The genera of Leguminosae-Caesalpinioideae & Swartzieae
Type species: M. excelsum Harms.
Habit and leaf form. High, large-crowned trees; unarmed.
Phyllotaxy distichous. The leaves compound; pinnate; imparipinnate. The leaflets pellucid-punctate many per leaf; opposite or sub-opposite, or alternate; without noticeably twisted petiolules; symmetrical or nearly so; pinnately veined, with a predominant midrib. Stipels absent.
Inflorescence and floral morphology. The inflorescences arising from branchlets beneath the young leaves; unbranched and branched; when branched, of racemose units; simple racemes, or panicles. The flowers not distichous. Bracts lanceolate. Bracteoles present; subulate, small, not enclosing the flower buds; persistent beyond anthesis.
The flowers hermaphrodite; not pentamerous throughout; departing from pentamery in the calyx, in the corolla, and in the androecium. Floral tube length relative to total hypanthium + calyx length about 0.25. Hypanthium more or less absent, the androecium hypogynous. The perianth exclusively sepaline. Calyx 2, or 3; covering the rest of the flower in bud; Swartzieae type (closed before flowering, splitting more or less irregularly into valvate lobes or teeth); gamosepalous (subglobose or depressed-globose in bud, splitting into 2 or three broad, deltoid, spreading or reflexed lobes); more or less regular to markedly irregular; members not imbricate. Corolla absent. Disk present and conspicuous (large and fleshy). The androecium comprising 12–18 members; not declinate; with united members (all very shortly connate at the base); members all more or less equal in length (the anthers small, ovoid); supposedly comprising only fertile stamens (see comment). Fertile stamens 12–18. Anthers attached well above the base of the connective; dehiscing longitudinally. Ovary long stipitate; free. Stigma not dilated (the shortish style curved-subulate). Ovules numerous (7–8).
Fruit, seed and seedling. Fruit indehiscent; ovoid, 4–5 seeded, fleshy within, not becoming woody. Seeds not arillate; amyloid-negative; with starch.
Transverse section of lamina. Leaves without conspicuous phloem transfer cells in the minor veins. Druses absent from the mesophyll. Mesophyll secretory cavities (gland-dots) common; without a lining of epithelium. 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 common; scabrid. No compound or branched eglandular hairs seen. Capitate glands not seen. Hooked hairs not seen. Cassieae-type leaf pseudo-glands not seen. Expanded and embedded hair-feet present; all medium to thick-walled; hair feet all simple, without vertical walls. Adaxial: Adaxial interveinal epidermal cell walls straight in optical section; conspicuously pitted, or not conspicuously pitted; thick. Stomata adaxially very rare. Abaxial: Abaxial stomata not predominantly paracytic (cyclocytic). Abaxial epidermis not papillate. Abaxial interveinal epidermal cell walls straight, or gently undulating; conspicuously pitted in optical section, or not conspicuously pitted in optical section; staining normally with safranin; thick.
Wood anatomy. Wood storied.
Pollen ultrastructure. Tectum punctate; rugulose punctate. Length of colpi greater than one half pole to pole distance.
Species number and distribution. 1 species (M. excelsum). Tropical Africa.
Tribe. Papilionoideae-Amburaneae (former Swartzieae).
Comments. Available descriptions imply absence of staminodes, so Brenan's depiction of the androecium is assumed here to show early-deciduous anthers.
Miscellaneous. Illustrations: • M. excelsum: Brenan, Fl. Tropical East Africa (1967).
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’.