Boehmeria listeri Friis & Wilmot-Dear

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 : 203-205

33. Boehmeria listeri Friis & Wilmot-Dear — Fig. 39 ; Map 42

Boehmeria listeri Friis & Wilmot-Dear in Wilmot-Dear et al. (2010) 432. ― Type: Lister 99 (holo CAL; iso K), India, Duphla Hills, Harpili [Hapoli], 19 Dec . 1874.

Tree or shrub, 2–3 m tall, or rarely subshrub, <1 m tall; young stems up to 2 mm diam with hairs of usually two kinds, some abundant and relatively long (0.2–0.3 mm), curved ± adpress- ed) usually mixed with sparse minute (<0.1 mm long) spreading hairs; later glabrescent. Stipules narrowly triangular, conspicuous 9–11 by c. 2.5 mm, with long hairs (c. 0.5 mm long) on midrib and minute but abundant pubescence elsewhere. Leaves opposite, slightly or more often markedly dimorphic with length of ‘larger’ 1.25–2.5 × length of ‘smaller’ ones and relatively broader with more distinctly acuminate apex; slightly asymmetrical (outline of two sides slightly dissimilar), narrowly elliptic-ovate to elliptic, 10–21 by 3.5–7.5 cm, length (2.3–)2.8–3.1 × width; margin finely-serrate, teeth (40–)45–65 either side, up-curved, acute, minute 0.5–1(–1.5) by 1–3(–4) mm with width 1–2(–3) × length; leaf apex attenuate-acuminate often slightly sideways-curved, base asymmetrically rounded or slightly cuneate; basal veins extending into distal third on one side, just in distal half on other side, upper lateral veins usually dissimilar, on narrow side only 3, all arising in distal half, on other side usually an additional (1–)2 arising near or below middle of lamina, all veins inconspicuous adaxially, finely prominent abaxially, coarser tertiary veins also finely prominent; texture very thin-chartaceous, leaves drying grey-green or blackish; adaxial surface with a minute bullation in centre of each areole, with single hair arising from it, otherwise glabrous, abaxial surface with two kinds of hairs like the stem, the minute ones throughout leaf surface, often giving a pale sheen, the long ones longer than on the stem (0.5–1 mm), sparse and restricted to the venation; petiole variable, 0.2–0.3 × lamina length, 2– 5 cm, with two kinds of hairs like the abaxial leaf surface. Flower­clusters arranged along leafless inflorescence-bearing axes, these ± pendulous, 1–2 per axil, unbranched or with 1– 2 long lateral branches very close to base, appearing as if several from each axil, 5 –13 cm long, with long hairs and often also minute ones like the stem; both sexes often on same axes, mostly in unisexual clusters with male clusters in lower part, female distally, but sometimes clusters mostly bisexual and rarely also a few male flowers present in mainly female clusters at extreme apex distal to entirely female clusters; bracts broadly triangular, often conspicuous (especially when clusters are few-flowered), up to 1 by 1 mm; clusters spaced 1–10 cm apart or sometimes ± contiguous; male clusters 2–4 mm diam, with few–10(–15) flowers, female clusters 2–3 mm diam, with (10–)20–more than 40 crowded flowers; bracteoles triangular, inconspicuous, less than 0.3 mm long. Male flowers 4-merous, sessile, mature buds globose, c. 1.5 mm diam, tepals with apiculus and prominent dorsal appendages and abundant long hairs like the stem. Female flowers obovoid (rarely ovoid) with indistinct beak, with dense long hairs like the stem; stigma variable 1–2(–2.5) mm long. Fruiting perianth obovoid to broadly obconical often broadly truncate at apex or sometimes with minute beak, 1–1.3 by 0.5–1 mm, slightly laterally flattened or indistinctly several-angled but without marginal rim or wing, abundantly long-hairy. Achene almost filling fruiting perianth.

Distribution ― Eastern Himalaya: India, Bhutan, Bangladesh, Burma.

Habitat & Ecology ― Forest understory in partial shade; slopes of subtropical forest, river margins, on limestone; 150– 1000 m altitude.

Conservation status ― Near Threatened (NT). The conservation status was estimated by Wilmot-Dear et al. (2010: 435), with an EOO of 97 408 km 2. The species occurs in areas of low habitat disturbance, while a few localities were close to areas of intensive agriculture. However, due to the relatively wide geographical and ecological range of the species it was decided not to place the species in a threat category.

Notes ― 1. Boehmeria listeri is rather nondescript in appearance, resembling various different species in various characters, such that its best placing in the genus is unclear. Its diagnostic characters are its leaves long narrow and grey-green (drying greyish brown), often elliptic (rather than ovate which is much more common in the genus) with teeth numerous and small, venation rather asymmetrically arranged, its indumentum of mixed long and minute fine hairs usually present on most parts of the plant, the minute ones giving a slightly greyish appearance and its fruiting perianth unwinged, short, broad, usually obconical. It is provisionally placed here since B. pilosiuscula (sympatric in India and Burma) has a similarly obconical fruiting perianth (although usually ± flattened at its apex), asymmetrical leaves (but shorter relatively broader with fewer longer teeth) and two clearly different kinds of indumentum on many parts, differing in the fine pubescence being less minute and more sparse on leaves, petioles and stipules, which are not distinctly greyish. Flowers are also differently arranged on the bisexual axes in B. pilosiuscula , male clusters being few, restricted to the apex (rather than numerous, mostly in the lower half of the axis) and bisexual clusters are few with only a few male flowers; in B. pilosiuscula female and bisexual inflorescence-bearing axes are always single and unbranched, usually shorter, ± erect and often very congested. However, molecular work is needed to clarify its position.

2. On his original label King apparently considered B. listeri to be a variety of the sympatric but more widespread B. penduliflora ( B. macrophylla D.Don ). That species has leaves somewhat similar-textured with hairs of two lengths on the abaxial surface but leaves are much narrower and often much longer (length 5–7 × width), glabrous adaxially (except the young leaves at the extreme apex of the stem), its stem hairs are uniform and its fruiting perianth has a distinct broad wing. We have seen one specimen, one of two K duplicates of Griffith 4555 somewhat intermediate between the two, species with stem indumentum uniform and perianth flattened-obovoid fruiting with a distinct marginal rim as in B. penduliflora but with leaf shape and proportions as in B. listeri . This specimen appears to be part of a mixed collection since the second K sheet and several other duplicates are of a clearly different plant conforming in all respects to B. penduliflora and it seems very likely that the two entities were found growing together. No other intermediate collections have been seen; the two species overlap in altitudinal range and possibly this aberrant collection might be a hybrid.

3. The allopatric (Philippine) B. multiflora is somewhat similar to B. listeri in the proportions and densely grey-hairy underside of its leaves, but it lacks the mixed indumentum and differs in abundant indumentum on leaf adaxial surface, prominent dorsal appendages on male flowers, thicker female inflorescence-bearing axes due to larger clusters and fruiting perianth usually with distinct wing.

4. Some variants of the sympatric (widespread) B. virgata subsp. macrophylla are superficially rather similar, especially those forms intermediate between var. macrostachya and var. scabrella which have inflorescence-bearing axes branched at the base and leaves relatively long and narrow with many small teeth; however, these forms do not have stem and petiole indumentum of mixed hairs of two different kinds and their leaves are clearly ovate rather than elliptic-ovate and drying greenish rather than greyish brown abaxially. Some variants of the allopatric (widespread) B. virgata subsp. virgata var. virgata are more similar in indumentum and leaf morphology but differ in marginal teeth relatively broader, fruiting perianth winged, female axes much longer (20–70 cm) and male axes also usually longer and branched throughout length.

5. The allopatric (Indonesian) B. rugosissima can have mixed stem indumentum and minutely bullate leaves almost glabrous adaxially, but leaves dry brownish rather than greyish and are usually much broader and stipules often very large.

6. A species of Cypholophus , C. decipiens Winkl. , (allopatric, Papua New Guinea and the Pacific) has strikingly similar leaves with markedly asymmetrical venation on the two sides (differing from B. listeri only in upper veins 0 – 2 rather than usually 3 on narrow side) and many minute teeth, sometimes also mixed stem indumentum, such that sterile material of B. listeri could be misidentified as this common and widespread species; however, on fertile material the sessile axillary female flower-clusters of C. decipiens are diagnostic.

7. Two collections of uncertain identity have been seen with relatively much broader leaves with length only c. 1.5 × width but otherwise conforming to B. listeri : Forest 24801 (UC), north-eastern Upper Burma (leaves obovate, only 6.5–9 cm long with abrupt short acumen); and Hooker et al. s.n. (NY), India, Sikkim (leaves elliptic 11–12 cm long).

Figures

Map 42 Distribution of Boehmeria listeri Friis & Wilmot-Dear.

Fig. 39 Boehmeria listeri Friis & Wilmot-Dear.a. Habit of stem with several bisexual inflorescence-bearing axes at each node; b. leaf; c. detail of lower surface of lamina, showing two types of hair; d. stipule; e. detail of male part of inflorescence-bearing axis with two flower-clusters (inflorescences) and bracts, showing two types of hair; f. male bud; g. detail of female part of inflorescence-bearing axis with one flower-cluster (inflorescence) and bract; h. fruiting perianth (a, c–g: Stainton 6723; b, h: Dec. 1890, King s.n.; all K). — Scale bars: a, b = 2 cm; c, e-h = 1 mm; d = 2 mm.