Greenwayodendronglabrum is morphologically similar to G.suaveolens but differs from it by the absence of trichomes on the petiole, midrib and lower and upper side of the leaf lamina.

CAMEROON. South region: 40 km from Kribi, 5 km E of Edea road, tract of Fifinda-Bella road (SFIA), 6 Feb 1970, J.J. Bos 6267 (holotype WAG! [WAG1433854]; isotypes (WAG! [WAG1433855]; YA)

Tree 7–30 m tall, d.b.h. 3–20 cm. Young branches sparsely pubescent trichomes ca. 0.1 mm long; old branches glabrous. Leaves: petiole 2.5–6.2 mm long, 1.0–2.2 mm in diameter, glabrous; lamina 6.5–16.2 cm long, 2.1–5.8 cm wide, length: width ratio 2.2–3.6; elliptic to narrowly elliptic, base rounded or cuneate, apex acuminate, aristate, apiculate or caudate, acumen 4–40 mm long, upper side glabrous, lower side sparsely pubescent to glabrous; midrib glabrous on the upper and lower side; secondary veins 5–7 pairs, upper side glabrous, lower side sparsely pubescent to glabrous, trichomes ca. 0.1 mm long; tertiary veins irregularly and indistinct above. Inflorescence axillary, a 1–4 flowered rhipidium. Floral buds ellipsoid, 4.0–4.5 mm long, 3.5–4.0 mm in diameter, densely covered with short trichomes. Flowering pedicel 3.5–4.0 mm long, 0.5–1.1 mm in diameter, sparsely pubescent covered with short trichomes, becoming glabrous, trichomes 0.1 mm long, lower bract in lower haft of pedicel, minute, densely pubescent, upper bract apical, just below the calyx, 2.0–2.2 mm in diameter, densely pubescent, trichomes 0.2–0.3 mm long. Sepals 3.0–3.1 mm long, 3.2–3.5 mm wide, length:width ratio ca. 0.9, broadly ovate, imbricate, fused at the base, apex acuminate, base truncate, densely pubescent outside, sparsely pubescent inside, trichomes 0.1–0.2 mm long. Inner and outer petals 12–13 mm long, 2.0–2.5 mm wide, length:width ratio ca. 0.9, narrowly ovate to narrowly elliptic, apex acuminate, base rounded; outside tomentose, trichomes ca. 0.3 mm long; inside sparsely pubescent to glabrous; glabrous part to 4.2–4.6 mm long; green maturing pale yellow. Male flowers: not observed. Hermaphrodite flowers: stamens 10–15 in a single whorl, appressed, 1.2–1.5 mm long and 0.3–0.4 mm wide, stamens tongue-shaped or lobulated in shape; carpels 10–15, 1.1–1.2 mm long, 0.5–0.6 mm in diameter, length:width ratio 2.8, narrowly oblong, densely pubescent; ovules 1–2, oblong; stigmata ovoid, densely pubescent, trichomes ca. 0.1–0.2 mm long. Fruiting pedicel 6–13 mm long, 1.3–2.2 mm in diameter, sparsely pubescent, trichomes ca. 0.2 mm long; stipes 4.5–10.2 mm long and 1.1–3.2 mm in diameter, glabrous; monocarps 2–8, 11.0–21.1 mm in diameter, broadly ellipsoid to globose, sparsely pubescent to glabrous, green turning wine red at maturity; seeds 1–4 per monocarp, 7.0–12.6 mm in diameter, ellipsoid to globose, flattened on one side or hemi-ellipsoid when more than one seed per monocarp, surface covered by a white tegument.

Distributed in south-western Cameroon and north-western and central Gabon; 20–750 m (Fig. 4).

A sub-canopy tree, in dense moist evergreen mature and secondary forests.

Flowering and fruiting are not well known. A flowering sample was collected in February and several fruiting samples were collected in November in Gabon and in February in Cameroon.

Unknown.

Unknown.

Least Concern [LC]. The extent of occurrence (EOO) of Greenwayodendronglabrum is estimated to be over 78,284.28 km², whereas its area of occupancy (AOO) is estimated to be 108 km² (which falls within the limits for Vulnerable status under criterion B2. The species, recorded from Gabon and Cameroon, is now known from at least 31 specimens representing 22 subpopulations. These 20 subpopulations represent 20 different locations (sensu IUCN 2012), many more than 10 locations, which are the upper limit for Vulnerable status under subcriterion ‘a’. Greenwayodendronglabrum has been collected in 3 protected areas in Cameroon (Campo-Ma’an National Park), Equatorial Guinea (Monte Alen Nation), Gabon (National Park of Crystal Mountains) and from unprotected areas. This taxon has a low relative abundance except in localities from the region going from the northwest of Gabon to the south of Cameroon where the relative abundance is high. The main threat to G.glabrum is its habitat destruction resulting from logging activities and intensive agriculture in Cameroon. Notwithstanding these human activities, with varying levels of impact, the species appears not as threatened as it is abundant. The available information suggests that the number of subpopulations and mature individuals of G.glabrum, as well as its EOO and AOO, will not decrease noticeably in the next ten years.

This species was found growing in sympatry with G.suaveolens in southern Cameroon. However, G.glabrum differs from other species of the genus by the absence of trichomes on the petioles, midrib and lower and upper side of the leaf lamina. Nevertheless, some specimens do present small isolated tufts of trichomes on the lower side of the leaf lamina. This general lack of pubescence was observed both in situ on fresh specimens (adults and juveniles) but also on herbarium samples. This species is also genetically distinct from G.suaveolens and other species in the genus based on DNA microsatellite data (Lissambou et al. in prep.) and a nuclear gene phylogenetic analysis (Couvreur et al. in prep).

Cameroon. South Province: 40 km from Kribi, 5 km E of Edea road, tract of Fifinda-Bella road (SFIA), 3°13'N, 10°04'E, 6 Feb 1970, Bos, J.J. 6267 (BR, P, WAG, YA,); Mvindi 35 km E of Campo, 2°24'N, 10°21'E, 19 Dec 1983, Kaji, M. 4 (YA, P); Left bank Nyong R., 30 km S of Edea, near [a/the] bridge on [a/the] road to Kribi, 3°33'N, 9°59'E, Leeuwenberg, A.J.M. 5582 (BR); Parc Campo MA’AN, 2°17.11572'N, 9°57.006'E, 17 Jan 2016, Lissambou, B.J. 1745 (BRLU); ibid. loc., 2°17.110'N, 9°56.812'E, 17 Jan 2016, Lissambou, B.J. 1755 (BRLU); ibid. loc., 2°17.5189'N, 9°56.730'E, 18 Jan 2016, Lissambou, B.J. 1807 (BRLU); Concession forestière Wishema, 2°24.446'N, 9°53.781'E, 19 Jan 2016, Lissambou, B.J. 1828 (BRLU); ibid. loc., 2°24.411'N, 9°53.698'E, 19 Jan 2016, Lissambou, B.J. 1830 (BRLU). Littoral: Near Ndogtima Nyong (15 km NE from mouthpiece Nyong) Edea, 3°23'N, 10°00'E, 3 Feb 1974, Letouzey, R. 12869 (BR, YA, P); Canton du Ntem, 16 km SW from Nyabessan, 2°48'N, 10°11'E, 30 Nov 1982, Nkongmeneck, B.A. 400 (YA, P).

Gabon. Estuaire: Tchimbele, 0°37.07'N, 10°23.57'E, 14 Feb 2010, Phillippe 83 (BRLU, LBV, MO). Moyen Ogooué: Lac Azingo. Grands lacs Moyen Ogooué, 0°28.66'S, 10°1.98'E, 16 Oct 2014, Lissambou, B.J. 0013 (BR, BRLU, L, LBV, MO, P); ibid. loc., 0°27.768'S, 10°5.2044'E, 17 Oct 2014, Lissambou, B.J.0014 (BR, BRLU, L, LBV, MO, P); ibid. loc., Lac Azingo. Grands lacs, 0°27.773'S, 10°5.238'E, 26 Oct 2014, Lissambou, B.J. 0015 (BR, BRLU, L, LBV, MO, P). Ngounié: Mabounié, forest on the south side of the N’gounié River, 0°43.116'S, 10°35.933'E, 15 Oct 2012, Bidault, E. 847 (BRLU, LBV, MO); Upper Waka area, ca.3 km road Mikanda Forestry Camp to Ekanga, 1°18'S, 10°50'E, 29 Mar 2004, Wieringa, J.J. 5129 (WAG). Ogooué Ivindo: South of Ayem; western border of Lopé-Okanda Reserve, 0°25'S, 11°30'E, 19 May 1992, McPherson, G.D. 15802 (BR, P).

Equatorial Guinea. Rio Muni, Centro-Sur: SW from Monte Alén National Park, on the Mosumo Ecofac transect at 500 m from the beginning of the ride, 1°30'N, 10°04'E, 10 Feb 2001, Senterre, B. 171 (BRLU, LBV, MO); SW from Monte Alén National Park, 200 m S of Transcito Ecofac de Mosumo at 1620 m from the start of the trail, 1°35'N, 10°03'E, 7 Mar 2001, Senterre, B. 697 (BRLU, LBV, MO).