The genera of Leguminosae-Caesalpinioideae & Swartzieae
Type species: G. balsamiferum (Vermoesen) Harms.
Habit and leaf form. Trees; unarmed.
Phyllotaxy spiral. The leaves compound; pinnate; imparipinnate, or paripinnate. The leaflets pellucid-punctulate, few per leaf; alternate; petiolulate; with markedly twisted petiolules; with a strong, continuous marginal nerve. Stipules membranous. Stipels absent.
Inflorescence and floral morphology. The inflorescences branched; panicles (of long spike-like racemes). The flowers not distichous. Bracts caducous, minute, absent at anthesis. Bracteoles present; small, not enclosing the flower buds (minute); absent at anthesis; not valvate; free.
The flowers small; hermaphrodite; not pentamerous throughout; departing from pentamery in the calyx, or in the corolla, or in the androecium, or in the calyx, in the corolla, and in the androecium (in various combinations). Floral tube length relative to total hypanthium + calyx length about 0.5. Hypanthium present (small); shortly saucer-shaped to cupular. The perianth exclusively sepaline. Calyx 4(–5); pellucid punctulate, covering the rest of the flower in bud; polysepalous; more or less regular; members imbricate. Corolla absent. Disk absent. The androecium comprising (8–)10 members; members all free of one another; comprising only fertile stamens. Fertile stamens (8–)10. Anthers attached well above the base of the connective; dehiscing laterally; dehiscing longitudinally. Ovary obliquely ovoid, villous,with a short style, stipitate; free. Ovules solitary (pendulous).
Fruit, seed and seedling. Fruit samaroid, a two-valved pod; winged proximally to the single seed (i.e., the seed distal); not becoming woody. The mature valves with conspicuous, prominent, raised venation; conspicuous venation predominantly longitudinal. Seeds with a straight or slightly oblique radicle; amyloid-negative. Cotyledons hypogeal.
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; epithelium-lined. 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. No compound or branched eglandular hairs seen. Capitate glands not seen. Expanded and embedded hair-feet absent. 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 not papillate. Abaxial interveinal epidermal cell walls markedly sinuous in high-focus optical section; not conspicuously pitted in optical section; staining normally with safranin; thin.
Wood anatomy. Wood without septate fibres; not storied; with normal intercellular canals, or without normal intercellular canals; without traumatic canals. Intervascular pits medium to large.
Species number and distribution. 2 species (G. balsamiferum and G. joveri). Africa.
Tribe. Detarieae; Prioria clade of Bruneau et al. (2008).
Miscellaneous. Illustrations: • G. balsamiferum: Leonard, in Fl. du Congo Belge (1952). • G. balsamiferum and G. joveri: Aubréville, Flore du Gabon (1968). • G. balsamiferum, flower and fruit (Cowan & Polhill, 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: 22nd March 2017. delta-intkey.com/caes’.