Caesalpinia L. Sp. Pl. 1: 380 1753, descr. emended E. Gagnon & G. P. Lewis

Gagnon, Edeline, Bruneau, Anne, Hughes, Colin E., de Queiroz, Luciano Paganucci & Lewis, Gwilym P., 2016, A new generic system for the pantropical Caesalpinia group (Leguminosae), PhytoKeys 71, pp. 1-160 : 27-29

5. Caesalpinia L. Sp. Pl. 1: 380 1753, descr. emended E. Gagnon & G. P. Lewis Figs 10 , 11A-F

Poinciana L., in part (1753).

Brasilettia (DC.) Kuntze (1891), non sensu Britton & Rose (1930).

Diagnosis.

Caesalpinia resembles Guilandina , but differs in habit, comprising armed shrubs and small trees (vs. armed lianas and scrambling/trailing shrubs). It also differs in having racemes of bisexual flowers (vs. racemes of unisexual flowers), sepals imbricate in bud, with a pronounced lower cucullate sepal (vs. sepals valvate in bud), zygomorphic corollas variable in colour (yellow, white, red, orange, pink or green), with petals extending well beyond the sepals (vs. zygomorphic to sub-actinomorphic, yellow corollas, with petals barely extending beyond the sepals), coriaceous, oblong-elliptic to linear, laterally compressed, glabrous pods (vs. oblong-elliptic inflated pods, usually armed with 5-10 mm long spinescent bristles), and obovoid, laterally compressed seeds (vs. obovoid globular seeds).

Type.

Caesalpinia brasiliensis L.

Emended description.

Shrubs or small trees, usually 1-6 m tall, armed with curved deflexed prickles (except Caesalpinia nipensis which is unarmed), these either in pairs at the base of leaves, or scattered along the shoots (or both), or sometimes on woody protuberances at the base of trunks and stems; young shoots terete, glabrous and eglandular. Stipules not seen. Leaves alternate, bipinnate, c. 4-30 cm long, ending with a pair of pinnae, unarmed, or sometimes with a pair of prickles at the insertion of the pinnae on the leaf rachis, sometimes also at the insertions of the leaflets on the pinna rachis; pinnae opposite, in (1-) 2-6 pairs per leaf; leaflets alternate to opposite, in 3-13 pairs per pinna, short-petiolulate, blades suborbicular, obovate or elliptic, apex mucronate, rounded or emarginate, base cuneiform, rounded or oblique; main vein centric, secondary veins reticulate. Inflorescence a terminal or axillary raceme or panicle of pedicellate, bisexual flowers, c. 5-37 cm long, unarmed; bracts lanceolate or ovate, apex acute to acuminate, caducous. Flowers zygomorphic, c. 13-25 mm long; calyx comprising a hypanthium with 5 sepals, that are each c. 7-17 mm long, glabrous to occasionally finely puberulous, always eglandular, the lower sepal strongly cucullate and covering the other 4 sepals in bud, all sepals caducous, but hypanthium persistent as a free ring around the pedicel as the fruit matures; petals 5, variable in colour (yellow, white, red, orange, or green; certain horticultural varieties are also pink), the corolla also variable in shape (related to different pollination systems: bees, butterflies, birds and bats); stamens 10, free, c. 10-65 mm long, the filaments pubescent, eglandular; ovary glabrous and eglandular. Fruit a wingless, unarmed, coriaceous, glabrous, eglandular, oblong-elliptic, or linear pod, with a marcescent style forming an acute apex, c. 34-120 × 7-26 mm, explosively dehiscent, with twisting valves, 3-7-seeded. Seeds laterally compressed, obovate, up to 10 mm in diameter.

Geographic distribution.

Caesalpinia , as re-circumscribed here, is reduced to around nine species (a detailed taxonomic revision is needed to properly delimit species), and is now restricted to the Neotropics (apart from the pantropically cultivated Caesalpinia pulcherrima ). All the Old World species previously included in Caesalpinia s.s. sensu Lewis (2005) are here transferred to other genera. One species ( Caesalpinia cassioides ) occurs in the northern Andes from Peru to Colombia, one ( Caesalpinia pulcherrima ) is likely native in Guatemala and the state of Sonora in Mexico), two occur in the Caribbean (one, Caesalpinia nipensis , is endemic to Cuba, the other widely distributed and possibly divisible into six separate species, all of which are listed below). Caesalpinia pulcherrima is a widely cultivated ornamental throughout the tropics. It includes red, orange, pink, and pure yellow-flowered forms and cultivated specimens are usually unarmed and lack bristles (unlike wild specimens which are armed and bristly).

Habitat.

Seasonally dry tropical forests, coastal thicket, bushland and thorn scrub, dry plains and riparian woodland, on soils derived from limestone or sandstone.

Etymology.

Named by Linnaeus for Andrea Cesalpino (1519-1603), Italian naturalist, botanical collector, systematist and philosopher, physician to Pope Clement VIII, professor of medicine and botany in Pisa and Rome.

References.

Britton and Rose (1930); Macbride (1943: 191, 194-195); Ulibarri (1996); Barreto Valdés (2013).

Figures

Figure 10. Caesalpinia cassioides Willd. A median leaflet B, C median leaflets (to show variation) D inflorescence E, F stem armature G flower H calyx opened out I calyx margin J median petal K upper lateral petal, L stamen M gynoecium N stigma O leaf and immature fruits P single immature fruit. A, D, E, Q from Mayolo 325 B, C, R from Silverstone-Sopkin 2004 F from Sandeman 4613 G-P from Silverstone-Sopkin 5139. Drawn by Sue Wickison.

Figure 11. Caesalpinia bahamensis Lam. A inflorescence D fruits (G. P. Lewis, Cuba, Lewis 1853 (K )). Caesalpinia nipensis Urb. B flowers E fruits (G. P. Lewis, Cuba, Lewis 1838 (K )). Caesalpinia cassioides Willd. C inflorescence (C. E. Hughes, Ancash, Peru, Hughes et al. 2228 (K )). Caesalpinia pulcherrima L. (Sw.) F inflorescence (C. E. Hughes, Sonora, Mexico, unvouchered); Denisophytum pauciflorum (Griseb.) E. Gagnon & G. P. Lewis G flower and leaves (G. P. Lewis, Cuba, Lewis 1854 (K )) H branch with spine-tipped woody protuberances (B. Torke, Cuba, Torke et al. 1424 (NY )). Denisophytum madagascariense R. Vig. I flowers and fruits (G. P. Lewis, Madagascar, Lewis et al. 2158 (K )). Gelrebia trothae (Harms) E. Gagnon & G. P. Lewis J inflorescence (P. J. Cribb, Tanzania, unvouchered).