The genera of Leguminosae-Caesalpinioideae & Swartzieae
Type species: M. brazzavillensis A. Chev.
Habit and leaf form. Trees; unarmed.
Phyllotaxy distichous. The leaves compound; pinnate; paripinnate. The leaflets small, emarginate, many per leaf; opposite or sub-opposite; sessile to sub-sessile; small, oblong, markedly asymmetrical (unequal-sided at the base); pinnately veined, with the laterals looped along the margins; without a continuous marginal nerve. Stipules absent or early caducous or very inconspicuous in mature leaves (caducous); intrapetiolar, large, oblong-linear, free, basally connate. Stipels absent.
Inflorescence and floral morphology. The inflorescences axillary; branched; of racemose units (?); panicles. The flowers not distichous. Bracts very large, imbricate and covering the inflorescence in the bud, but caducous and absent at anthesis. Bracteoles present; obovate, relatively large and enclosing the flower buds; persistent beyond anthesis; valvate.
The flowers hermaphrodite; zygomorphic, not pentamerous throughout; departing from pentamery in the calyx. Hypanthium present; tubular. The perianth comprising distinct calyx and corolla. Calyx 4; covering the rest of the flower in bud; not Swartzieae type; polysepalous; markedly irregular; members imbricate. Corolla present; slightly irregular (the petals subequal, with the posterior one larger than the rest and clawed); 5; without greatly reduced members; polypetalous. Petals clawed and sessile. The androecium comprising 10 members; with united members (the 9 abaxials basally united into a sheath which is split above, the adaxial one free); members all more or less equal in length; comprising only fertile stamens (the anthers uniform). Fertile stamens 10. Ovary stipitate (with a slender, truncate style); eccentric, with the stipe adnate. Ovules few (3–6).
Fruit, seed and seedling. Fruit a two-valved pod; curved (oblong, subfalcate, compressed); becoming woody. The mature valves with conspicuous, prominent, raised venation; conspicuous venation predominantly longitudinal (the valves keeled). Seeds not arillate; with a straight or slightly oblique radicle.
Transverse section of lamina. Leaves with conspicuous phloem transfer cells in the minor veins. Druses common in the mesophyll. Mesophyll secretory cavities (gland-dots) common; without a lining of epithelium. Adaxial hypodermis absent. Leaf girders absent. 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 absent. Basally bent hairs absent. Adaxial: Adaxial interveinal epidermal cell walls straight in optical section, or 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 straight, or gently undulating, or markedly sinuous in high-focus optical section; conspicuously pitted in optical section; staining normally with safranin; of medium thickness.
Wood anatomy. Wood without septate fibres; storied; without normal intercellular canals; with traumatic canals. Intervascular pits medium to large.
Pollen ultrastructure. Tectum striate; pole to pole striate. Length of colpi greater than one half pole to pole distance.
Species number and distribution. 2 species (M. bisulcata and M. brazzavillensis). West equatorial Africa.
Tribe. Detarieae (Amherstieae of Cowan and Polhill 1981); Amherstieae clade of Bruneau et al. (2008).
Miscellaneous. Illustrations: • M. bisulcata and M. brazzavillensis: Aubréville, Flore du Gabon (1968). • M. bisulcata leaflet: abaxial epidermis.
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’.