Boehmeria virgata var. virgata

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 : 155-157

a. var. virgata — Fig. 21 ; Map 23

Urtica celebica Blume (1825) 492. ― Boehmeria celebica (Blume) Blume (1857) 217. ― Boehmeria platyphylla D.Don var. celebica (Blume) Wedd. (1869) 211. ― Boehmeria caudata (Burm.f.) J.J.Sm. var. celebica (Blume) J.J.Sm. (1910) 709. ― Type: Blume s.n. (holo L), Indonesia, Sulawesi.

Boehmeria erythropoda Miq. in Zollinger (1854) 101, 104. ― Type: Zollinger 534 (holo U), Indonesia, Jawa [Java],shady woods near Lamadjang, Tenga .

Boehmeria microcarpa Wedd. (1854) 201. ― Boehmeria platyphylla D.Don var. microcarpa (Wedd.) Wedd. (1856) 366, 369. ― Type: Labillardiere s.n. (lecto G, selected here; isolecto P), Indonesia, Sulawesi, Bouton Island . – See Note 1.

Boehmeria platyphylla D.Don var. marquesensis F.Br. (1935) 49. ― Type: Brown 986 (holo BISH), Marquesas Islands, Uapou, 25 Febr. 1922. – See Note 2.

Scandent or erect shrub or slender tree, 1–8 m tall, with trunk up to 30 cm diam, often with drooping branches; stems glabrous or with pale or brownish sparse adpressed closely-adpressed fine hairs or hairs dense, coarser, half-adpressed to spreading. Stipules up to 10 by 2 mm (up to 25 by 4 mm in Southeast Polynesia), glabrous or adpressed-hairy abaxially on midrib or (New Guinea) whole surface. Leaves almost symmetrical or two sides dissimilar; ‘larger’ leaves (5–)10–22 by 3–12 cm, length 1.8–3.5 × width; marginal teeth (20–)25–45 either side, rounded or acute but not or scarcely up-curved, indistinct or distinct, (0.2–)0.5–1 by 2–4.5 mm (–2 by 7 mm in Southeast Polynesia and New Guinea); leaf apex gradually short-attenuate with fine tip; base broad-cuneate to narrowly rounded; upper lateral veins on one side 1–3 (up to c. 7 in Southeast Polynesia), often only basal vein visible (impressed) adaxially, lateral veins and coarser often ± scalariform tertiary veins finely prominent abaxially; texture thin- or thick-chartaceous, adaxial surface often somewhat shiny with prominent minute cystoliths, glabrous or with very sparse ( Indonesia, abundant) hairs, short, fine, straight, closely-adpressed, usually lying in pattern pointing towards centre of areoles, or (New Guinea, forms somewhat intermediate with var. velutina ) sparse longer half-adpressed soft wavy hairs giving rough feel to leaf; abaxial surface with hairs on veins only or whole surface, sparse close-adpressed or ± spreading; petiole usually 0.3–0.5 × lamina length. Male inflorescence-bearing axes 10–20 cm with short lateral branches usually throughout length; female (or mainly female) inflorescence-bearing axes 20–70 cm, and of varying form, in the Pacific usually unbranched or with a few short lateral entirely male branches near base, in New Guinea these lateral branches entirely female, more numerous, longer and sometimes with 2nd-order branching, in Maluku and Sulawesi with 1st-order branching throughout length; clusters crowded or well-spaced. Male flowers almost glabrous or ( Indonesia) with sparse coarse hairs. Fruiting perianth with a wide range of shape, ovoid-conical or ellipsoid to obovoid or obtriangular in outline but always with a distinct often broad wing.

Distribution ― Malaysia (Selangor), Philippines (Luzon, Bohol, Mindanao), Indonesia (a few records to the west of Wallace’s line: Sumatera, Jawa and Bali, east of this line as for the species), Papua New Guinea, Pacific (incl. Solomon Islands,

Vanuatu, Fiji, Tonga Islands, Samoan Islands, Society Islands, Marquesas Islands, Austral Islands).

Habitat & Ecology ― As for the subspecies as a whole.

Conservation status ― Least Concern (LC). Widespread in a wide range of habitats and presumed often abundant. Over 400 collections, many recent, have been seen clearly referable to this widespread variety.

Notes ― 1. No type collection was cited for B. microcarpa Wedd. in 1854 (only “Ins. Molucc.”) but Weddell (1856: 369) cites for var. microcarpa and var. moluccana several collections including this one: “η & θ Labillardiere, Blume, D’Urville, Milne ” and the Labillardiere sheet at G has the epithet microcarpa in Weddell’s hand.

2. The variation within this variety and its relationship with the rest of the species are discussed fully under the species as a whole (Notes 2–4).

3. This variety is one of only two Boehmeria taxa native to the Pacific (the other being the Hawaiian B. grandis with which it sometimes appears ± intermediate as discussed below (Note 5). It is extremely variable in leaf-size, relative proportions and texture, sometimes also in stipule length (Southeast Polynesia), specimens at the extremes of variation looking very different; this variation is partly correlated with geographical distribution but in each region a range of intermediates with more ‘typical’ material also occurs. For this reason variants from Southeast Polynesia (Marquesas Islands and Tahiti) with unusually small leaves and only moderately flattened indistinctly winged fruiting perianth, which were described as var. marquesensis , are not formally distinguished here.

4. Boehmeria virgata var. virgata is so variable that it has often been confused with four other species of Boehmeria . It can be rather similar vegetatively to one or other variety of B. densiflora the allopatric var. boninensis (Bonin and Ryukyu Islands) and the partly sympatric var. densiflora ( China, Japan and sympatric in the Philippines). In flower or fruiting perianth both varieties are easily distinguished from B. virgata var. virgata by female inflorescence-bearing axes erect, densely congested, often short and male axes unbranched with usually contiguous clusters. Forms of var. virgata from Fiji with thick-textured leaves and acute rather than acuminate leaf apex are vegetatively rather similar to B. densiflora var. boninensis . Var. virgata is usually easily distinguished from var. densiflora in having leaves larger, relatively broader ± glabrous adaxially; however, without flowers certain Indonesian variants with leaves small, narrow, thin-textured, abundantly adpressed-hairy adaxially, can only be distinguished from B. densiflora var. densiflora by spreading rather than adpressed hairs abaxially and tertiary venation clearly scalariform and fairly conspicuous. (See further discussion under B. densiflora as a whole.)

5. Certain other, very different, variants found in Southeast Polynesia (Tahiti and Rapa) with large stipules (> 10 mm long) and leaves large, broad, thick-textured with 4–7 upper veins are strikingly similar to forms of the allopatric but ‘neighbouring’ B. grandis (Hawaii) with large sparsely hairy leaves. Small-leaved variants of the two taxa are fairly easily distinguished (in B. grandis they have marginal teeth 1–2 mm long, in B. virgata var. virgata much shorter) but in large leaves the size range of teeth overlaps. However, leaves of these particular variants of B. virgata are mostly crenate and smooth with inconspicuous fine reticulation, whereas leaves of B. grandis are always serrate and large ones usually bullate due to close-spaced adpressed robust reticulate veins which are impressed adaxially, prominent abaxially. Boehmeria grandis is easier to distinguish in flower and fruit, differing in inflorescence-bearing axes always branched, the male ones secondarily branched. A few collections (e.g., Tahiti, Florence 3854, P and Rapa, St. John 15359, A) appear entirely intermediate and it is possible that these variants of B. virgata , from the eastern extreme of its distribution and closest to the distribution of B. grandis ) may represent an intermediate between the two taxa.

6. Certain variants from Indonesia and Philippines with leaves broad and large-toothed, relatively hairy abaxially can be confused with less bullate forms of the partly sympatric but less widespread B. rugosissima ( Indonesia mostly west of Wallace’s line and Philippines). Boehmeria rugosissima differs from these variants in stipules almost always larger, inflorescence-bearing axes ≤ 15 cm long, achene almost filling fruiting perianth and leaf apex more distinctly acuminate, but two collections impossible to place in either taxon have been seen from Mindanao (discussed under B. rugosissima ).

7. Most forms of var. virgata are easily distinguished from B. multiflora ( Philippines and Sulawesi) by leaves larger and relatively broader, adaxially glabrous or adpressed-hairy, but variants from Indonesia with leaves relatively narrow and spreading-hairy can be confused with it. Boehmeria multiflora is distinguishable by inflorescence-bearing axes unbranched mostly shorter and leaves narrower usually bullate with length ≥ 3 × width (rather than, in this form at least, only up to 2.5 × width), basal veins scarcely extending to the distal half of lamina and marginal teeth often relatively narrower.

8. Forms with leaves ± glabrous, thin-textured and crenate can be confused with the widespread B. zollingeriana where the diagnostic male flowers are lacking.

9. Var. virgata often has leaves long, narrow and asymmetrical in outline, which leads to confusion with the genus Cypholophus and especially with C. decipiens which has female clusters simple, axillary, stigma minute, curved and fruiting perianth succulent (see discussion in Wilmot-Dear & Friis 1998: 920–921). The distribution of C. decipiens overlaps in Papua New Guinea (where it is not easily confused with the relatively broad-leaved long-toothed regional variants of var. virgata found there) and Melanesia (Bougainville and Vanuatu), where B. virgata is narrower-leaved and less easily distinguished. Vegetative differences are not absolute but C. decipiens always has leaves narrow, closely-finely-serrate (tooth width often equalling length) drying dull greyish brown or blackish brown (rather than usually greenish or yellow-brown), often markedly asymmetrical and sideways-curved at the apex and with the upper lateral veins on the two halves usually very dissimilar, 3–5 and 0–2, respectively, (rather than usually 1–2 and 0–2). (The many-veined variants of var. virgata found in Southeast Polynesia would not be confused with C. decipiens as their leaves are relatively broader, ± symmetrical and veins similarly arranged on both halves of the lamina.)

Figures

Map 23 Distribution of Boehmeria virgata (G.Forst.) Guillem. subsp. virgata var. virgata.

Fig. 21 Boehmeria virgata (G.Forst.) Guillem. subsp. virgata var. virgata. a. Habit of stem with inflorescence-bearing axes; b. detail of one node showing dimorphic leaf-pair; c. leaf, detail of adaxial surface; d–f. leaf, detail of margin and abaxial surface (from different plants); g. detail of stem and stipules; h. male bud; i. fruiting perianth (a, g, h: Smith 8761; b: Christofferson 3070; c, d, i: Kostermans 6362a; e: Degener 15008; f: Johanis 5248; all K). — Scale bars: a, b = 2 cm; c-g = 2 mm; h, i = 1 mm.