Boehmeria holosericea Blume

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 : 181-183

26. Boehmeria holosericea Blume — Fig. 32 ; Map 33

Boehmeria holosericea Blume (1857) 221. ― Boehmeria platyphylla D.Don var. holosericea (Blume) Wedd.(1869) 212. ― Type: Burger s.n. [L 908.185- 1666] (lecto L, selected here), Japan. – See Note 1.

Boehmeria hispidula Blume (1857) 223, syn.nov. ― Type: Burger s.n. [L908. 185-1665] (lecto L, selected here), Japan. – See Note 2.

Boehmeria gigantea Satake (1936) 513,syn.nov. ― Type: Nakai & Maekawa s.n. (holo TI), Japan, Honsyu, Suo, 22 July 1935.

Boehmeria quelpaertensis Satake (1936) 514 & Nakai (1936) 152, syn.nov. ― Type: Nakai 4999 (holo TI), South Korea, Quelpaert Island [Quelpart], 3 Nov. 1917. – See Note 6.

Boehmeria grandissima Nakai (1927) 18 [Japanese description only]; Nakai in Satake (1936) 514 [latin description]. ― Type: Nakai s.n. (holo TI, n.v., but photograph of type specimen in Satake 1936), Japan, Sikoku, Iyo, 9 June 1927.

Boehmeria grandissima Nakai var. serrulata Satake (1938c) 512. ― Type: Hatusima 25 (holo TI), Japan, Kyusyu , Tikuzen, Sikanosima Island [Peninsula], 1937.

Boehmeria tosaensis Miyazaki & H.Ohba (2003) 63,syn.nov. ― Type : Miyazaki s.n. (holo TI, photo K), Japan, Shikoku , Kochi Pref., Tosa, 10 Aug. 1992. – See Note 4 .

Robust erect woody-based herb, up to 1.5 m tall; ultimate stems robust, 1.5–2 mm; hairs dense, curved ± spreading, pale, soft minute (<0.2 mm) or rarely half-adpressed, sparser, slightly longer (up to 0.3 mm); later glabrescent. Stipules relatively broad, not markedly tapering to apex, 4–7 by 1.5–4 mm, thin-textured. Leaves opposite, not or slightly dimorphic in size only, ‘larger’ leaf with length of lamina up to 1.2 ×, but petiole up to 2 × length of ‘smaller’; very broadly ovate or deltate, usually medium or large, 10–25 by 7–21 cm, length equalling or up to 1.4(–1.7) × width; margin dentate or crenate, teeth (15–)20–27 either side, outward-pointing broadly rounded or broadly acute, large 3–10 by 5–15 mm, width 1.5–3 × length, distal ones progressively slightly longer and wider (length of distal teeth up to 2 × proximal ones) towards leaf apex or of ± uniform size along most of margin, but always short and indistinct near base; leaf apex with short abrupt acumen of single tooth up to 10(–20) mm, up to twice as long as distal teeth and rounded or mucronate at tip, sometimes some leaves also distinctly or indistinctly laciniate with a cleft either side near apex giving ± trilobed appearance; base broadly rounded, truncate or ± cordate (rarely slightly cuneate); basal veins extending into distal half of lamina, upper lateral veins similarly arranged on both sides, 1– 2 either side, arising in distal half, basal veins thinly prominent abaxially,upper veins and reticulation rather indistinct; texture chartaceous, often rather thin (rarely thicker and leaves slightly bullate); adaxial surface with hairs sparse to abundant, soft, curved, half-adpressed or spreading, often much longer than on stem (0.5–0.7 mm long); abaxial surface with hairs shorter (0.4–0.6 mm long), curved, (sparse-)abundant, often dense and velvety and concealing epidermis, abaxial surface paler than adaxial in dry state; petiole very variable 0.25–0.6 × lamina length, hairy as lamina. Flower­clusters borne on leafless axes, 1 per axil, mostly unisexual but often on same plant; male axes pendulous, 7–12(–15) cm long, (unbranched or) often with many short or long lateral branches throughout length, very occasionally main axis with tuft of leaves at tip, flower-clusters very crowded or well-spaced, 3–5 mm diam, with few(–20) flowers; female (or mainly female) axes erect, (7–) 15–20 cm long, mostly entirely female and unbranched but sometimes bisexual with a few very short male lateral branches near base, flower-clusters ± contiguous but distinguishable, 4–7 cm diam, with over 50 densely congested flowers; bracteoles tiny and inconspicuous in densely congested clusters. Male flowers 4-merous, sessile, mature buds depressed-globose, c. 1 mm diam, tepals without dorsal appendage or with slight dorsal thickening, hairy like stem. Female flowers ellipsoid to obovoid, relatively broad, c. 1 by 0.3 mm, distinctly beaked, densely hairy; stigma 1.5–2 mm long. Fruiting perianth slightly asymmetrically ellipsoid to obovoid-truncate, c. 2 by 1 mm, scarcely beaked, slightly laterally flattened with distinctly inflated winged shoulders, pubescent. Achene ellipsoid to ovoid, 0.4–0.5 by 0.8–1.2 mm, partly filling fruiting perianth.

Distribution ― South Korea (Jeju ‘Quelpart’ Island), Japan (Honshu, Shikoku, Kyusyu, Ryukyu Islands).

Habitat & Ecology ― Rocky areas near seashore; sunny or semi-shaded mesic plains along forest margins; at or near sea level (most collections lack habitat data).

Conservation status ― Data deficient (DD). We are not able to give a formal assessment of B. holosericea as either Least Concern (LC) or Near Threatened (NT), since its particular habitats are not currently threatened, but it is known from less than 20 collections, only a few of which are recent and it occurs in only 15 rather scattered locations.

Notes ― 1. No material is cited in the protologue of B. holosericea by Blume (1857), but Weddell (1869) cited only material collected by Burger. At L there are two sheets annotated by Blume with this name. One is only marked ‘B’, the other is marked ‘Burger’. We therefore select the specimen Burger s.n. as the lectotype of B. holosericea .

2. According to Blume (1857) his B. hispidula comes from “Sumatra, Palembang.” However, Koidzumi (1926: 346) has recorded two specimens as types: Burger s.n. [L 908.185- 1665] Japan, and Siebold [L 908.185-1680], without locality, and stated that Blume had apparently mistaken the locality for this plant. We have seen both specimens and select the one with the epithet in Blume’s original handwriting as lectotype.

3. This and the following two species, B. sieboldiana and B. japonica , are closely similar and appear to constitute a complex of partly intergrading taxa. Boehmeria japonica is extremely variable. Boehmeria holosericea and B. sieboldiana (partly sympatric with one another and both sympatric within part of the distribution of B. japonica and extending to the Ryukyu Islands) show much less morphological variation but exhibit intermediates with one another and with B. japonica . The extensive synonymy relating to B. japonica reflects the complexity of the inter-relationships between and within the taxa here recognised; partial apomixis within B. japonica further complicates the relationships.

4. Boehmeria holosericea is endemic to Japan and South Korea. Its spreading indumentum varies widely from dense and conspicuous to rather sparse, such that individuals at the extremes of the range of variation appear rather different but cannot be separated as distinct taxa because they are linked by a continuous range of intermediates. For this reason B. tosaensis , described in the protologue as “differing from B. gigantea on its sparse indumentum” is here reduced to synonymy.

5. Boehmeria holosericea is distinctive in its very broad leaves with large often rounded marginal teeth, some leaves being indistinctly trilobed at the apex and its thick crowded erect ± unbranched female inflorescence-bearing axes with clusters 4–7 mm diam.

6. The sympatric but more widespread B. japonica var. japonica has similar spreading indumentum, leaves often large and broad leaves with apex often trilobed. Boehmeria japonica differs from B. holosericea in marginal teeth acute and up-curved with distal ones progressively markedly larger than proximal ones (teeth usually also fewer) and apical tooth distinct, relatively longer and narrower; leaf-hairs are often minute, the leaf is never bullate and inflorescence-bearing axes are mostly pendulous with clusters often smaller and wider-spaced along the axis.As discussed in our introduction, Yahara (1983a) showed ecological, cytological and reproductive separation, B. holosericea being diploid and sexual, B. japonica var. japonica (cited as B. longifolia ) an apomictic complex of many polyploid races with occasional fertile male flowers. He did not find any evidence of hybridisation between the two species, although subsequently (Yahara 1984a: 141) he suggested one of these entities, B. quelpartensis , to be a hybrid between B. holosericea and B. japonica . However, the type of B. quelpartensis is extremely similar to that of B. holosericea and the two are here considered conspecific.

7. However, material intermediate between B. holosericea and B. japonica var. japonica has also been seen (teeth many, slightly up-curved and/or larger upwards, apex sometimes ± trilobed). This intermediate (possibly hybrid) material includes the types of the following names (including B. nakashimae , one of the entities studied by Yahara):

Boehmeria villigera Satake (1936) 516. ― Type: Satake 3541

(holo TI), Japan, Honsyu , Izu, 8 Sept. 1935 .

Boehmeria praestabilis Satake (1936) 519. ― Type: Satake

3544 (holo TI; iso TI), Japan, Honsyu , Izu, 5 Sept. 1935 .

Boehmeria nakashimae Yahara (1983b) 88. ― Type: K. Naka­

shima 15 (holo TI), Japan, Kyushu, Fukuoka City, 19 Sept.

1937.

Probably also the following type material:

Boehmeria quelpaertensis Satake forma glabra Satake (1936)

516. ― Type: Nakai s.n. (not traced), South Korea, Quelpart

Island, 3 Nov. 1917.

8. A range of entities of obscure identity with the same geographical range as B. holosericea also exists, having some characters of the often coastal sympatric species B. splitgerbera (2 kinds of hairs; leaves sometimes misshapen or slightly bilobed at apex; reticulation prominent) but marginal teeth fewer, larger, like those of B. holosericea . As discussed in our introduction Yahara (1983a: 242) suggested that these entities originated through hybridisation of B. splitgerbera with other taxa, the thinner-leaved forms possibly with the B. japonica complex. However, some of this thin-leaved material is so similar in leaf shape to B. holosericea that this is as likely a parent as B. japonica . The types of nine names, some of which were mentioned by Yahara, fall within this range of variation and are cited in Note 5 under B. splitgerbera .

9. Some other material without the distinctive bilobed leaf apex and lacking male flowers (therefore possibly apomictic) is impossible to assign with certainty to either B. holosericea or the above-mentioned probable hybrid populations.

10. Material intermediate (?hybrid) with the sympatric but more widespread B. sieboldiana has also been seen, discussed under that species (see Note 3). Boehmeria sieboldiana differs in much narrower gradually attenuate ± glabrous usually thin-textured leaves often with more numerous upper veins, male and female inflorescence-bearing axes with small usually well-spaced clusters.

11. Boehmeria ourantha ( China, Himalayas , Indonesia) is rather similar in leaf shape and marginal teeth to B. holosericea , but differs in extremely long stem indumentum, thicker-textured leaves with up-curved teeth and the unusual arrangement of its male flowers at the extreme apex of mainly female axes or a few male flowers scattered along the axis.

12. Marginal teeth are reminiscent of some forms of the variable B. virgata subsp. macrophylla s.lat. (allopatric) although larger, and two varieties of B. virgata subsp. macrophylla, var. macrostachya and var. strigosa , can have very similar leaf shape but stem hairs are inconspicuous and closely-adpressed, female inflorescence-bearing axes long, pendulous and slender with well-spaced clusters and male axes often short, erect and with several branches; var. strigosa also differs in shiny-silky indumentum on the abaxial leaf surface.

Figures

Map 33 Distribution of Boehmeria holosericea Blume.

Fig. 32 Boehmeria holosericea Blume.a. Habit of stem with inflorescence-bearing axes,lowermost entirely male,branched axes,uppermost bisexual branched, bisexual axes and unbranched female axes; b. leaf; c. leaf, detail of adaxial surface; d, e. leaves, detail of abaxial surface (different plants); f. detail of stem and stipules; g. detail of male inflorescence-bearing axis with flower-clusters (inflorescences) and bracts; h. male bud; i. detail of female inflorescence-bearing axis with congested flower-clusters (inflorescences) and bracts; j. fruiting perianth (a, c, d, g, i: Iwatsuki et al. 399, L; b, f: Furuse 42899, TI; e, j: Sieber s.n., L; h: Burger s.n. [L 908.185-1665], L). — Scale bars: a, b = 2 cm; c-f = 2 mm; g–j = 1 mm.