| # The genera of Leguminosae-Caesalpinioideae and Swartzieae |

L. Watson and M.J. Dallwitz

### Chamaecrista Moench

~ Cassia subgenera Lasiorhegma (Vog.) Benth. and Absus Symon.

Sooja Sieb., Grimaldia Schrank.

Type species: C. nictitans (L.) Moench.

Habit and leaf form. Trees, or shrubs, or herbs (often herbaceous with woody base, sometimes monocarpic); unarmed.

Phyllotaxy distichous, or spiral. The leaves compound (usually), or ostensibly simple (e.g., C. basifolia); of C. basifolia, palmately veined; pinnate (usually, often with nectariferous petiolar glands); usually paripinnate. The leaflets many per leaf to few per leaf; opposite or sub-opposite; petiolulate, or sessile to sub-sessile; without noticeably twisted petiolules; symmetrical or nearly so; pinnately veined, with a predominant ‘midrib’, or palmately nerved. Stipules present, persistent and conspicuous in mature leaves, or absent or early caducous or very inconspicuous in mature leaves (?); if present, leafy, or membranous; not connate. Stipels absent.

Inflorescence and floral morphology. The flowers aggregated into inflorescences, or solitary. The inflorescences axillary, or terminal; unbranched, or branched; simple racemes (usually), or simple corymbs (?). The flowers not distichous. Bracts absent at anthesis, or persistent beyond anthesis (?). Bracteoles present (at or near the base of the pedicel); absent at anthesis, or persistent beyond anthesis (?); free.

The flowers hermaphrodite; not ‘papilionaceous’; pentamerous, or not pentamerous throughout; departing from pentamery often in the androecium; coloured. Floral tube length relative to total hypanthium + calyx length when applicable, about 0.25. Hypanthium absent, the androecium hypogynous. Calyx 5; covering the rest of the flower in bud; gamosepalous, or polysepalous (?); more or less regular, or markedly irregular; members imbricate. Corolla present; slightly irregular to very irregular (often very heteromorphic, the two abaxial petals variously oblique); spreading, 5; including greatly reduced members to without greatly reduced members; polypetalous. Petals clawed, or clawed and sessile; imbricate; imbricate-ascending, or imbricate-descending with the posterior petal (vexillum) outside (the vexillum usually interior in bud, but sometimes exterior on one or both sides); yellow, or yellow and red (being sometimes marked red near the claw). Disk absent. The androecium comprising 2–10 members; without the three long-filamented, short-anthered abaxial stamens characteristic of Cassia; members all free of one another; members all more or less equal in length, or markedly unequal (then the two cycles differing in length, but without the accrescence towards the abaxial side of the flower characteristic of Cassia sensu stricto); typically including staminodia, or comprising only fertile stamens (the thecae ciliate along the sutures). Fertile stamens (2–)5–10. Anthers attached at the base of the connective; dehiscing via pores or short slits. Ovary sessile or subsessile, or stipitate; free. Stigma dilated, or not dilated. Ovules few to numerous.

Fruit, seed and seedling. Fruit a two-valved pod (plano-compressed, elastically dehiscent); straight, or curved; internally septate; valves twisting and enrolling during dehiscence; winged longitudinally (rarely, narrowly along the sutures), or not noticeably winged; becoming woody, or not becoming woody (the valves variously papery, leathery or more or less woody). The mature valves usually without prominent venation, or with conspicuous, prominent, raised venation (?); conspicuous venation if prominently veined, predominantly longitudinal, or not predominantly longitudinal. Seeds compressed laterally, endospermic; not arillate (the funicle dilated deltoidly); with a straight or slightly oblique radicle; amyloid-negative; with galactomannan. Cotyledons of Type 1, or Type 2, or Type 3 (?); with a vascular system in one plane; epigeal.

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

Leaf lamina epidermes. Epidermal crystals not seen either adaxially or abaxially. Simple unbranched hairs common; scabrid, or smooth. No compound or branched eglandular hairs seen. Capitate glands not seen. Hooked hairs present, or not seen. Cassieae-type leaf pseudo-glands not seen. Expanded and embedded hair-feet absent. Basally bent hairs present. Adaxial: Adaxial interveinal epidermal cell walls straight in optical section; conspicuously pitted; of medium thickness. Stomata adaxially very rare. Abaxial: Abaxial stomata predominantly paracytic. Abaxial epidermis papillate interveinally, or not papillate (?); if papillate, with the papillae not over-arching the stomata. Abaxial interveinal epidermal cell walls straight, or gently undulating; not conspicuously pitted in optical section; scarcely staining with safranin; thin.

Wood anatomy. Wood with septate fibres, or without septate fibres; not storied; without normal intercellular canals; without traumatic canals. Intervascular pits medium to large.

Pollen ultrastructure. Tectum punctate, or reticulate (?); smooth punctate, or puncticulate, or rugulose punctate (?); rugulose reticulate. Length of colpi greater than one half pole to pole distance, or less than one half pole to pole distance (rarely?).

Cytology. Basic chromosome number, x = 14. 2n = 14 and 26.

Species number and distribution. About 250 species. Primarily neotropical, especially in E. Brazil, but also in the cool temperate Americas, tropical and temperate southern Africa, tropical and cool temperate Asia, Malesia and tropical Australia.

Tribe. Cassieae.

Comments. Widely cultivated.

Miscellaneous. Illustrations: • Chamaecrista mimosoides: Engler & Drude, Pflanzenwelt Afrikas 9 (1915). • C. apoucouita: Fl. Brasiliensis 15 (1870). • C. calcioides and Senna uniflora: Fl. Brasiliensis 15 (1870). • C. basifolia: Fl. Brasiliensis 15 (1870). • C. chamaecristoides and C. tragacanthoides: Fl. Brasiliensis 15 (1870). • C. kirkii (as Cassia): Sreyaert, in Fl. du Congo Belge (1952). • C. mimosoides (as Cassia): Sreyaert, in Fl. du Congo Belge (1952). • Chamaecrista diphylla: Schery, Ann. Miss. Bot. Gard. 38 (1951). • C. nictitans var. jaliscensis (as C. stenocarpa): Schery, Ann. Miss. Bot. Gard. 38 (1951). • Chamaecrista glandulosa var. glandulosa, e.m. scanned pollen (Graham & Barker, 1981).

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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