Eskemukerjea megacarpum (H. Hara) Hara (1982: 173)

Gou, Yu-Ting, Zhu, Zhen-Hua, Zhou, Xin-Xin, Chen, Yong-Jun & Li, Bo, 2022, The first record of the genus Eskemukerjea (Polygonaceae) from China, Phytotaxa 577 (1), pp. 139-144 : 141-142

Eskemukerjea megacarpum (H. Hara) Hara (1982: 173)

≡ Fagopyrum megacarpum Hara (1972: 9) .

Type:— NEPAL. Dhaulagiri Zone, Mugu Kamali Valley , between Daura and Mangri, 28°15′10.83″ E, 83°56′18.77″ N, 15 August 1952, Polunin, Sykes & Williams 3033 (holotype: BM000065579 !, image available at https://data.nhm.ac.uk/object/fb4c41e2-9727-45b4- 9597-4461dc93b893; isotypes: E00012335 !, image available at https://data.rbge.org.uk/herb/ E00012335 ; UPS-V-145070!, UPS-V-145071!, UPS-V-145074!) .

= Eskemukerjea nepalensis Malick & Sengupta (1972: 433) .

Type:— NEPAL. Karnali Zone, Jumla , elev. 3000 m, September 1963, Itoh & Rajbhandari 1175 (holotype: CAL0000020709 !, image available at https://ivh.bsi.gov.in/r-Error?link= CAL0000020709 &tbl=3) .

Description ( Fig. 1 ):—Herbs perennial. Tuberoid huge, 5.5–25.0 × 2.5–13.5 cm, atractoid, ellipsoid, to nearly globose. Stems shooting from the tuberoid, many, slender, fistular, twining and climbing, up to 15 m long, terete, slightly ligneous at the base, much branched, striate, glabrous except puberulent near nodes, with dense red to purple spots. Leaves petiolate, alternate, simple; petiole 0.5–11.5 cm long, grooved and puberulous above, glabrous beneath, usually curved near base; leaf blade broadly ovate-cordate to ovate-triangular, 2.1–15.5 × 1.8–14.0 cm, abaxially sparsely pubescent along veins, adaxially glabrous, penninerved, basal nerves 5–7, lateral nerves 4–7, prominent beneath, base deeply cordate (lobes 0.8–4.5 cm long), margin entire to slight sinuate, minutely ciliate, apex acuminate, entire to sinuate in the lower half. Ocrea triangular, membranous, 4–6 mm long, glabrous but pubescent around the base, densely covering red to purple spots, apex acute, oblique. Inflorescence axillary and terminal, paniculate, lax, 4.2–9.5 cm long; peduncle 2.1–5.8 cm long, sparsely pubescent; bracts greenish, ovate, acute, 2–6 mm long, glabrous; bracteoles narrowly lanceolate to linear-lanceolate, each 4–5-flowered. Pedicel 3–13 mm, slender, glabrous, articulate below middle. Perianth greenish white; tepals 5, elliptic, 2.5–3.5 mm long, base connate into a short obconic tube, 3-nerved from base. Nectaries 8, free, nipple-like, 0.2–0.3 mm long. Stamens 8, equaling perianth, inserted and alternating with nectaries; filaments glabrous, 1.5–2.9 mm long; anthers oblong, 0.5–0.9 mm long, purple. Styles 3, 0.8–2.2 mm long, free up to base; stigmas minutely capitate. Achenes light-brown, ovoid, 7.5–12.5 × 7.2–12.3 mm, much exceeding the persistent perianth, broadly 3-winged, glabrous; wings slightly coriaceous, oblong, 7.5–12.5 mm long, entire, with nerves radiating outwards; seeds pyramidal, 6.4–7.1 × 3.8–4.3 mm.

Illustrations: — Malick & Sengupta (1972: 434, Plate A–G); Hara (1972: 139, Fig. 2b ); Ohsako et al. (2001: 10, Fig. 1 ).

Phenology: —Flowering time from early July to September; fruiting time from August to late October.

Distribution and habitat: — Eskemukerjea megacarpum was previously recorded only from mountains of Nepal. Based on the data from historical collections and our new records, E. megacarpum occurs mainly along the south slopes of the Himalayas ( Fig. 2 ), grows near forests, roads, riverbanks, or valleys from 1800–2900 m a.s.l., and always climbs on trees or shrubs. Most of its known distribution sites were located around the border between China and Nepal, but the new discovery of the species from Medog County of Chinese Tibet, which is far from the China-Nepal border, may indicate that there are probably other potential populations in the southern Himalayas.

Morphological notes: — Eskemukerjea megacarpum has a huge tuberoid which is partially uncovering upon the ground and attractive in the field ( Fig. 1H ). Hara (1972) has noticed this trait reporting it when describing Fagopyrum megacarpum , while Malick & Sengupta (1972) did not mention this characters when they described E. nepalensis . In living plants, the stems densely cover remarkable red to purple spots ( Fig. 1F ), which disappear when dry. The petioles are usually curved near base ( Fig. 1F ) which have not been described in both Hara (1972) and Malick & Sengupta (1972). The size of leaf blades and the length of petioles shows an high variation, whereas the shape of the blades is stable. Each bracteole usually encompasses 4–5 flowers in bud but only 1–2 flowers could develop at a certain time and their pedicels would much more elongate than the rest. There are 8 nipple-like free nectaries in a flower and the stamens are alternately inserted, partly in accordance with the description of “glandular disc” in Malick & Sengupta (1972).

Taxonomic note: —With the achievement of molecular phylogenies of Polygonaceae in the recent 20 years, phylogenetic positions and circumscription of most genera have been well resolved. Eskemukerjea , up to date, is the only genus of the family that has not been certainly placed at tribal rank. It is morphologically similar to Pteroxygonum (tribe Pteroxygoneae T.M.Schust. & Reveal ) and Fagopyrum (tribe Fagopyreae Yonek. ) (see e.g., Malick & Sengupta1972, Hara 1972), but phylogenetically related to Rumex or Rumiceae ( Ohsako et al. 2001, Sanchez et al. 2011). Galasso et al. (2009) had provisionally placed Eskemukerjea under Fagopyreae but additionally noted that it may not belong to this tribe. The newly collected materials of E. megacarpum in China provide us a precious opportunity to confirm its phylogenetic position within the subfamily Polygonoideae based on a large-scale phylogenetic analysis with more comprehensive sampling and data.

Additional Specimens examined: — CHINA. Tibet Autonomous Region: Nyingchi City, Medog County, Beigeng Town, Gelin Village , near a road, elev. 1800 m, 95°10′42 E, 29°13′12″ N, 18 August 2022, Zhou 2022081801 (JXAU!) ; Shigatse City, Gyirong County, Gyirong Town, elev. 2764 m, 85°20′13″ E, 28°23′29″ N, 20 July 2021, Xu LB1094 (JXAU!) ; Langjiu Village, elev. 2895 m, 85°21′45″ E, 28°24′08″ N, 10 September 2021, Guo & Wang LB1099 (JXAU!) ; NEPAL. Bagmati Zone, Rasuwa District , Lama Lodge , elev. 2470 m, 85°25′56″ E, 28°09′40″ N, 24 July 1992, Central Nepal Expedition 9220401 (E00238249!, TI!) ; Central Nepal Expedition 9239227 (E00232608!) ; Syarpagoan-Langtang, in a forest, elev. 2590 m, 31 July 1949, Polunin 1370 (BM000065440!, E00012336!) ; Karnali Zone, Dolpa District , Rachi , ascending on a tree up to 4 m in Picea , elev. 2890 m, 9 October 1991, Botanical Expedition to West Nepal 9108192 (E00132189!, TI!) ; Humla District, between Pyusa and Bokche Gauda , W facing slope, elev. 2260 m, 81°52′1″ E, 29°53′8″ N, 17 June 2008, Flora of Nepal Collecting Trip A160 (E00392160!, TI!] ; East of Jumla, Lorpa , growing over shrubs, 31 July 1952, Polunin , Sykes & Williams 4961 (BM000065442!, E00012337!) ; Suli Gad, elev. 2438 m, 82°51′ E, 29°0′ N, 7 July 1966, Stainton 5493 (BM000065443!, BM000065444!, BM000065445!) ; Bheri Zone, Tarakot , Bheri river, on shrubs covered slopes, 13 July 1952, Polunin , Sykes & Williams 2439 (BM000065441!, E00012334!) .

Figures

FIGURE 1. Eskemukerjea megacarpum. A. Holotype (Itoh & Rajbhandari 1175, CAL0000020709; © copyright Botanical Survey of India) of E. nepalensis (from Malick & Sengupta 1972: 434); B. Holotype (Polunin, Sykes & Williams 3033, BM000065579; Creative Commons Attribution CC BY and © copyright The Trustees of the Natural History Museum, London); C. A newly collected specimen (Guo & Wang LB1099, JXAU) from Gyirong County of Tibet, southwestern China; D. Habit and habitat photographed from Medog County of Tibet; E. An individual collected from Gyirong County and transplanted to the Shanghai Chenshan Botanical Garden greenhouse, showing the twining stems; F. Ocrea and partial stem and petiole, showing the dense red to purple spots; G. Young inflorescence; H. Tuberoid with buds; I. Leaves; J. Achene; K. Styles.

FIGURE 2. Distribution map of Eskemukerjea megacarpum. The green polygons indicate known localities in Nepal (numbers 1 and 2 mark the type localities of E. megacarpum and E. nepalensis, respectively); red circles represent the newly discovered localities in China.