Dinizia Ducke, Arch. Jard. Bot. Rio de Janeiro 3: 76. 1922.

Figs 95, 97

Type.

Dinizia excelsa Ducke

Description.

Large forest canopy-emergent unarmed trees (Fig. 95F) (some individuals over 60 m), sometimes with buttresses, bark breaking off in large woody plates. Stipules subulate, caducous ( D. excelsa) or unknown ( D. jueirana-facao). Leaves bipinnate, eglandular, the pinnae alternate to subopposite, leaflets alternate. Inflorescence a compound spiciform raceme (Fig. 95G). Flowers actinomorphic, hermaphrodite or functionally staminate, shortly pedicellate; hypanthium short; calyx valvate in bud, with 5 short, broadly triangular lobes; petals 5, free, imbricate; stamens 10, essentially free, anthers eglandular, dorsifixed; pollen in monads or in gemmate permanent tetrads; a nectarial ring at the hypanthium base; ovary short-stipitate, style apically dilated with a large terminal, tubular to funnel-shaped stigma. Fruit coriaceous or woody, indehiscent and marginally compressed or dehiscent along both sutures (Fig. 95E, H). Seeds hard, laterally compressed, lacking a pleurogram.

Chromosome number.

2 n = 26 (28) ( D. excelsa) (Santos et al. 2012).

Included species and geographic distribution.

Two species, one widespread in northern and central-western Amazonian Brazil, Guyana, and Suriname ( D. excelsa), the other narrowly restricted to a small area of Eastern Brazil in Espirito Santo state ( D. jueirana-facao) (Fig. 97).

Ecology.

Non-flooded Amazonian forests ( D. excelsa), or semi-deciduous Atlantic rainforest ( D. jueirana-facao).

Etymology.

Named by Ducke for his friend José Picanço Diniz, doctor-in-law and philanthropist.

Human uses.

The wood of D. excelsa is very resistant and has been widely used in civil and naval construction, for railway sleepers, cabinetwork and joinery, as well as for battens, props, beams, girders, posts, stakes, door and window frames, floor-boards, carts, wagons and bridges (Lewis et al. 2017 and other references therein).

Notes.

The genus was placed in its own Dinizia group of tribe Mimoseae by Lewis and Elias (1981). Luckow et al. (2003), based on morphological and molecular data, found the genus to be more closely related to non-mimosoid caesalpinioid genera than to any genus in the Mimosoideae . Bruneau et al. (2008) and LPWG (2017) resolved Dinizia as occurring firmly outside the Mimoseae clade, close to some genera of the Dimorphandra group of Polhill and Vidal (1981), a placement that is supported by the study of Ringelberg et al. (2022) who resolved the genus as sister to Campsiandra . In addition to the striking difference in nodulation (nodulating in D. jueirana-facao vs not in D. excelsa), the two species also differ importantly in pollen (monads vs tetrads) and in ecology (Atlantic rainforest vs non-flooded Amazonian forests).

Taxonomic references.

Ducke (1922); Lewis et al. (2017).