The genera of Leguminosae-Caesalpinioideae & Swartzieae
Type species: M. excelsa Benth.
Habit and leaf form. Huge trees; without specialized short shoots; unarmed.
Phyllotaxy spiral. The leaves compound; pinnate; paripinnate (3–4 jugate). The leaflets glabrous, few per leaf; opposite or sub-opposite; without noticeably twisted petiolules. Stipules absent or early caducous or very inconspicuous in mature leaves. Stipels absent.
Inflorescence and floral morphology. The inflorescences terminal; branched; of racemose units; panicles (of dense spikes). The flowers not distichous. Bracts small, scale-like, caducous, absent at anthesis. Bracteoles absent; absent at anthesis.
The flowers small; hermaphrodite; pentamerous. Floral tube length relative to total hypanthium + calyx length when detectable, less than 0.5. Hypanthium present (but usually slight), or absent, the androecium hypogynous. The perianth comprising distinct calyx and corolla. Calyx 5; not covering the rest of the flower in bud; gamosepalous; urceolate-campanulate, shortly 5-toothed, more or less regular; members imbricate. Corolla present; regular to slightly irregular (the petals obovate-oblong, subequal); much exceeding the calyx, 5; without greatly reduced members; polypetalous. Petals ?all shortly clawed. Disk absent. The androecium comprising 10 members; declinate; members markedly unequal; including staminodia. The staminodia 5; longer than the stamens and alternating with the petals. Fertile stamens alternating with the staminodes, alternisepalous 5. Anthers attached at the base of the connective (but sagittate below, and covered with long deciduous white hairs). Ovary shortly stipitate (with the glabrous style about equalling the stamens); free. Stigma very small, not dilated (or scarcely so). Ovules few to numerous (4–9?).
Fruit, seed and seedling. Fruit dehiscent, 1–6 seeded; straight; elliptic or oblong, becoming woody. Seeds non-endospermic; with a straight or slightly oblique radicle.
Transverse section of lamina. Leaves without conspicuous phloem transfer cells in the minor veins. Druses absent from the mesophyll. Mesophyll secretory cavities absent. Adaxial hypodermis present. 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 not seen. No compound or branched eglandular hairs seen. Capitate glands not seen. Expanded and embedded hair-feet absent. Adaxial: Adaxial interveinal epidermal cell walls markedly sinuous in high-focus optical section; not conspicuously pitted; of medium thickness. Stomata adaxially very rare. Abaxial: Abaxial stomata predominantly paracytic. Abaxial epidermis not papillate. Abaxial interveinal epidermal cell walls markedly sinuous in high-focus optical section; not conspicuously pitted in optical section; staining normally with safranin; medium-thick.
Wood anatomy. Wood without septate fibres; not storied; without normal intercellular canals; without traumatic canals. Intervascular pits very small.
Pollen ultrastructure. Tectum punctate; rugulose punctate. Length of colpi greater than one half pole to pole distance (without a margocolpus).
Species number and distribution. 7 species. Tropical South America, West Indies.
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: 22nd March 2017. delta-intkey.com/caes’.