The genera of Leguminosae-Caesalpinioideae and Swartzieae

L. Watson and M.J. Dallwitz

Bauhinia L. (sensu lato)

Including Adenolobus (Harvey ex Benth.) Torre & Hillcoat, Alvesia Welw., Amaria Mutis (B. petiolata and B. sessiliflora), Ariaria Cuervo, Barklya F. Muell., Binaria Raf. (B. glabra), Bracteolanthus de Witt, Cansenia Raf., Cardenasia Rusby, Casparia Kunth, Caspariopsis Britton and Rose, Caulotretus Rich. ex Schott (B. glabra), Elayuna Raf., Gigasiphon (Drake) Harms, Lacara Spreng., Lasiobema (Korth.) Miq., Locellaria Wellw., Lysiphyllum (Benth.) de Witt, Monoteles Raf. (? - unresolved), Pauletia Cav., Perlebia Spix and Mart., Phanera Lour., Piliostigma Hochst., Schnella Raddi (e.g., B. glabra, B. macrostachya), Telestria Raf., Tournaya Schmitz (= Gigasiphon), Tylosema (Schweinf.) Torre & Hillc. (= Phanera)

Type species: B. divaricata L.

Habit and leaf form. Trees (5), or shrubs (4), or climbers or scramblers (4: the Phanera group); with tendrils (4: the Phanera group), or without tendrils (5); armed (very rarely with intrastipular spines), or unarmed (usually: 8/8).

Phyllotaxy distichous (4/5), or spiral (3/5). The leaves compound (3), or ostensibly simple (4), or two-lobed (5); when simple or bilobed, palmately veined; when compound, bifoliolate (3/3); paripinnate (2/2). The leaflets few per leaf (two: 3/3); opposite or sub-opposite (1/1); sessile to sub-sessile (3/3); when bifoliolate, palmately nerved. Stipules absent or early caducous or very inconspicuous in mature leaves (8/8), or present, persistent and conspicuous in mature leaves (2/8); when present, leafy (1/8), or membranous (8/8, or in any combination); not connate (4/4). Stipels absent (3/3).

Inflorescence and floral morphology. The inflorescences sometimes cauliflorous, otherwise axillary (2/2), or terminal (2/2); unbranched, or branched; when branched, of racemose units (2/2); simple racemes (2/2), or simple corymbs (1/2), or panicles (2/2). The flowers not distichous (5/5). Bracts absent at anthesis (5/8), or persistent beyond anthesis (4/8). Bracteoles present (7/8), or absent (1: Barklya); small, not enclosing the flower buds (6/7), or relatively large and enclosing the flower buds (Bracteolanthus); absent at anthesis (7/8), or persistent beyond anthesis (6/8); not valvate (2/2).

The flowers all hermaphrodite (usually), or hermaphrodite and unisexual (sometimes polygamous, andromonoecious or dioecious in Bauhinia s. str., sometimes polygamo-dioecious or dioecious in Piliostigma); pentamerous (6), or not pentamerous throughout (7); departing from pentamery in the calyx (5/6), or in the corolla (1/6), or in the androecium (3/6); coloured (8/8). Floral tube length relative to total hypanthium + calyx length about 0.2–0.65–1. Hypanthium present (5/5: often greatly elongated, but sometimes nearly absent); cupular to tubular (rarely negligible). Calyx 1 (spathaceous), or 2–5 (with lobes or teeth, sometimes irregular); covering the rest of the flower in bud (5/8), or not covering the rest of the flower in bud (6/8); not Swartzieae type; gamosepalous (spathaceous, or dividing to mouth of hypanthium into 2–5 lobes; or irregularly lobed above), or polysepalous (sometimes in Lysiphyllum); more or less regular (7), or markedly irregular (7); members not imbricate (8/8). Corolla present; slightly irregular (7/8), or very irregular (Lasiobema, and sometimes in Phanera); 5; without greatly reduced members; polypetalous. Petals clawed (7), or sessile (5); imbricate; imbricate-ascending; white (6), or yellow (7), or red (5). Disk present and conspicuous (4/4), or absent (2/4). The androecium comprising 1–10 members; with united members (1), or members all free of one another; members all more or less equal in length (Barklya), or markedly unequal (8); including staminodia (6), or comprising only fertile stamens (4). Fertile stamens 1 (1), or 2 (2), or 3 (3), or 4 (2), or 5–9 (1), or 10 (7). Anthers nearly always attached well above the base of the connective (rarely sagittate); dehiscing via pores or short slits (1), or longitudinally. Ovary stipitate; free (6), or eccentric, with the stipe adnate (4). Stigma dilated (3), or not dilated (7). Ovules few (3), or numerous (8).

Fruit, seed and seedling. Fruit a two-valved pod (7), or indehiscent (2); straight (4/7), or curved (4/7); without markedly twisting or enrolling valves (5/5); becoming woody (3), or not becoming woody (8). The mature valves with conspicuous, prominent, raised venation (1/5: sometimes in Gigasiphon), or without prominent venation (5/5); conspicuous venation when present, oblique or reticulate, not predominantly longitudinal (2/2). Seeds endospermic (7), or non-endospermic (4); arillate (8: the hilum crescentic), or not arillate (1); with a straight or slightly oblique radicle (8), or with an inflexed radicle (Barklya only); amyloid-negative (1/1). Cotyledons flat (2/2); epigeal (2/2), or hypogeal (1/2).

Transverse section of lamina. Leaves without conspicuous phloem transfer cells in the minor veins (6/6). Druses common in the mesophyll (6/7), absent from the mesophyll (4/7). Mesophyll secretory cavities absent (7/7). Adaxial hypodermis present (Piliostigma), or absent (6/7). Leaf girders common (the veins transcurrent) (6/7), or absent (1/7). Laminae dorsiventral (7/7). Mesophyll without unaligned fibres or sclereids (7/7). Minor veins mainly with abundant accompanying fibres (7/7).

Leaf lamina epidermes. Epidermal crystals not seen either adaxially or abaxially (6/6). Simple unbranched hairs common (5/6), or not seen (Bracteolanthus); scabrid (sometimes, in Bauhinia s. str.), or smooth (5/5). No compound or branched eglandular hairs seen (6/6). Capitate glands not seen (6/6). Hooked hairs not seen (5/5). Cassieae-type leaf pseudo-glands not seen (5/5). Expanded and embedded hair-feet present (Piliostigma), or absent (5/6); all medium to thick-walled (1/1); hair feet all simple, without vertical walls (1/1). Basally bent hairs present (2/5), or absent (3/5). Adaxial: Adaxial interveinal epidermal cell walls straight in optical section (6/6), or markedly sinuous in high-focus optical section (sometimes, in Bauhinia s. str.); conspicuously pitted (3/5), or not conspicuously pitted (3/5); medium-thick (1/5), or of medium thickness (2/5), or medium-thin (1/5), or thin (1/5). Stomata adaxially common and widespread (sometimes, in Bauhinia s. str.), or adaxially very rare (6/6). Abaxial: Abaxial stomata predominantly paracytic (5/5). Abaxial epidermis not papillate (6/6). Abaxial interveinal epidermal cell walls straight, or gently undulating (6/6); conspicuously pitted in optical section (3/5), or not conspicuously pitted in optical section (3/5); scarcely staining with safranin (2/6), or staining normally with safranin (5/6); medium-thin (1/5), or thin (4/5).

Wood anatomy. Wood with septate fibres (1/2), or without septate fibres (1/2); storied (2/2), or not storied (1/2); without normal intercellular canals (2/2); without traumatic canals (2/2). Intervascular pits very small (1/1).

Pollen ultrastructure. Tectum punctate (Phanera), or reticulate (4/6), or striate (2/6); finely to moderately regularly reticulate (1/3), or rugulose reticulate (2/3), or verrucose reticulate (2/3); reticulate striate (1/2), or interwoven striate (1/2). Length of colpi greater than one half pole to pole distance (4/5), or less than one half pole to pole distance (2/5).

Cytology. Basic chromosome number, x = 13 (3/6), or 14 (4/6). 2n = 24 (3/5), or 26 (4/5), or 28 (3/5), or 42 (2/5), or 56 (1/5).

Species number and distribution. About 220 species (?). In warm regions.

Tribe. Cercideae.

Comments. Widely cultivated.

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, and classification. See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1993 onwards. The genera of Leguminosae-Caesalpinioideae and Swartzieae: descriptions, illustrations, identification, and information retrieval. In English and French. Version: 4th August 2019. delta-intkey.com’.

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