scorodophloeus, Sindora, Sindoropsis, Stachyothyrsus, Stahlia, Stemonocoleus, Stenodrepanum, Storckiella, Stuhlmannia, Sympetalandra, Tachigalia, Talbotiella, Tamarindus, Tessmannia, Tetraberlinia, Tetrapterocarpon, Thylacanthus, Trachylobium, Uittienia (not Vittienia, see P. van Rijckevorsel in Taxacom, March 2009), Umtiza, Vouacapoua, Wagatea, Zenia, Zenkerella, Zuccagnia.

General remarks. This temporary description reflects incomplete breakdown of esoteric characters across the subfamilies of Leguminosae sensu lato (q.v.). However, it is clear that the many features which tend to distinguish the subfamilies all involve rather numerous exceptions, are very incompletely documented, or are not universally applicable.

Illustrations. • Technical details: Cercis, Cassia, Copaifera. • Technical details: Bauhinia. • Bauhinia corymbosa: Bot. Reg. 1839, 47. • Bauhinia racemosa: Hook. Ic. Pl. 2 (1837). • Brownea grandiceps: Bot. Reg. 30, 1841. • Cassia biflora: Bot. Reg. 1310, 1830. • Cassia floribunda var. herbertiana (as Cassia herbertiana): Bot. Reg. 1422, 1831. • Cassia occidentalis: Bot. Reg. 83, 1815. • Cathartocarpus bacillus, probably = Senna bacillaris: Bot. Reg. 881, 1825. • Senna odorata (as Cassia australis), Bot. Reg. 1322, 1830. • Sindora wallichii: Hook. Ic. Pl. 11 (1867–71). • Leaf hairs of Caesalpinioideae (Bauhinia, Cassia and Humboldtia: Solereder, 1908). • Sections of winged and undulating Bauhinia stems, with split xylem masses (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: 13th March 2017.’.