Phyllanthus clarkei Hook.f.

Verwijs, J. I. M., Bouman, R. W. & Welzen, P. C. van, 2019, A taxonomic revision of Phyllanthus subgenus Macraea (Phyllanthaceae), Blumea 64 (3), pp. 231-252 : 237

3. Phyllanthus clarkei Hook.f. — Map 3

Phyllanthus clarkei Hook.f. (1887) 297; A.M. Cowan & Cowan (1929) 117; Croizat (1940) 650; Airy Shaw (1972) 317; R.L. Mitra & Sanjappa (2003) 13; Chantar. (2007) 483; P.T.Li & M.G.Gilbert (2008) 181; Chakrab. & N.P.Balakr. (2009) 527; (2018) 338. — Diasperus clarkei (Hook.f.) Kuntze (1891) 601. — Lectotype (designated by Mitra & Sanjappa 2003): C.B. Clarke 25420 (K (K000246582);iso BM (BM000951413), K (K000246581, K000246583)), India, Sikkim Himalaya at Catsuperri.

Phyllanthus simplex Retz. var. tonkinensis Beille (1927) 578. — Syntypes: Balansa s.n. (probably in P,not traced) Tonkin Cho-bo (black river), Vietnam; Poilane s.n. (probably in P, not traced) Ban-sa-noi, Ba-na-punk, Vietnam .

(Sub)shrubs, up to 120 cm high, monoecious; branches terete, not winged, scabrid to puberulous; internodes 2–7 mm long. Stipules ovate-triangular, 1.5–2.4 by c. 0.8 mm, persistent, brown when dry, base bilaterally auriculate, margin fimbriate, apex caudate. Leaves: petiole 1–1.5 mm long, glabrous; blade obovate, sometimes elliptic, 7–22 by 4–12 mm, 1.2–2.4 times longer than wide, membranous, base cuneate-attenuate,margin entire, plane to revolute, apex rounded to revolute, mucronate, dark green above, light-green underneath; midrib flat above, prominent underneath, lateral veins 4–5 per side, barely visible above, clear underneath. Staminate flowers 1–3 together, 1.5–2.5 mm diam; pedicel 1–3 mm long, glabrous; sepals 6, obovate, 0.8–1.2 by 0.5–0.9 mm, apex acuminate; disc glands 6, flat, circular, c. 0.2 mm diam, thin, smooth; stamens 3, 0.7–1 mm long, filaments free, 0.5–0.8 mm long, thecae globular, 0.2–0.3 mm long. Pistillate flowers solitary, rarely in pairs, 1.5–2.5 mm diam; pedicel 2–4 mm long, glabrous; sepals 6, obovate, 1–1.2 by 0.5–0.6 mm, apex obtuse; disc annular, slightly cupuliform, 6-lobed, c. 1.2 mm diam, 0.2–0.3 mm high, smooth; ovary subglobose, c. 1 mm diam, c. 0.9 mm high, each locule with a groove, glabrous; stigmas 3, c. 0.8 mm long, bifid for half of length. Fruits globose, 2.2–3.2 mm diam by c. 2.5 mm high, 6-grooved, green, turning black when dry, glabrous; pedicel 3–9 mm long, stigmas and sepals persistent; columella c. 1.2 mm long. Seeds trigonous, c. 2.2 by 1.1 mm, smooth when young, then verrucate along longitudinal lines, verrucae circular.

Distribution — India, Sri Lanka, Nepal, Myanmar, China, Thailand and Vietnam.

Habitat & Ecology — Open, rocky ground, found in pastures, sometimes on limestone ridges.Altitude: 900–2300 m. Flowering and fruiting all year round.

Vernacular name — Thailand: Mayom doi (มะยมดอย) ( Chantaranothai 2007).

Notes — 1. This species is closely related to other species of subg. Macraea according to the phylogeny of Luo et al. (2011). Morphological characters such as its non-phyllanthoid branching and staminate flowers with free stamens confirm that this species should be placed in subg. Macraea .

2. A similar species was described by Chakrabarty & Gangopadhyay (1993) as P. sanjappae . This species has not yet been included in any pollen or phylogenetic study and the staminate flowers are not known, so it is difficult to place this species in subg. Macraea with full certainty. Phylanthus sanjappae is distinct by its glabrous branchlets, sessile leaves with a mucron and the presence of a short style under the stigmas. However, the leaves of P. clarkei can also be mucronate and the indumentum is variable.

3. This species was confused by Hooker (1887) with P. parvifolius Buch.-Ham. ex D.Don and is also similar to P. pseudoparvifolius . A detailed study into the identity of these species was done by Mitra & Sanjappa (2003). Phyllanthus clarkei can be distinguished from P. parvifoliu s and P. pseudoparvifolius by its branching floriferous shoots, completely free stamens and longer fruiting pedicels ( Mitra & Sanjappa 2003).

4. Map data was supplemented with data from Gbif.org. Coordinate data can be accessed via https://doi.org/10.15468/ dl.uv7ddr.

Figures

Map 3 Distribution of Phyllanthus clarkei Hook.f. in SE Asia main land.