Mezoneuron benthamianum Baillon

Clark, Ruth P., 2016, A Taxonomic Revision of Mezoneuron (Leguminosae: Caesalpinioideae: Caesalpinieae), Phytotaxa 274 (1), pp. 448-450 : 448-450

2. Mezoneuron benthamianum Baillon

Adansonia 6: 196. 1866.

Type:—SENEGAMBIA: 1837, Heudelot s.n. Holotype P (P00374799!); isotype P!.

Synonym. Caesalpinia benthamiana (Baillon) Herendeen & Zarucchi. Ann. Missouri Bot. Gard. 77(4): 854. 1990.

Scandent shrub or liana to 10 m in length. Stems with scattered large recurved prickles, to ca. 1.5 cm, corky spine-tipped tubercles on older stems; glabrous or very sparsely orange tomentose. Stipules persistent, triangular, 1 × 1–3 mm, the margins tomentose. Leaves with 4–7 pairs pinnae; 4–6 pairs leaflets per pinna; petiole 2.5–7 cm; rhachis 7–26 cm, with recurved prickles in pairs at the pinna insertion points, and scattered on the internodes; pinnae 5–12 cm, sometimes with scattered recurved prickles at the leaflet insertion points, and scattered on the internodes; leaf rhachis, petiole, and pinna rhachis glabrous or sparsely whitish to orange tomentose. Leaflets alternate; the terminal leaflets obovate, base oblique, apex obtuse to retuse, 1.8–4.6 × 1–2.9 cm; lateral leaflets broadly oblong, base oblique, apex obtuse to retuse, 1.5–6 × 0.9–3.3 cm; all leaflets with both upper and lower surface glabrous, or sparsely tomentose, the hairs sometimes semi-appressed; 2˚ venation anastomosing, 3˚ venation reticulate, visible and slightly raised on both surfaces. Inflorescence a raceme or panicle, axillary or terminal, to 50 cm, the axis up to 1 cm wide at base; sometimes with recurved prickles scattered on the lower axes; densely greyish or fawn to orange tomentose on flower-bearing parts of racemes, basal portions lacking flowers are glabrous, or sparsely hairy; pedicels 6–13 mm, articulated ca. 2 mm below the hypanthium, sparsely to moderately whitish to orange tomentose, hairs denser around articulation. Bracts sometimes present, persistent, triangular, c 1–2 × 1–2 mm,

A TAXONOMIC REVISION OF MEZONEURON

Phytotaxa 274 (1) © 2016 Magnolia Press • 9 sparsely tomentose, or on the margins only; bracteoles caducous, elliptic, acuminate; 2 × 1 mm, sparsely tomentose, the acuminate apex glabrous. Flowers with a hypanthium ca. 2 × 6–9 mm; lower calyx lobe ca. 7–9 × 4–6 mm, other calyx lobes 5–8 × 2–4 mm; hypanthium and calyx lobes moderately to densely fawn to orange tomentose on outer surface, inner surface sparsely tomentose. Median petal blade obovate, claw oblong, laterally inrolled, with a transverse flap of tissue on inner surface between claw and blade, 9–10 × 6–9 mm, the flap of tissue sparsely hairy, hairs on the margins of the blade and claw. Upper lateral petals broadly elliptic to suborbicular, 7–9 × 7–8 mm, including claw 1 mm long; inner surface of claw pilose, petal otherwise glabrous. Lower lateral petals elliptic to suborbicular, 7–10 × 6–7 mm, including claw 2 mm long; inner surface of claw sparsely pilose, petal otherwise glabrous. Stamen filaments 10–18 mm long, tomentose on inner surface, along the basal ¼ - ½ of length. Ovary 5–7 mm long, style 11–16 mm long, ovary densely fawn, greyish or pinkish tomentose, style glabrous or with few hairs; stigma funnel-shaped, to 2 mm wide, the rim papillate. Fruit oblong, base cuneate, apex rounded, sometimes with the central vein extending to form a beak; 8–10.7 × 2.3–2.9 cm, wing arising basally 1–5 mm along central vein, 4–7 mm wide; fruit surface sparsely to moderately tomentose, densely so when young; veins clearly visible on body, slightly or clearly in wing; pink when mature; hypanthium persistent. Seeds 2–4 per fruit; oval in outline and clearly visible when mature under the raised surface of the fruit body.

Distribution:— Senegal, Gambia, Guinea-Bissau, Guinea-Conakry, Liberia, Ivory Coast, Ghana, Togo, Nigeria ( Fig. 3).

Habitat and ecology:—Forest, scrub, savannah. Elevation to 900 m.

Phenology:—Flowering November–April, fruiting December–April

Preliminary conservation assessment:—Extent of Occurrence 1,399,533.101 km 2 = LC; Area of Occupancy 136.000 km 2 = EN.

Category assigned:—Least Concern (LC).