Boehmeria conica C.J. Chen, Wilmot-Dear & Friis

Wilmot-Dear, C. M. & Friis, I., 2013, The Old World species of Boehmeria (Urticaceae, tribus Boehmerieae). A taxonomic revision, Blumea 58 (2), pp. 85-216 : 129

14. Boehmeria conica C.J. Chen, Wilmot-Dear & Friis — Fig. 12 ; Map 14

Boehmeria conica C.J.Chen, Wilmot-Dear & Friis in Chen et al. (2003) 173; (2005) 449. ― Type: A. Henry 12070 (holo K), China, Yunnan, Szemao .

Large subshrub or shrub, up to 4 m tall, often dioecious, sometimes monoecious; ultimate branches 4-angled, 2–2.5 mm diam, sparsely hairy, hairs fine, minute adpressed, soon glabrescent. Stipules narrowly triangular, 3–4 by 1.5 mm, connate at base. Leaves opposite, not or slightly dimorphic in size, ovate-orbicular to suborbicular or broadly ovate, 8–13(–17) by 6.5–12.5(–15) cm, length 1.2–1.5 × width, margin crenate, teeth 20–30 either side, shallow but very broad, 1–1.5(–2) by 3–6 (–10) mm, with width 3–5 × length; leaf apex consisting of a single long tooth, cuspidate to short-acuminate, rarely long-acuminate; base broadly cordate, rounded-truncate or rarely broadly cuneate, sometimes oblique; basal veins distinctly curved, extending into apical fifth of lamina (almost to apex in very broad leaves), upper lateral veins 2(–3) either side, lowermost arising just in distal half of lamina (on one side veins often fewer and nearer apex), finely prominent abaxially; coarser scalariform tertiary veins and reticulation visible abaxially; texture ± membranous; adaxial surface dark green when dried, hairy like the stem, soon glabrescent; abaxial surface light green, subglabrous; petiole very variable relative to lamina size, 4–11 cm, usually over half of lamina length, sometimes longer than lamina, indumentum like that of the stem. Flower­clusters borne on leafless axes, these ± erect axillary, 4–8 cm long, each with lateral branchlets throughout its length, these short (<half of length of main axis), spreading, unbranched and progressively and regularly shorter towards apex of main axis, some axes arising from upper leaf axils unbranched; some axes bisexual with female and bisexual clusters in apical part; bracts broadly triangular, conspicuous, 0.7–1 by 0.7–0.8 mm; clusters spaced 1–2 mm apart, male clusters 1.5–2 mm diam, with 1–c. 5(–c. 10) flowers, female clusters similar or rarely up to 3.5 mm, with up to 25 flowers; bracteoles inconspicuous, c. 0.4–0.5 mm long. Male flowers 4-merous, sessile; mature buds ± globose or depressed-globose, usually apiculate, c. 1 mm diam, tepals without dorsal appendages, sparsely hairy like stem. Female flowers with very slender stigma only 0.8–1.2 mm long. Fruiting perianth broadly ovoid, only 0.8–1.2 by 0.6–1 mm, markedly dorsiventrally compressed either side of the achene to form an indistinct marginal wing, base ± rounded, apex with very short beak; sparsely hairy like stem especially towards apex. Achene ovoid, slightly dorsiventrally compressed, occupying 0.7 × length of fruiting perianth, fawn.

Distribution ― North-eastern India, Nepal, Bhutan, Burma (not georeferenced and not shown on map), south-western China.

Habitat & Ecology ― Forest, often dense, shady wet places in ravines; (700–) 1200–2600 m altitude.

Conservation status ― Least Concern (LC). The species is known from c. 30 collections, many of which are recent. It occurs in locations along the Himalayas and their extension into southern China, and in fairly restricted forest habitat. The EOO is 505 840 km 2. Although the AOO gives a figure of less than 500 km 2; its localities in the Himalayas are not currently threatened by serious habitat degradation, and it therefore does not meet the criteria for a formal status of Vulnerable (VU).

Notes ― 1. This species is distinctive in its inflorescence-bearing axes of both sexes small, branched and having lateral branchlets progressively shorter towards the apex of the main axis, producing a markedly neat conical appearance, its leaves broad, thin-textured, crenate and often truncate and fruiting perianth small, relatively broad.

2. Boehmeria conica has been confused with B. polystachya (sympatric but not extending so far east) which differs in its inflorescence-bearing axes large, crowded, much more irregular, secondarily branched with large clusters bearing 40–50 flowers and its leaves narrower, thicker-textured, serrate, gradually acuminate, cuneate at the base, with secondary veins prominent close-spaced scalariform. Boehmeria polystachya also has larger bracts subtending its flower-clusters, stigma even shorter (0.3–0.6 mm long) and fruiting perianth relatively narrow with length c. 2 × (rather than at most 1.3 ×) width, tapering rather than rounded at the base.

3. The sympatric but more widespread B. virgata subsp. macrophylla can sometimes be confused with B. conica , since some variants have male axes of similar architecture, but differ in leaves relatively narrower usually thicker-textured with marginal teeth relatively much narrower usually acute and female inflorescence-bearing axes usually unbranched.

Figures

Map 14 Distribution of Boehmeria conica C.J.Chen, Wilmot-Dear & Friis (●), B. polystachya Wedd. (▲) and B. kurzii Hook.f. (ä).

Fig. 12 Boehmeria conica C.J. Chen, Wilmot-Dear & Friis. a. Habit of stem with inflorescence-bearing axes; b. male bud; c. male flower; d. fruiting perianth; e. fruit with perianth removed (a: Sino­Russian Expedition 1358; b, c: Tsiang 13400; d, e: Henry 12070; all PE). — Scale bars: a = 2 cm; b-e = 1 mm.