Gilbertiodendron sulfureum Burgt

IUCN Red List of Threatened Species https://www.iucnredlist.org/species/145397128/146092732

Conservation

LC - least concern

van der Burgt, X.M., Mackinder, B.A., Wieringa, J.J. et al. The Gilbertiodendron ogoouense species complex (Leguminosae: Caesalpinioideae), Central Africa. Kew Bulletin 70: 29. DOI https://doi.org/10.1007/s12225-015-9579-4

Type

Type: Gabon, Haute Ngounyé, entre Ndamba et Mimongo, 4 April 1926, G. M. P. C. Le Testu 5891 (holotype P! [P00754999], isotypes BM!, BR!, HBG!, NY!, WAG!).

Morphology General Habit

Tree, 5 – 23 m tall

Morphology Trunk

Trunk to 35 cm diam. Twigs puberulent, hairs to 0.2 mm long

Morphology Leaves Stipules

Stipules in pairs, free, reniform part persistent, flat, 10 – 22 × 7 – 18 mm, sparsely puberulent to glabrescent both sides; lanceolate part of stipule not seen

Morphology Leaves

Leaves paripinnate, to 26 × 16 cm; petiole 4 – 7 mm long, 2 – 3 mm diam., sparsely puberulent, hairs to 0.1 mm long; leaf rachis (3 –) 6 – 21 (– 24) cm long, puberulent, hairs to 0.1 mm long, stipels absent; petiolules 1 – 3 mm long, sparsely puberulent, hairs to 0.1 mm long

Morphology Leaves Leaflets

Leaflets papery, opposite, 4 – 9 (– 10) pairs, narrowly elliptic, 4 – 11 × 1.3 – 3.5 cm; smooth and somewhat glossy both sides, upper surface glabrous, lower surface same colour, sparsely puberulent to glabrescent, hairs appressed, to 0.1 mm long; midrib prominent both sides, glabrescent to glabrous above, sparsely puberulent below, hairs to 0.1 mm long; 10 – 12 pairs of secondary veins; leaflet base cuneate to obtuse, slightly oblique, apex acuminate and mucronate, acumen 0.5 – 2 cm long

Morphology General Glands

Glands 0 – 1 (– 2) per leaflet, at the distal margin 2 – 5 mm from the petiolule and occasionally at the proximal margin 10 mm from the apex

Morphology Reproductive morphology Inflorescences

Inflorescence a congested, axillary or terminal cluster of 1 to several panicles, densely puberulous, hairs to 0.4 mm long, internodes between fertile twig nodes becoming as short as 5 mm towards the apex of the twig, creating a dense cluster of panicles each 3 – 12 (– 19) cm long, panicle internodes 4 – 12 (– 20) mm long; lateral axes to 4 cm long, 10 – 12 flowers per cm

Morphology Reproductive morphology Flowers

Flowers slightly fragrant, floral bract inserted at base of pedicel, caducous, ovate, 2 × 1.5 mm, densely puberulous on both sides, hairs to 0.2 mm long, centre inside glabrous; pedicel 6 – 13 mm long, densely puberulous, dense light-coloured hairs to 0.1 mm long mixed with dense dark brown hairs to 0.4 mm long; bracteoles 2, elliptic, yellowish white, 5 – 6 (– 7) × 4 (– 5) mm, densely puberulous outside, dense light-coloured hairs to 0.1 mm long mixed at base with sparse dark brown hairs to 0.2 mm long, sparsely puberulous inside, centre inside glabrous; receptacle 1.5 mm high, 2 mm diam. at top, glabrous or with patches of hairs on adaxial and/or abaxial sides, hairs 0.3 mm long; sepals 5, narrowly triangular, 4 × 1 mm, apex acute, glabrous, sometimes a few hairs at the base outside; petals 5, alternate to sepals; adaxial petal white, glabrous, claw 3 mm long, blade bilobed, 4 – 5 mm high × 8 – 10 mm wide; the other 4 petals glabrous, narrowly triangular, 3 – 4 × 0.8 mm, apex acute; stamens 3, inserted alternate to the 4 small petals; filaments white, glabrous, 10 – 11 mm long; anthers glabrous, 2 mm long; 6 staminodes, filiform, to c. 0.5 mm long, inserted on a staminodal tube c. 0.5 mm long, tapering towards the top, encircling ¾ of the ovary stipe opposite the large petal; ovary light green, 2.5 × 1.5 × 0.5 mm, 4 – 5 ovules, margins densely hirsute, hairs to 0.8 mm long, sides glabrous; stipe 0.5 mm long; style white, 8 – 10 mm long, lower part hirsute, upper part glabrous, stigma capitate

Morphology Reproductive morphology Fruits

Fruits oblong-rectangular, brown, dull, glabrous, 11 – 13 × 4 – 5 cm, valve 3 mm thick, beak 1 – 3 mm long, sutures not winged; 2 – 2.5 longitudinal ridges running from the base to the apex, parallel to and at 0.3 – 2 cm distance to the upper suture

Note

Gilbertiodendron sulfureum is related to G. brachystegioides. It is a small to medium-sized tree from swamp forest, while G. brachystegioides is a large tree from forest on well-drained soil. The stipules are reniform, but flat; a pair of stipules is not strongly inrolled towards each other. The leaflets have an acumen of 0.5 – 2 cm long; not 0 – 1 cm long as in G. brachystegioides. The pedicel is 6 – 13 mm long; not 10 – 25 mm long. The dried bracteoles are light yellowish brown in colour, not dark brown in colour. The pods are 11 – 13 × 4 – 5 cm, not 12 – 19 × 5 – 7 cm as in G. brachystegioides.

Macrolobium brachystegioides var. sulfureum was published invalidly by Pellegrin (1941: 506). Specimens cited: Le Testu 5891, 5963, 8844, 9017, 9094, 9574, 9612. This taxon was not published in accordance with the Code: there is no Latin description. Although Pellegrin published the new taxon as a variety, he suspected the taxon to be a new species (Pellegrin 1941: 506, 1949: 52). Léonard (1954: 61) made the invalidly published taxon a synonym of Gilbertiodendron ogoouense, possibly because the stipules and flower buds resemble those of G. ogoouense rather than those of G. brachystegioides.

The species epithet of Gilbertiodendron sulfureum refers to the yellowish brown colour of the dried bracteoles.

Distribution

Gilbertiodendron sulfureum is known from Gabon and southern Cameroon (Map 13).

Ecology

Gilbertiodendron sulfureum occurs in periodically inundated evergreen rain forest and swamp forest, at 200 – 700 m asl.

Conservation

Gilbertiodendron sulfureum is assessed here according to IUCN criteria as Least Concern (Table 1). Being a small to medium-sized tree, the species is presumably only indirectly threatened by logging.