Boehmeria rugosissima (Blume) Miq.

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 : 197-199

31. Boehmeria rugosissima (Blume) Miq. — Fig. 37; Map 39

Boehmeria rugosissima (Blume) Miq.(1851) 32. ― Urtica rugosissima Blume (1825) 490. ― Boehmeria platyphylla D.Don var. rugosissima (Blume) Wedd. (1856) 366. ― Boehmeria caudata (Burm.f.) J.J.Sm. var. rugosissima (Blume) J.J.Sm. (1910) 711. ― Type: Herb Reinwardt 1691 (lecto L, selected here); Herb Reinwardt s.n. (possible isolecto L), Jawa [Java], “in fruticetes montosis”. – See Note 1.

Shrub, 1.5–3 m tall; ultimate branches 1.5–2.5 mm diam, hairs sparse or abundant, usually spreading, fine, short or long (≤ 0.5 m) or of mixed length. Stipules narrowly triangular free to base, often very large and conspicuous, 10–25 by (2–) 3–5 mm, thin- or thick-textured, soon caducous from second or third node. Leaves opposite, scarcely dimorphic or ‘larger’ ones up to 2.5 × length of ‘smaller’ ones, not or slightly asymmetrical, broadly ovate, somewhat variable in size and relative proportions, usually at least some on plant large, 13–25 by (6–) 8–20 cm (rarely none over 9 by 5 cm), length 1.3–2.3 × width; margin up-curved-serrate or crenate-serrate, teeth 35–70 either side, very shallow even on large leaves, 1–2 by 2.5–4 mm, often becoming indistinct towards base; leaf apex attenuate-acuminate, short and broad; base narrowly rounded to slightly cuneate but usually slightly cordate at extreme base; basal veins extending into distal third, upper lateral veins on one side 3 – 5, lowermost arising near middle of lamina, 2–4 on other side, all arising in distal half of lamina, impressed but often rather inconspicuous adaxially, usually prominent abaxially, coarser lateral venation often similarly prominent; texture usually thickly chartaceous (some large-leaved forms thin-chartaceous) and leaves always bullate, but bullation in large leaves sometimes reduced to small projections on adaxial surface in the centre of each areole (with corresponding depression in abaxial surface), drying markedly brownish; adaxial surface with single ± spreading hair in centre of each bullation, later glabrescent with slight bulbous base of hair remaining, abaxial surface with hairs sparse to abundant, short, fine and spreading, and/or with coarse longer hairs on veins only; petiole very variable relative to lamina length, 1.3–16 cm, 0.1–0.5 × (rarely almost equalling) lamina length. Flower­clusters partly axillary but mostly borne on leafless axes c. 6–15 cm long and arising one from each axil but almost always with a few long branches from basal half, some of these often so close to base as to appear several axes per axil, unisexual, the male axes sometimes with 2nd-order branching; axes often drooping near apex; bracts 2–3 by 1–1.5 mm, short and broad but with long-acute apex; clusters spaced (1–) 2–4 mm apart, up to 3(–4) mm diam, male clusters with 2–10 flowers; female clusters with 15–20(–30) quite densely crowded flowers; bracteoles inconspicuous. Male flowers 4-merous, subsessile or with pedicel up to 0.5(–1) mm long, mature buds depressed-globose, c. 1.3 mm diam, dorsal appendages distinct, hairs abundant, spreading, relatively coarse. Female flowers 0.6–1 by 0.3–0.5 mm, ovoid or ellipsoid, abruptly slightly tapering at apex but ± without beak (apical teeth sometimes conspicuous) and not truncate, hairy as male; stigma (0.5–) 1–2 mm long, straight or hooked. Fruiting perianth 0.8–1.2 by 0.5(–1) mm, ovoid, ellipsoid or obovoid, slightly dorsiventrally flattened with slight marginal ridge or more markedly with slight winged shoulders, apex acute, hairs sparse or abundant, conspicuous, robust, spreading. Achene almost filling fruiting perianth, yellowish brown.

Distribution ― Indonesia (Sumatera, Jawa, northern Sulawesi), Philippines (Mindoro, Mindanao).

Habitat & Ecology ― Evergreen forest, disturbed or cultivated areas; 450–1600 m altitude.

e

g

h

Fig. 37 Boehmeria rugosissima (Blume) Miq. a. Habit of stem with young inflorescence-bearing axes, branched at base; b. detail of stem with pair of mature inflorescence-bearing axes;c, d. leaves from different plants;e, f. leaf ,detail of margin and adaxial surface; g. leaf,detail of abaxial surface; h. detail of stem and stipule; i. portion of young male inflorescence-bearing axis with densely congested flower-clusters (inflorescences) and bracts; j. male bud; k. portion of female inflorescence-bearing axis with flower-clusters (inflorescences) and bracts; l. female flower; m, n. fruiting perianths from same plant (a, e - g, i: Lanjouw 103; b, j: Beccari 281; c, h: Morley 21; d, k, l: Koorders 31831B; m, n: Bunnemeijer 8122; all K). — Scale bars: a - d = 2 cm; e = 5 mm; f - i, k = 2 mm; j, l - n = 1 mm.

Conservation status ― It is uncertain whether this species should be assessed as Near Threatened (NT) or Vulnerable (VU). It is known from over 80 collections but rather few are recent and it appears to occur in only ten widely scattered localities. In the Philippines and some areas near Manado (Menado) habitat is severely degraded but in the mountain ridges in Indonesia it may be less at risk. Tentatively it is given the status of Vulnerable (VU) on the criteria B2ab(iii).

Notes ― 1. Our choice of lectotype of B. rugosissima : Although no collection number is cited in the original description, one collection has been traced which bears the handwritten annotation “ Urtica rugosa R.” This collection is selected as lectotype as being one of only two specimens from Herb. Reinwardt ; it is an adequate specimen for typification and it seems reasonable to assume that this was part of the material Blume saw. He would not have been able to use Reinwardt’s preliminary label name, since the name Urtica rugosa was already occupied by Urtica rugosa Sw. (1787: 60) . The other sheet from Herb. Reinwardt lacks the epithet on the label but is otherwise so similar that it may well be a duplicate collection from a different part of the same large plant.

2. This is a species of narrow geographical distribution, mainly Sumatera and Jawa and just reaching the southern Philippines, from which only two collections of certain identity have been seen. It is distinctive in its leaves bullate, usually large, broad and thick-textured, drying dark brownish adaxially but often much paler chestnut-brown abaxially, and its large conspicuous stipules.

3. It can be confused with thick-leaved forms of B. virgata var. virgata (sympatric but widespread) which differs in stipules almost always smaller, female inflorescence-bearing axes often> 30 (rather than ≤ 15) cm long, achene small relative to fruiting perianth and leaves mostly relatively narrower with apex usually attenuate. Of the very few collections of the two taxa seen from the Philippines, two collections from Mindanao ( Ramos et al. 38857, 39190) are intermediate and impossible to assign to either taxon.

4. Forms of B. pilosiuscula (partly sympatric) with large thick leaves can be very difficult to distinguish from small-leaved forms of B. rugosissima . Differences are as follows: In B. pilosiuscula flowers and fruiting perianth are always truncate at apex (and at least fruiting perianth often with an abrupt distinct beak, distinctly flattened and winged in apical part), and female inflorescence-bearing axes (especially in Jawa) usually have a few male clusters at the apex. There is slight overlap in other characters: leaf length 3–15 cm (in B. rugosissima is (9–) 13–25 cm); stipules 4–12 by 1–2.5 mm (even in small-leaved forms of B. rugosissima usually broader and longer, 10–25 by (2–) 3–5 mm); leaves of B. rugosissima dry rather blackish adaxially and at least small-leaved forms are thick-textured and strongly rugose with the adaxial surface consisting entirely of narrow conical bullations with no space between (all these characters are rare in B. pilosiuscula ). Large leaves of B. rugosissima may be thin-textured and shallowly bullate, but such leaves are very much larger than any seen in B. pilosiuscula . In B. pilosiuscula at least female axes are always short 1–6(–10) cm, clearly single and unbranched whereas axes in B. rugosissima are 6 –15 cm and usually branched, whereas in B. pilosiuscula upper veins are scarcely distinct from coarser tertiary veins and lamina is often elliptic or elliptic-obovate and at least some leaves often markedly asymmetrical due to the different outline of the two sides, whereas in B. rugosissima lateral veins are clear and prominent and lamina is clearly ovate and almost symmetrical.

The two taxa are apparently sometimes found growing together as mixed collections also exist (Jawa: Korthals s.n. (L); Reinwardt s.n. 1855 (P); Zollinger 1795 (U)). A few somewhat intermediate collections of possible hybrid origin have also been seen and found impossible to assign satisfactorily to either species, with leaves like B. pilosiuscula (slightly bullate) but inflorescence-bearing axes looser (unbranched) with well-spaced flower-clusters.

5. Boehmeria rugosissima is rather similar to some forms of the Hawaiian endemic B. grandis , the leaves of which are also large, thick-textured with prominent veins and drying brownish, but which differs in many (6–10) veins in the distal half of the lamina and several almost equally prominent coarse tertiary veins arising lower on midrib and in its fruiting perianth usually clearly winged with relatively small achene; stipules are also mostly much larger and broader. It can also be confused with the partly sympatric (but more widespread) B. virgata subsp. macrophylla var. scabrella which can have bullate leaves but has smaller stipules (7 mm long or less), leaves with more numerous hairs, usually drying greenish, often thin-textured.

6. The conspicuous stipules are very like those of Cypholophus anisoneurus ( Solomon Islands and Vanuatu), a taxon hitherto included in this genus, which also has large leaves, but these are thin-textured drying light greenish brown, usually strongly asymmetrical and with vein arrangement very different in the two sides; it also has female clusters in leaf axils rather than on long axes.

Figures

Map 39 Distribution of Boehmeria rugosissima (Blume) Miq.