Mezoneuron sinense Hemsley

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

15. Mezoneuron sinense Hemsley

J. Linn. Soc., Bot. 23: 204. 1887.

Type:— CHINA: Hupeh, Ichang, Henry, A. s.n.

Lectotype:— Henry, A. 3113, K (K000264688!), Larsen et al. 1980.

Synonym. Caesalpinia sinensis (Hemsley) J.E. Vidal. Bull. Mus. Natl. Hist. Nat. , ser. 3, 395 (Bot. 27): 90. 1976.

Synonym. Mezoneuron sinensis var. parvifolium Hemsley. J. Linn. Soc., Bot. 23: 205. 1887.

Holotype:—Hupeh Province, Ichang, Henry, A. 2238, K (K000264687!), P (P00751902!).

Synonym. Caesalpinia stenoptera Merrill. J. Arnold Arbor. 19: 35. 1938.

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CLARK

Type :—INDO-CHINA: Tonkin, Jun. 1933, Petelot, A. 4757, NY .

Synonym. Caesalpinia tsoongii Merrill. Philipp. J. Sci. 27: 162. 1925.

Type :— CHINA: Szechuen, Tsoong 4190. Holotype UC; isotype GH.

Synonym. Caesalpinia chinensis Roxb. in Fl. Ind. ed. 2: 361. 1832., nom. rej. Li et al. Taxon 51: 816. 2002.

Type:—“Introduced from China, into the Botanic Garden at Calcutta, where it has now been for these five or six years and has not yet blossomed”

Scandent shrub or vine to 40 m in length. Stems with scattered recurved prickles to 4 mm; glabrous or sparsely whitish to pale orange tomentose. Stipules persistent, triangular, ca. 1–3 × 1–2.5 mm, glabrous, or the margins tomentose. Leaves with 2–4 pairs pinnae; 2–4 pairs leaflets per pinna; petiole (1.3–) 3–7 cm; leaf rhachis 7–31 [–40] cm, with paired recurved prickles at pinna insertion points, and scattered on the internodes, sometimes densely; pinnae 2.5–12.5 cm, sometimes with recurved prickles in pairs at the leaflet insertion points and sometimes scattered on the internodes; leaf rhachis and petiole glabrous to sparsely whitish to pale orange tomentose; pinna rhachis glabrous to sparsely pale orange tomentose. Leaflets opposite, elliptic, base cuneate to rounded, sometimes oblique, apex acute to rounded; terminal leaflets 3.5–10.5 × 1.3–5 cm; lateral leaflets 3.5–9.6 × 1.5–4.7; 2˚ venation anastomosing, 3˚ venation reticulate, veins faintly visible above, raised and clearly visible below; all leaflets glabrous both surfaces, or lower surface sparsely orange tomentose at base and on midvein, sometimes at margins, glossy above. Inflorescence a panicle, axillary, supra-axillary or terminal, 8–42 cm, axes sparsely to densely ferruginous tomentose, sometimes with small recurved prickles; pedicels 4–12 (– 14 in fruit) mm, articulated 1–2 mm below hypanthium, constricted at articulation, sparsely to moderately ferruginous tomentose, hairs denser at articulation. Bracts caducous, triangular, 0.5–2 × 1–1.5 mm, glabrous to moderately tomentose; bracteoles caducous, 2–3 × 1 mm, elliptic, acute, outer surface moderately to densely orange tomentose, hairs denser at margins, inner surface glabrous; clusters of triangular scale-like bracts sometimes below base of raceme. Flowers with a hypanthium 1–2 × 3–5 mm, sparsely to moderately ferruginous tomentose; lower calyx lobe 6–8 × 3–5 mm; other lobes 5–6 × 2–3 mm; all lobes sparsely to densely pale orange to ferruginous tomentose on inner and outer surface. Median petal obovate, sometimes reflexed backwards, inrolled, 6–9 × 3–5 mm, including claw 1–2 mm long, circular patch of orange hairs between claw and blade, hairs on margins of claw. Upper lateral petals obovate, 5–10 × 3–6 mm, including claw ca. 1 mm long, petal glabrous or with few hairs on inner surface of claw. Lower lateral petals 5–10 × 2–6 mm, including claw ca. 1 mm long, petal glabrous or with few hairs on inner surface of claw. Stamen filaments flattened, 5–14 mm long, densely orange villous on the basal ½ on inner surface; anther 1–2 mm long. Ovary 2–5 mm long, sparsely to densely, sometimes partially, orange tomentose, occasionally glabrous, style 7–12 mm long, sparsely hairy on basal part of length; stigma funnel-shaped, ca. 1 mm wide, not or only very slightly papillate. Fruit ligneous; suborbicular, straight along upper suture, to lunate, base cuneate to rounded, not stipitate or stipe 1 mm or less, apex with the wing and central vein extending to form a beak 0.1–2.5 cm long; (2.5–) 3–5.5 × 1.9–3.6 cm × ca. 3–5 mm deep, wing 0.5–3 mm wide; fruit surface sparsely ferruginous tomentose, hair densest at base and on margins, glabrescent; venation reticulate, raised and clearly visible on fruit body, no venation visible on the wing; hypanthium semi-persistent. Seeds 1 per fruit; ca. 2 cm diameter, not visible in outline on fruit exterior.

Distribution:— China, Myanmar, Thailand, Laos, Vietnam. ( Fig. 17 ).

Habitat and ecology:—Forest; thicket; limestone. Elevation 100–1500m.

Phenology:— China: flowering March–May, fruiting March–October. Vietnam, Laos: flowering March, fruiting June–August.

Preliminary conservation assessment:—Extent of Occurrence 837,078.951 km 2 = LC; Area of Occupancy 40.000 km 2 = EN

Category assigned:—Least Concern (LC). However, the species occurs within a fairly restricted area, and if found only on limestone then its potential habitat is limited.

A TAXONOMIC REVISION OF MEZONEURON

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Figures

FIGURE 17. Distribution of M. sinense in South East Asia.