Boehmeria virgata (G.Forst.) Guill.

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 : 147-153

23. Boehmeria virgata (G.Forst.) Guill. — Fig. 21–29 ; Map 23–30

Boehmeria virgata (G.Forst.) Guill. (1837) 182. ― Urtica virgata G.Forst. (1786) 66, no. 345. ― Boehmeria taitensis Wedd. (1854) 200, nom. illeg. superfl., based on Urtica virgata G.Forst.(1786) . ― Boehmeria platyphylla D.Don var. virgata (G.Forst.) Wedd. (1856) 366. ― Type: G. Forster s.n. (iso K), the locality indicated is “Society Islands” in the protologue, but the K isotype material indicates two localities on the label: “Tongo Tabo, Taheetee” [ Tonga Tapu,main islands in the Tonga Islands, and Tahiti,main island in the Society Islands].

Erect or scandent subshrub, shrub or tree (rarely woody-based herb), 0.5–8 m tall; ultimate stems fairly robust, 1.5–2 mm diam, soon becoming thicker and woody, with widely varying indumentum, hairs sparse, inconspicuous, adpressed short, stiff or fine, or dense, spreading longer and soft. Stipules narrowly triangular mostly rather small and inconspicuous, ± free to base, 4–6(–11) by 1(–2.3) mm, thin- or thick-chartaceous, hairy outside or sometimes glabrescent. Leaves mainly opposite (sometimes some on ultimate lateral branchlets alternate), with laminas not or only slightly dimorphic in size and shape but petioles often more markedly dissimilar; lamina ovate to rhombic-ovate or elliptic, with wide range of size and relative proportions, (5–)10–24 by 3–16 mm, length (1.2–)1.5–3.5 × width; almost symmetrical or slightly asymmetrical especially at base and apex; margin regularly toothed throughout length, teeth widely varying in number, size and shape, minute and indistinct or large and conspicuous, rounded or narrow-acute, 10–60 either side, (0.2–)1–4(–7) mm long; leaf apex attenuate or distinctly acuminate, toothed to tip or consisting mainly of a single long terminal tooth; base slightly or markedly asymmetrical, cuneate to narrowly or broadly rounded, rarely ± truncate or slightly cordate; basal veins extending into distal half or well into distal third of lamina, upper lateral veins 1–3(–[very rarely] 7) either side, similar or dissimilarly arranged on the two sides of the lamina, usually inconspicuous adaxially, these and coarser often inconspicuously scalariform tertiary reticulation visible abaxially; texture thin- or thick-chartaceous, leaves rarely slightly bullate or rugulose, both surfaces with indumentum usually similar to that of stem, often sparser below or sometimes adaxial surface glabrous; petiole (0.1–)0.25–0.7(–1.3) × lamina length. Flower­clusters borne on leafless inflorescence-bearing axes, these short and ± erect to apically pendent or more often medium to long and pendulous, arising one from each axil, (5–) 10–40 cm long, axes unbranched or sometimes male or both sexes with a few long lateral branches near base or throughout length but without 2nd-order branching; both sexes often on same plant with male axes usually in lower axils or forming short lateral branches at base of mainly female inflorescence-bearing axis; clusters well-spaced or crowded; male clusters with up to c. 15 flowers, female clusters with (less than 10–)20–more than 50 crowded or rather loosely-arranged flowers; bracts triangular, up to 2 mm long; bracteoles up to 0.3(–0.5) mm long. Male flowers 4-merous, sessile, mature buds depressed-globose, c. 1 mm diam, dorsal appendages of tepals usually prominent, hairs sparse (rarely dense), adpressed or spreading. Female flowers fairly narrowly ovoid, up to 0.5 mm long; stigma rather variable, 0.6–2 mm long. Fruiting perianth 0.7–2 by 0.3–0.5(–1) mm, always with minute or longer beak, otherwise extremely varied in form, ovoid-conical or ellipsoid to obovoid ± inflated in distal part, or obtriangular in outline with truncate apex, and either scarcely laterally flattened with achene ± filling fruiting perianth, or more markedly laterally flattened with or without distinct marginal rim or narrow to broad wing and achene not filling fruiting perianth, glabrescent or more often hairy, hairs sparse to abundant, minute or coarse.

Distribution ― Tropical Africa, from Sierra Leone and Senegal to Ethiopia, south to Angola, Zimbabwe and Mozambique, Comoro Islands, Madagascar, Mascarene Islands, Pakistan, India, Sri Lanka, Bangladesh, Nepal, Bhutan, Burma, Thailand, Laos, Vietnam, southern and south-western China (including Hong Kong), Malaysia (Selangor), Indonesia (Sumatera, Kalimantan, Jawa, Nusa Tenggara [Lesser Sunda Islands], Sulawesi, Moluccas, Papua), Philippines, Papua New Guinea, Australia (Queensland, New South Wales), Solomon Islands, Vanuatu, Fiji, Tonga Islands, Samoan Islands, Society Islands, Marquesas Islands, Austral Islands.

Habitat & Ecology ― See under infraspecific taxa.

Conservation status ― See under each subspecies.

Notes ― 1. This species is much more widely-distributed geographically than any other species of Boehmeria and exhibits a wide range of variation, especially in leaf shape. However, as discussed below, it is not possible to divide this taxon into species by applying the same criteria as elsewhere in this revision. See comments by Weddell (1856: 369) extensively quoted in the introduction to this paper. We have found it necessary to widen the concept of this species even more than Weddell. Well over 30 basionyms have been proposed for the taxa which we here refer to this very variable species, for which we have tried to establish a reasonably satisfactory infraspecific classification.

2. Summary of the infraspecific classification within B. virgata

Fourteen varieties with varying degree of distinctiveness are recognised in this treatment, most of which fall clearly within one of two subspecies with centres of distribution either side of Wallace’s line, subsp. virgata to the east ( Indonesia, Australia and the Pacific) and scarcely crossing the line (c. 20 collections out of several hundred seen), subsp. macrophylla entirely to the west of it (Afro-Malagasy region, Indian subcontinent, Indochina, China, Sumatera and Jawa). The distinctions between subsp. virgata and subsp. macrophylla are summarised in Table 3.

For two reasons these two entities cannot satisfactorily be recognised as separate species. Firstly, two regional variants are intermediate in leaf morphology between the two subspecies and are here considered as best placed within subsp. virgata only because of their distribution (see following paragraph). Secondly, in the northern and western part of its distribution the most variable and frequently collected variety ( subsp. virgata var. virgata ) appears to approach subsp. macrophylla var. macrostachya via a range of forms progressively less distinct from var. macrostachya . This variation is discussed in detail below (Note 3).

Subsp. virgata comprises the widespread and variable var. virgata and three narrowly distributed regional variants; two are sympatric with var. virgata and endemic to the island of New Guinea, one closely similar to it; the other, var. maxima , is intermediate in certain leaf characters with subsp. macrophylla var. macrostachya , as is the third variety, var. austroqueenslandica (eastern Australia, allopatric to the rest of the species). Subsp. macrophylla comprises ten varieties. The variation here recognised at varietal rank is correlated with geographical distribution and some of these entities are strikingly different from one another; however, the existence of a range of intermediate forms where their distributions overlap, especially in the Himalayas, makes it impossible to recognise them at anything other than varietal rank. Molecular and classical cytological work would be very helpful in clarifying the relationships between all these entities and better interpreting this confusing variation, in the same way that cytological work on B. japonica and its allies (discussed elsewhere) has led to understanding of that hitherto equally confusing matrix of intergrading entities. The entities here formally recognised are discussed in detail in what follows. The wide range of variation still included within the two most variable varieties subsp. virgata var. virgata and subsp. macrophylla var. macrostachya also shows some correlation with geographical distribution but further regional variants cannot be formally recognised for the reasons discussed below. The pattern of variation within and between the two subspecies and their varieties is as follows.

3. The range of variation within subsp. virgata var. virgata and its approach to that of subsp. macrophylla var. macrostachya

As summarised in Table 3 the two subspecies differ in the range of variation in leaf proportions, shape and texture and characters of the marginal teeth. Subsp. macrophylla var. macrostachya is further distinguished from subsp. virgata var. virgata by its leaves always thin-textured, relatively broad (length ≤ 2(–2.25) × width), marginal teeth acute, at least 1.5 mm long, although both varieties show a wide range in number of teeth. Var. virgata is often further distinguishable from var. macrostachya by leaves often much more distinctly asymmetrical in outline and venation and sometimes with hairs on stem and upper leaf surface spreading (rather than adpressed). However, var. virgata becomes progressively less distinct in the northern and western part of its distribution ( Vanuatu, Indonesia and the Philippines), as follows.

In the Pacific var. virgata shows considerable variation between (sometimes also within) the various island groups but is mostly very distinct from var. macrostachya .

i. In Southeast Polynesia (Marquesas,Austral and Society Islands) plants are often scandent; there is an especially wide range of variation in leaf-size, texture, relative proportions, indumentum density and marginal tooth length. Most variants are distinguished from var. macrostachya by leaves relatively narrow, marginal teeth short and often blunt and adaxial (or both) surfaces often glabrous. However, certain variants (Rapa and Tahiti) have teeth up to 2 mm long and leaves broad, adpressed-hairy; these are distinguished from var. macrostachya by being always thick-textured with veins robust, upper veins rather numerous and stipules unusually large, up to 20 mm long. Plants at the extremes of this range of variation (for example leaves small narrow thin-textured and shallowly crenate as compared to large broad thick-textured and dentate) appear very different from one another, but the continuous matrix of variation (most characters varying independently of one another) makes any further formal distinction impossible.

ii. In Fiji leaves vary in size and texture but less in marginal teeth and indumentum and are distinguished from those of var. macrostachya in being shallowly-toothed (mostly crenate), mostly narrow, often asymmetrical, often glabrous; the apex of the ‘smaller’ leaves (sometimes also the ‘larger’ leaves) is unusual in being often broad-acute rather than attenuate.

iii. In the Samoan Islands leaves are even less variable, mostly small (<10 cm long), thin-textured, veins slender, teeth rather few (20–25 either side); these forms are clearly distinct from var. macrostachya in being narrow, shallowly crenate, mostly elliptic and glabrous, often markedly asymmetrical. (Only one collection has been seen with large broad leaves, 17 by 9 mm.)

iv. In Melanesia ( Vanuatu) leaves are relatively large, thin-textured, veins rather indistinct, teeth only 25–30 either side; these forms still ± conform to var. virgata in being glabrous adaxially, crenate and often asymmetrical, but are less distinct from var. macrostachya since marginal teeth are often larger, some> 1 mm long.

v. From the island of New Guinea little material has been seen; marginal teeth are mostly relatively large (as in var. macrostachya ) but otherwise leaves conform to subsp. virgata , being thick-textured with robust veins and mostly narrow, closely similar to or intermediate with the sympatric var. velutina (see below).

vi. From Sulawesi and Moluccas (i.e., towards the western limits of the distribution of var. virgata ) material is abundant with widely varying leaf-size and -texture. The majority of collections are easily distinguished from var. macrostachya , having leaves relatively narrowly elliptic-ovate, attenuate, shallowly crenate, many-toothed, ± glabrous adaxially and often thick-textured with venation ± distinct, scalariform. However, some material is less distinct, having leaves thin-textured, teeth acute,> 1 mm long, and adaxial surface abundantly adpressed-hairy.

vii. At the northern and western limits of its range, crossing Wallace’s line ( Malaysia, Sumatera, Jawa, Bali) and in the Philippines, var. virgata appears to be uncommon. Most material is somewhat intermediate with var. macrostachya in leaf texture and/or shape and size of marginal teeth. In the Philippines some material is impossible to assign to either taxon.

In summary, forms of var. virgata seen in most of the Pacific are clearly distinct from var. macrostachya , becoming less so from east to west. In Indonesia east of Wallace’s line some material is less distinct than in the Pacific, but distinction is the least clear in some of the few collections of var. virgata which cross Wallace’s line, where much material seen has most characters of var. virgata but indumentum and teeth conforming to var. macrostachya .

4. Distribution and variation in regional variants of subsp. virgata

Two regional variants are sympatric with var. virgata in the island of New Guinea.

i. Var. velutina is distinctive in its indumentum long and dense, leaves thick-textured, often distinctly subcordate, marginal teeth longer and its inflorescence-bearing axes always much-branched. It is formally recognised only at varietal level because it grades into var. virgata via a range of intermediate forms with leaves cuneate and/or more sparsely pubescent and thinner-textured.

ii. Var. maxima is distinctive in its extremely large leaves, the largest seen in this species, their size overlapping only with the largest forms of var. macrostachya . It is somewhat intermediate between the two subspecies; its marginal teeth of leaf rounded, much broader than long, and fruiting perianth with a broad thin wing surrounding a relatively small achene conform to subsp. virgata , but its thin leaves with large long teeth are closer to subsp. macrophylla . As discussed above (Note 2), it is included under subsp. virgata because of its distribution, being allopatric to subsp. macrophylla and within a small part of the distribution of subsp. virgata var. virgata .

It is distinguished from var. virgata on leaves thin-textured, both very large and relatively broad (at least some ≥ 24 cm long, longer than any seen in var. virgata ) with length mostly <1.8 × width; (in any collections of var. virgata where leaves are fairly long 15– 22 cm they will also be relatively much narrower and/or thick-textured); the number of marginal teeth is mostly more than 45 either side (mostly less than 45 in var. virgata ).

iii. Var. austroqueenslandica , allopatric to the rest of the species (eastern Australia), is distinctive in narrow attenuate leaves with marginal teeth relatively few, large, and hairs on adaxial surface and stem close-adpressed, abundant but extremely fine and inconspicuous, male inflorescence-bearing axes long, unbranched, female axes with flower-clusters often densely crowded and fruiting perianth not greatly flattened. It is somewhat intermediate in leaf characters between the two subspecies, having marginal teeth 1–2 mm long (rather than mostly <1.5 mm in subsp. virgata , mostly> 1.5 mm in subsp. macrophylla ). It is similar firstly to certain narrow-leaved Indonesian forms of var. virgata (these forms differing in teeth smaller and shorter, male axes branched), and secondly to narrow-leaved forms of the African subsp. macrophylla var. molliuscula with fruiting perianths only moderately laterally flattened (these forms differing in leaves often glabrous adaxially, teeth larger, leaf apex mostly a single long tooth and stem hairs spreading). Because of the distribution of the two subspecies with respect to Wallace’s line, this intermediate variety is also here included under subsp. virgata .

5. Distribution and variation within and between regional variants of subsp. macrophylla i. Subsp. macrophylla var. molliuscula (Afro-Malagasy) and var. macrostachya (Indian subcontinent), both frequently collected and rather variable, were hitherto considered as one taxon. Var. molliuscula is distinguishable from var. macrostachya as summarised in Table 4.

Although var. molliuscula is generally rather unlike var. macrostachya in overall appearance, those collections with the broadest leaves and the smallest teeth overlap in variation with narrow-leaved large-toothed forms of var. macrostachya , being clearly distinct only in their spreading stem indumentum. (Notably, most material from Réunion has leaves rather broad and stem hairs half-adpressed; a few collections from Bioko and Cameroon also have stem hairs half-adpressed.) However, from Tanzania most material (e.g., Harris 5095, Renvoize 1509) has more closely-adpressed stem hairs; these variants somewhat obscure the main distinction from var. macrostachya . Nevertheless, we consider the Afro-Malagasy entity worthy of formal recognition in view of its geographical separation and the fact that these variants conform to Afro-Malagasy material (rather than to var. macrostachya ) in other characters.

The density of indumentum on stem and leaves of var. molliuscula varies greatly and seems to be correlated with habitat, with almost glabrous forms in dense rainforest and much more hairy ones in open or riverine forest.

ii. These latter forms of var. molliuscula intergrade via a continuous range of intermediates with var. tomentosa which is found only in open forest and appears to be relatively uncommon and is presumed to be the dry habitat variant, occurring sporadically throughout the range of var. molliuscula . It is distinguished from var. molliuscula by indumentum on most parts of plant dense, long, pale, spreading and leaves thick-textured with robust main veins all arising in the distal half of the lamina, often rhombic-ovate and short-petioled. The material of var. tomentosa seen from Nigeria and Tanzania is the most distinctive with narrow thick leaves densely hairy adaxially. Many collections intermediate between the two varieties have been seen from Zaire, Cameroon and Angola (a few also from Nigeria, Uganda and Zambia), mostly from more moist habitat, with markedly thick-textured narrow leaves but indumentum (especially on leaves) much sparser.

iii. Var. macrostachya is widespread and apparently common in the northern and central part of the Indian subcontinent, with a few collections also seen from the southern part of peninsular India and Sri Lanka. (According to Chen et al. (2003) it also occurs in China , but all collections seen hitherto identified as this entity were intermediate with var. rotundifolia, var. scabrella or var. strigosa . It is characterised by stem hairs closely-adpressed and a combination of other characters as listed in Table 4, but leaf shape and indumentum of abaxial leaf surface are extremely variable. Most collections from the eastern and western Himalayas and all from central India have relatively wide leaves (length 1.25–1.5(–1.75) × width), with marginal teeth numerous, (30–)40–50(–60) and often small, 1.5–2 by 4–5 mm. In the eastern Himalayas some material has relatively narrower elliptic-ovate leaves with fewer larger teeth more similar to var. molliuscula .

iv. Many collections of subsp. macrophylla have been seen from the Indian subcontinent; many of these, especially from the Himalayas (including the type of B. massuriensis ) exhibit a range of intergrading forms intermediate between the various entities whose different distributions overlap in that region (var. canescens, var. macrostachya, var. minuticymosa , var. rotundifolia and var. scabrella ). Most of these have some leaf characters of var. scabrella (marginal teeth numerous and relatively narrow, leaves often asymmetrical in outline, often thick-textured with hairs conspicuous rather stiff, or asymmetrically cordate with sparse hairs; see Note x below) but inflorescence-bearing axes pendulous as in var. macrostachya . Some of these forms also have minute peduncles in the flower-clusters as in var. minuticymosa . From mainland China and Vietnam relatively few collections of the subspecies as a whole have been seen; five varieties are known (see Notes viii–x, xii, xiii below) and some material is intermediate between them.

v. Three varieties are sympatric to var. macrostachya but restricted to small parts of its distribution, two others partly sympatric but more widespread and four others allopatric.

vi. Var. longissima (Tamil Nadu and Sri Lanka) is restricted to high altitude evergreen rainforest; it is more similar in its narrow leaves with relatively few teeth to the Afro-Malagasy var. molliuscula (also restricted to moist forest) than to the Indian var. macrostachya which occurs in a wide range of habitats. It is distinctive in its spreading but minute straight stem hairs, its fruiting perianth densely minutelyred-pubescent, broad, scarcely flattened and its leaves often rhombic-ovate. Although it is restricted to a small part of the range of var. macrostachya and no collections intermediate in stem indumentum or fruit form have been seen, the distinctive characters are so slight that we see no reason to raise it to higher rank.

vii. Var. canescens (eastern Himalayas, sympatric within part of the distribution of var. macrostachya, var. minuticymosa and var. scabrella ), is similar to var. minuticymosa (see Note ix), in its marginal teeth numerous, relatively narrow and flower-clusters elongate rather than ± globose with female flowers pedicellate often pedunculate. However, it differs markedly from that and all other varieties in its inflorescence-bearing axes extremely slender (only half of the diameter of other varieties) with clusters sparse, widely spaced and very few-flowered, its female perianth extremely small in both flower and fruit and its stem indumentum of two kinds, dense fine closely-adpressed hairs which at the stem apex and at upper nodes are completely concealed by dense coarser spreading much longer hairs. Hairs on the abaxial leaf surface are soft and of varying lengths, usually much more abundant than in other varieties of subsp. macrophylla , often giving the distinctive whitish cast to the leaf indicated by its name. Some material from the eastern Himalayas of var. minuticymosa and var. rotundifolia (see Notes viii, ix) with a few long spreading hairs near the stem apex in addition to their shorter adpressed hairs tends somewhat towards this taxon.

viii. Var. rotundifolia (eastern Himalayas, south-western China) also has marginal teeth relatively narrow, but fewer than in var. canescens and is distinctive in its terminal tooth of the leaf apex abrupt, very narrow, long and ± tail-like and its marginal teeth strongly up-curved, distal ones markedly more in-curved than proximal ones. Stem indumentum is abundant, short and adpressed, but longer hairs which are sparse, coarser and spreading (as in var. canescens but much more sparse) are sometimes also present; collections have also been seen ± intermediate in leaf-shape with var. canescens with leaf-acumen abrupt but short and inflorescence-bearing axes rather slender. Forms somewhat intermediate with var. macrostachya or var. scabrella have been seen from the eastern Himalayas and southern China with leaves much narrower and less abruptly acuminate but with distal teeth markedly up-curved. From Sikkim and Burma other forms of more obscure identity have been seen less abruptly acuminate and with hairs on leaves on stems conspicuous, coarse and spreading but with leaves broad and sometimes two kinds of hair near the stem apex. From Vietnam similar intermediate forms, but with soft rather than coarse spreading hairs, have been seen.

ix. Var. minuticymosa is the only variety seen from Thailand and extends eastwards to Indochina and South China and westward to the Himalayas where it is sympatric to var. macrostachya . It is especially distinctive in its often elongate female clusters with many minute flattened peduncles bearing several pedicellate flowers (otherwise seen only in var. canescens ); it is also characterised by leaves medium-sized with base cuneate to rounded, thin-textured and often slightly bullate like those of var. macrostachya but more uniform in size and narrower with marginal teeth numerous (40–45 either side) and rather small as in var. canescens , while hairs on adaxial surface are conspicuous, usually coarse and rough and female inflorescence-bearing axes rather short (c. 13 cm) and often erect with clusters often crowded as in var. scabrella ; fruiting perianths are distinctive, broadly ovoid with rounded base, pale yellowish brown (rather than darker reddish brown), glabrous except at apex. Yahara (1981: 21) included this taxon within ‘ B. platyphylla’ ( = var. macrostachya ) but noted that its leaves were more uniform than in material from elsewhere and its inflorescence-bearing axes often bisexual (males on short branches near the base of the axis).

In the Himalayas and further south in C. India a range of variants intermediate between var. minuticymosa and var. macrostachya also occurs, with female flowers clearly pedunculate and/or pedicellate but fruiting perianths narrow, tapering, sometimes much more hairy and leaves broader or cordate. A few collections from the Himalayas are somewhat intermediate with var. canescens in stem indumentum, leaf shape and inflorescence architecture.

x. Var. scabrella is sympatric to var. macrostachya in the Indian subcontinent but more widespread, occurring from the Himalayas (most material seen being from there) to south-western and southern China (incl. Hong Kong), and in Indonesia west of Wallace’s line in Jawa, Bali and south-eastern Borneo. It is often very similar to var. rotundifolia in marginal teeth numerous, markedly up-curved and inflorescence-bearing axes short, erect, much-branched, the male axes often with short branches throughout length, but is distinctive within subsp. macrophylla in its leaves rough-hairy (abaxial hairs spreading), relatively small, broad, mostly asymmetrical, often thick-textured and bullate; marginal teeth small; leaf apex with short, broad, rather gradual acumen toothed in its basal third and inflorescence-bearing axes with clusters often congested. It has a slightly lower altitudinal range than var. rotundifolia and occurs in forest and thickets. Var. scabrella is sympatric with subsp. virgata var. virgata where the latter crosses Wallace’s line in Jawa and Bali but the two entities are morphologically very distinct with no intermediate forms nor possibility of confusion, since subsp. virgata has inflorescence-bearing axes long, pendulous and usually also leaves narrow, smooth shallowly crenate, adpressed-hairy abaxially. Forms of ssp. virgata with leaves slightly less dissimilar vegetatively (spreading-hairy abaxially, teeth comparatively long) have been seen (restricted to the island of New Guinea), but have a very different overall appearance, leaves symmetrically broadly subcordate to truncate with marginal teeth relatively much broader (usually ≥ 4 mm wide). From various parts of the Indian subcontinent abundant material has been seen intermediate between var. scabrella and var. macrostachya , and from the Himalayas material intermediate with var. rotundifolia in leaf shape. In Jawa some collections approach the allopatric but neighbouring var. sumatrana in leaf-size and shape but var. scabrella differs from that variety in hairs on abaxial surface spreading, on stem and adaxial surface often half-adpressed, indumentum often dense, rather than all indumentum close-adpressed and very sparse.

xi. Var. sumatrana and the remaining two varieties, var. densiglomerata and var. strigosa , form a distinctive small group with leaves ± symmetrical broad ± membranous, base truncate to cordate, marginal teeth few and hairs fine and adpressed. Var. sumatrana is allopatric to the rest of the subspecies (Sumatera) and is distinguished from both var. strigosa and var. densiglomerata by inflorescence-bearing axis rather short, erect, bisexual, often branched and leaves extremely sparsely hairy, distal marginal teeth markedly more up-curved than proximal ones; distinct additionally from var. densiglomerata by female clusters not densely congested and from var. strigosa by leaves small and stipules rather long. No intermediate forms have been seen. In addition to the characters of leaf shape and marginal teeth, var. sumatrana is easily distinguished from var. macrostachya by its petiole long relative to lamina length and its inflorescence-bearing axes short and erect. In general appearance it is somewhat similar to certain fairly symmetrical-leaved thin-leaved forms of var. scabrella (allopatric but neighbouring), but these differ in leaf indumentum coarse and spreading.

xii. Var. densiglomerata , known only from rather scanty material from southern and central China, has small leaves like those of var. sumatrana but usually less sparsely hairy and inflorescence-bearing axes unisexual, the females very different from both var. sumatrana and var. strigosa , very short (less than 5 cm), unbranched and flower-clusters so tightly congested that individual flower-clusters are indistinguishable; male and bisexual axes are similar to the branched (bisexual) axes of var. sumatrana and leaves differ from it only in indumentum less sparse and marginal teeth mostly fewer (10–13), less up-curved.

xiii. Var. strigosa , sympatric to var. densiglomerata in southern China but extending to Vietnam, is distinguished from both var. sumatrana and var. densiglomerata in its indumentum of leaf underside conspicuously dense and shining silky,leaves mostly larger, marginal teeth more numerous and usually smaller and narrower, female inflorescence-bearing axes long, pendulous, unbranched (as in var. macrostachya ). It differs additionally from var. sumatrana in axes never bisexual and from var. densiglomerata in female clusters well-spaced.A few collections seen from Vietnam are somewhat intermediate with var. densiglomerata (not recorded from Vietnam) in having small leaves and fewer (only 16) teeth although the silky hairs are fairly dense. A few collections have been seen somewhat intermediate with var. macrostachya , with leaves broad ± cordate membranous but indumentum on abaxial surface soft and spreading.

xiv. Several varieties can be confused with other species. This is discussed under the subspecies as a whole.

Key to subspecies and varieties of B. virgata

1. Leaves symmetrical, truncate to cordate,lamina broad (length only 1–1.2(–1.8) × width, thin-textured with hairs both sides, these fine, closely-adpressed, sometimes dense and silky abaxially, marginal teeth only 13–25(–30) either side; petiole usually ≥ 0.6 × lamina length; stem hairs straight, closely-adpressed. — Indochina; southern and central China; Indonesia – Sumatera ........................... 2

1. Leaves without above combination of characters: either narrowly rounded to cuneate at base and relatively narrower, or if broad and truncate to cordate then hairs, at least abaxially, coarse, spreading, rough and/or texture thick and/or lamina markedly asymmetrical; marginal teeth usually 35–60 either side; petiole usually less than half lamina length (stem hairs adpressed or spreading)......................... 4

2. Hairs on abaxial surface of leaf dense, ± obscuring surface and lying in a regular pattern giving conspicuously shiny-silky appearance, marginal teeth (16–)20–30 either side; female inflorescence-bearing axes pendulous, 10–40 cm long. — Southern China; Vietnam..................................... o. subsp. macrophylla var. strigosa

2. Hairs on both sides of leaf sparse, leaves not shiny-silky abaxially, marginal teeth 10–17 either side; female inflorescence-bearing axes erect, 1.5–12 cm long........... 3

3. Inflorescence-bearing axes mostly unisexual, the female ones only 1.5–4.5 cm long, unbranched, densely congested with individual clusters usually indistinguishable; male and bisexual axes mostly <5 cm; fruiting perianth broadly obconical, inflated at apex; leaves with up to 13 teeth either side. — Southern China...................................... n. subsp. macrophylla var. densiglomerata

3. Inflorescence-bearing axes mostly bisexual and branched but if female, and also unbranched, then 8–12 cm long; individual female clusters contiguous or not, but distinguishable; fruiting perianth conical or obovoid, somewhat laterally flattened; leaves with more than 13 teeth either side. — Indonesia – Sumatera .. m. subsp. macrophylla var. sumatrana

4. Leaf apex abruptly acuminate, a single tooth, (5–) 15–20 mm long, very narrow and ± linear ‘tail-like’, c. 2 mm wide for most of its length, with 1–2 pairs of often markedly in-curved lateral teeth at its base; marginal teeth acute and markedly up-curved, distal ones increasingly in-curved, 2 –5 mm long and relatively narrow with width rarely> 1.25 × length; leaves sparsely hairy adaxially; stem with adpressed hairs (rarely also long spreading hairs near apex). — Eastern Himalayas; south-western China....................................... j. subsp. macrophylla var. rotundifolia

4. Leaf apex gradually attenuate or if an abrupt acumen then not linear tail-like and basal third of acumen toothed; (marginal teeth often shorter and broader, often only slightly up-curved, leaf sparsely or densely hairy; stem hairs adpressed or spreading or both).................... 5

5. Female flowers with minute flattened pedicels, often in small groups on minute branched peduncles........ 6

5. Female flowers sessile......................... 9

6. Stem with both spreading and adpressed indumentum 7

6. Stem with only adpressed indumentum, hairs all of similar nature and mostly ± same length................. 8

7. Stem with abundant short hairs (0.2–0.4 mm long), which are fine, closely-adpressed and clearly visible lower on stem but at apex and upper nodes concealed by much long- er hairs (c. 1 mm) which are coarser, dense and spreading; leaves abaxially with sparse hairs of varying length, soft, fine and often giving a whitish cast; inflorescence-bearing axes very slender, ≤ 0.2 mm diam, pendulous with small well-spaced clusters; fruiting perianth small and narrow, ≤ 0.5 by 0.3 mm, apex ± beak-like. — Eastern Himalayas............ i. subsp. macrophylla var. canescens

7. Stem with all hairs of similar texture and length, c. 0.5–0.7 mm long, the abundant adpressed hairs not concealed by the sparse spreading hairs present at apex; leaves not whitish abaxially; inflorescence-bearing axes robust (0.4–) 0.6–1 mm diam, ± erect, with crowded clusters; fruiting perianth broadly ovoid, 0.7–1.2 by 0.5–0.8 mm, without beak. — Himalayas to Indochina......................... k. subsp. macrophylla var. minuticymosa

8. Leaves cuneate, thin-textured; fruiting perianth broadly ovoid without beak. — Himalayas to Indochina..................... k. subsp. macrophylla var. minuticymosa

8. Leaves cordate at base, often thick-textured; fruiting perianth often narrowly spindle-shaped............................. subsp. macrophylla intermediate between............ var. macrostachya and var. minuticymosa

9. Stem with two distinct kinds of indumentum, long spreading hairs (c. 1 mm) which are dense at stem apex and nodes where they conceal abundant shorter (0.2–0.4 mm) closely-adpressed hairs clearly visible lower on stem; inflorescence-bearing axes very slender, ≤ 0.2 mm diam, pendulous with small well-spaced clusters; fruiting perianth small and narrow, ≤ 0.5 by 0.3 mm; leaves abaxially with rather sparse soft fine hairs of varying lengths often giving whitish cast, adaxially with long soft curved hairs. — Eastern Himalayas... i. subsp. macrophylla var. canescens

9. Stem with either spreading or adpressed indumentum, hairs all of similar nature and mostly ± same length; inflorescence-bearing axes robust, (0.4–) 0.6–1 mm diam; fruiting perianth usually> 0.7 by 0.5 mm; (axes sometimes erect, clusters sometimes contiguous; leaves densely or sparsely hairy, if whitish abaxially then hairs ± uniform, mostly> 0.5 mm long)......................... 10

10. Leaves (both sides) and stems with hairs spreading, dense, ± obscuring surface; leaves thick-textured......... 11

10. Leaves and stems with hairs either closely-adpressed (dense or sparse) or spreading but sparse (leaves thin or thick-textured)............................... 12

11. Inflorescence-bearing axes unbranched or (male) few-branched near base, pendulous; fruiting perianth with marginal rim, achene ± filling fruiting perianth; hairs on stem and leaves beneath 0.5–1 mm long, often pale giving whitish sheen to whole plant especially leaves abaxially; leaf base broadly cuneate to rounded or narrowly subcordate; low subshrub, ≤ 1.5 m tall. — Afro-Malagasy......................... f. subsp. macrophylla var. tomentosa

11. Inflorescence-bearing axes much-branched, male axes sometimes ± erect; fruiting perianth with distinct relatively broad marginal wing either side comprising 0.5–0.7 × total fruiting perianth width; hairs on stem and leaves beneath shorter and velvety, ≤ 0.2 mm, brownish; leaf base broadly subcordate to truncate; large shrub or tree, 1.5–2.5 m tall. — Indonesian Papua; Papua New Guinea................................. b. subsp. virgata var. velutina

12. Leaves very large and broad, at least some on plant 24–35 by (11–) 15–20 cm, thin-textured, length only up to 1.75(–2) × width; marginal teeth 40–60 either side, large (1.5–3 mm long); hairs both sides fine and inconspicuous, adpressed adaxially, spreading abaxially; stem hairs half-adpressed.................................. 13

12. Leaves much shorter or if up to 20(–22) cm long then much narrower and/or number of marginal teeth up to 35 either side (leaves thin or thick-textured, hairs on leaves and stem adpressed or spreading, marginal teeth long or short)...................................... 14

13. Marginal teeth broad-acute, 1.5–2 by (2–) 4–7 mm, width (1.3–)2.5–3.5 × length. — Indian subcontinent.................... g. subsp. macrophylla var. macrostachya

13. Marginal teeth rounded, 1.5–3 by (5–) 8–12 mm, width 4–5 × length. — Indonesian Papua ....................................... c. subsp. virgata var. maxima

14. Marginal teeth of leaves indistinct or up to 1 mm long (or if ≥ 1 mm long then rounded) and with width usually ≥ 4 × length; leaf length ≥ 1.8 × width; leaves glabrescent or with inconspicuous adpressed hairs adaxially, basal veins extending well into distal half and on one side often almost to tip, upper lateral veins all arising in distal half. — Indonesia; Pacific................ a. subsp. virgata var. virgata

14. Marginal teeth of leaves acute, mostly ≥ 1.5 mm long and relatively narrower; leaves often much broader and/or with spreading hairs (basal veins extending less far or not, lowermost upper vein often arising below middle of lamina)........................................... 15

15. Inflorescence-bearing axes erect, only 5–10 cm long, male axes with lateral branches throughout length; leaves at least slightly asymmetrical with outline of two sides of lamina often dissimilar and base often oblique, often ± bullate and coarsely rough-hairy adaxially, usually <10(–13) cm long. — Eastern Himalayas to southern China; Indonesia – Jawa, Borneo.... l. subsp. macrophylla var. scabrella

15. Inflorescence-bearing axes pendulous, 10–40 cm long, branched at base or unbranched; leaves not or scarcely asymmetrical, ≥ 10 cm long (bullate or not, hairs often fine, soft and inconspicuous)........................ 16

16. Stem hairs spreading, marginal teeth 2–5 mm long, only 15–35 either side, lamina length (1.5–)2–3.5 × width; inflorescence-bearing axes always unbranched, clusters spaced 2 –10 mm apart........................ 17

16. Stem hairs closely-adpressed; marginal teeth 1.5–2 mm long (teeth often more than 35 either side; lamina length often less than 2 × width; male inflorescence-bearing axes sometimes with several long branches near base, clusters sometimes contiguous)........................ 19

17. Fruiting perianth with broad distinct wing either side comprising 0.5–0.7 × total fruiting perianth width; stipules 15– 20 mm long............ a. subsp. virgata var. virgata (Southeast Polynesian form, see under var. virgata , Note 5)

17. Fruiting perianth with only a marginal rim or at most a narrow indistinct wing; stipules ≤ 10 mm ............. 18

18. Stem hairs fine and straight but very short, 0.1–0.2(–0.3) mm long; fruiting perianth densely-pubescent throughout with minute reddish hairs (<0.1 mm long) and broadly ovoid, ≤ 1.5 mm long with distinct beak up to 0.3 × whole length, not or scarcely laterally flattened with slight marginal rim; seed ± filling perianth. — South India; Sri Lanka.................. h. subsp. macrophylla var. longissima

18. Stem hairs, at least some,> 0.4 mm long, often curved; fruiting perianth without distinct beak, often obovoid, distinctly laterally flattened and often ± winged with hairs usually longer, often pale and restricted to apex. — Afro-Malagasy............... e. subsp. macrophylla var. molliuscula

19. Leaves thick-textured,often glabrescent adaxially with robust veins and large stipules 15–20 mm long; fruiting perianth with broad thin-textured wing comprising 0.5–0.7 × total fruiting perianth width; stipules 15–20 mm long............................. a. subsp. virgata var. virgata (Southeast Polynesian form, see under var. virgata , Note 5)

19. Leaves thin-textured with fine adpressed hairs adaxially and slender veins; stipules ≤ 10 mm long (fruiting perianth with or without wing).......................... 20

20. Marginal teeth (22–) 35–60 in number, lamina relatively broad with length 1.5–2(–2.25) × width; fruiting perianth often much-flattened and distinctly winged. — Indian subcontinent.... g. subsp. macrophylla var. macrostachya

Figures

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

Map 24 Distribution of Boehmeria virgata (G.Forst.) Guillem.subsp.macro­ phylla (Hornem.) Friis & Wilmot-Dear var.molliuscula Blume) Friis & Wilmot- Dear () and B. virgata (G.Forst.) Guillem. subsp. macrophylla (Hornem.) Friis & Wilmot-Dear var. tomentosa (Wedd.) Friis & Wilmot-Dear (●).

Map 25 Distribution of Boehmeria virgata (G.Forst.) Guillem.subsp.macrophylla (Hornem.) Friis & Wilmot-Dear var. macrostachya (Wight) Friis & Wilmot-Dear (●) and B. virgata (G.Forst.) Guillem.subsp.macrophylla (Hor- nem.) Friis & Wilmot-Dear var.longissima (Hook.f.) Friis & Wilmot-Dear (ä).

Map 26 Distribution of Boehmeria virgata (G.Forst.) Guillem. subsp. macrophylla (Hornem.) Friis & Wilmot-Dear var. canes­ cens (Wedd.) Friis & Wilmot-Dear.

Map 27 Distribution of Boehmeria virgata (G.Forst.) Guillem. subsp.macrophylla (Hornem.) Friis & Wilmot-Dear var.rotundifolia (D.Don) Friis & Wilmot-Dear (●) and intermediates between B. vir­ gata subsp.macrophylla var. rotundifolia and other varieties (ä).

Map 28 Distribution of Boehmeria virgata (G.Forst.) Guillem. subsp. macrophylla (Hornem.) Friis & Wilmot-Dear var. minuticy­ mosa Acharya,Friis & Wilmot-Dear (●) and intermediates between B. virgata (G.Forst.) Guillem.subsp.macrophylla var.minuticymosa and other varieties (ä).

Map 29 Distribution of Boehmeria virgata (G.Forst.) Guillem.subsp.macro­ phylla (Hornem.) Friis & Wilmot-Dear var.scaberrima (Roxb.) Friis & Wilmot- Dear (●), B. virgata (G.Forst.) Guillem. subsp.macrophylla (Hornem.) Friis & Wilmot-Dear var.sumatrana (Miq.) Friis & Wilmot-Dear (▲) and intermediates between B. virgata subsp. macrophylla var.scaberrima and B. virgata subsp. macrophylla var. macrostachya (ä).

Map 30 Distribution of Boehmeria virgata (G.Forst.) Guillem. subsp. macrophylla (Hornem.) Friis & Wilmot-Dear var. densiglomerata (W.T.Wang) Friis & Wilmot-Dear (Ê), B. virgata (G.Forst.) Guillem. subsp. macrophylla (Hornem.) Friis & Wilmot-Dear var. strigosa (W.T.Wang) Friis & Wilmot-Dear (●), interme- diates between B. virgata subsp. macrophylla var. densiglomerata and B. virgata subsp. macrophylla var. strigosa (ä) and intermediates between B. virgata subsp. macrophylla var. strigosa and other varieties (✱ under ● representing var. strigosa).

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.

Fig. 22 a–e: Boehmeria virgata subsp. virgata var. velutina Friis & Wilmot-Dear. a. Habit of stem with inflorescence-bearing axes; b. leaf, detail of margin and adaxial surface; c. leaf, detail of abaxial surface; d. detail of stem and stipule; e. fruiting perianth. — f–i: Boehmeria virgata subsp. virgata var. maxima Friis & Wilmot-Dear. f. Habit of stem with inflorescence-bearing axes; g. leaf; h. leaf, detail of adaxial surface; i. fruiting perianth (a–e: Davis 596; f, h, i; Mahyar 436; g: Van Royen 7542; all K). — Scale bars: a, g = 2 cm; b-d, h = 2 mm; e, i = 1 mm; f = 10 cm.

Fig. 23 a–c: Boehmeria virgata subsp. virgata var. austroqueenslandica (Domin) Friis & Wilmot-Dear. a. Leaf; b. detail of stem and stipules; c. fruiting perianth. — d–h: Boehmeria virgata subsp. macrophylla var. molliuscula (Blume) Friis & Wilmot-Dear. d. Leaf; e. leaf, detail of adaxial surface; f. leaf, detail of abaxial surface; g. detail of stem and stipules; h. fruiting perianth. — i–l: Boehmeria virgata subsp. macrophylla var. tomentosa (Wedd.) Friis & Wilmot-Dear. i. Leaf; j. leaf,detail of abaxial surface;k. detail of stem and stipules; l. fruiting perianth.— m–o: Boehmeria virgata subsp. macrophylla var. longissima (Hook.f.) Friis & Wilmot-Dear.m. Habit of stem with inflorescence-bearing axes; n. detail of stem and stipules;o. fruiting perianth (a–c: Melville & Hunt 3628; d–h: Manning 2007; i, j: McClintock 147; k, l: Daramola 67450; m, o: Gamble 1260B; n: Bourne s.n.; all K). — Scale bars: a, d, i, m = 2 cm; b, e-g, j, k, n = 2 mm; c, h, l, o = 1 mm.

Fig. 24 a–i: Boehmeria virgata subsp. macrophylla var. macrostachya (Wight) Friis & Wilmot-Dear. a. Habit of stem with inflorescence-bearing axes; b. leaf, detail of adaxial surface;c. leaf, detail of abaxial surface;d. detail of stem and stipules;e. detail of male inflorescence-bearing axis and flower-clusters (inflorescences); f. male bud; g. detail of female inflorescence-bearing axis and flower-cluster (inflorescence); h, i. fruiting perianths of different form (from different plants). — j–o: Boehmeria virgata subsp. macrophylla var. scabrella (Roxb.) Friis & Wilmot-Dear. j. Habit of stem with branched inflorescence-bearing axes; k. leaf; l. leaf,detail of adaxial surface; m. leaf, detail of abaxial surface;n. detail of stem and stipules; o. fruiting perianth. — p: Boehmeria virgata subsp. macrophylla var. canescens (Wedd.) Friis & Wilmot-Dear. Leaf, detail of adaxial surface (a–c, h: Gamble 9034; d, i: Haines 5068; e, f: Haines 2309; g: Clarke 34129; j: Schiffner 1900; k, n: Hooker & Thompson s.n.; l, m, o: Ford 173; p: Wallich 4582; all K). — Scale bars: a, j, k = 2 cm; b-d, l-n = 2 mm; e-h, i, o = 1 mm.

Fig. 25 Boehmeria virgata subsp. macrophylla var. canescens (Wedd.) Friis & Wilmot-Dear. a. Habit of stem with inflorescence-bearing axes; b. leaf, detail of adaxial surface; c. leaf, detail of abaxial surface; d. detail of stem and stipules; e. detail of male inflorescence-bearing axis with flower-clusters (inflorescences) and bracts; f. male bud; g. detail of female inflorescence-bearing axis with flower-cluster and bract; h. pedicellate fruiting perianth (a, d, g, h: Kanai 6307148, BM; b, c: Wallich 4582, K; e, f: Wallich 4582D, K). — Scale bars: a = 2 cm; b–d = 2 mm; e-h = 1 mm.

Fig. 26 Boehmeria virgata subsp. macrophylla var. rotundifolia (D.Don) Friis & Wilmot-Dear. a. Habit of stem with inflorescence-bearing axes; b. detail of stem with branched male inflorescence-bearing axes; c–e. leaves from different plants; f. leaf, detail of adaxial surface; g, h. leaf, detail of abaxial surface; i. detail of stem and stipules; j. detail of female inflorescence-bearing axis with flower-clusters (inflorescences) and bracts; k. fruiting perianth (a, h: Hooker s.n., K; b, e-g, i: Stainton 1622, BM; c, j, k: Kanai 6307118, BM; d: Nicholson 2359, BM). — Scale bars: a–e = 2 cm; f-j= 2 mm; k = 1 mm.

Fig. 27 Boehmeria virgata subsp. macrophylla var. minuticymosa (Acharya & Yonek.) Friis & Wilmot-Dear. a. Habit of stem with female inflorescence-bearing axes; b. leaf, detail of adaxial surface; c. leaf, detail of abaxial surface; d. detail of stem and stipules; e. detail of branched male inflorescence-bearing axes with flower-clusters (inflorescences); f. male bud; g. detail of female inflorescence-bearing axis with one flower-cluster (inflorescence), flowers pedicellate; h. detail of part of fruiting cluster, showing fruiting perianths arising from common peduncle; i. fruiting perianth (a-d, g-i: Chantaranothai et al. 90/452; e, f: Chantaranothai et al. 90/68; all K). — Scale bars: a = 2 cm; b = 5 mm; c-e, g = 2 mm; f, h, i = 1 mm.

Fig. 28 a–e: Boehmeria virgata subsp. macrophylla var. sumatrana (Miq.) Friis & Wilmot-Dear. a. Habit of stem with branched bisexual inflorescence-bearing axes with flower-clusters (inflorescences); b. detail of stem with unbranched female inflorescence-bearing axis; c. leaf, detail of abaxial surface;d. detail of stem and stipules; e. detail of lower part of branched bisexual inflorescence-bearing axes. — f–l: Boehmeria virgata subsp. macrophylla var. strigosa (W.T.Wang) Friis & Wilmot-Dear. f. Habit of stem with branched bisexual inflorescence-bearing axes with flower-clusters (inflorescences); g, h. leaves from different plants; i. leaf, detail of abaxial surface; j. detail of stem and stipules; k, l. fruiting perianths (from different plants) (a, c-e: Praet s.n., L; b: Bunnemeijer 4828, L; f, j, k: Chow & Wai 79126, E; g, l: Balansa 595, K; h, i: Cuong 150, L). — Scale bars: a, b, g, h = 2 cm; c–e, i, j = 2 mm; f = 10 cm; k, l = 1 mm.

Fig. 29 Boehmeria virgata subsp. macrophylla var. densiglomerata (W.T.Wang) Friis & Wilmot-Dear. a. Habit of stem with inflorescence-bearing axes; b. leaf, detail of adaxial surface; c. leaf, detail of abaxial surface; d. detail of stem and stipules; e. portion of female inflorescence-bearing axis showing ex- tremely congested flower-clusters (inflorescences); f, g. fruiting perianths of different form (from same plant) (all: Luo 0132, K). — Scale bars: a = 2 cm; b, c = 5 mm; d = 2 mm; e–g = 1 mm.