Schizostachyum pergracile (Munro) R.B.Majumdar

Sungkaew, Sarawood, Wong, Khoon Meng, Hodkinson, Trevor R., Thammanu, Siriluck, Cheysawat, Somboon & Teerawatananon, Atchara, 2024, Taxonomic revision of the bamboo genus Schizostachyum (Bambusoideae: Melocanninae) in Thailand, with two new species and five new records, lectotypifications and nomenclatural corrections, Phytotaxa 676 (3), pp. 263-286 : 280-281

(13) Schizostachyum pergracile (Munro) R.B.Majumdar (in Karthikeyan et al. 1989: 282). Figs. 2E–F .

≡ Cephalostachyum pergracile Munro (1868: 141) .

Type: — MYANMAR, Pegu, Tenisserim, Tingwa, Brandis 11 (lectotype here designated:W [W19160012082, digital image!]; isolectotypes: K [K000912132 & K000912133, digital images!]) .

Description: — Culms erect, 9–15 m high, tips drooping; internodes green when young, light green to greyish green when mature, 20–70 cm long, 2.5–8 cm in diameter, covered with thin wax and white to pale brown hairs; walls 0.5–3 mm thick; nodes with slightly prominent nodal line. Culm leaves: sheaths yellowish brown to reddish brown throughout, up to 18 cm long, apex symmetrical, concave, densely covered with stiff black to dark brown hairs on abaxial side; auricles undulate or plicate lobed, 0.5–1 cm high, oral setae 0.7–1.5 cm long; ligules 1–2 mm high, irregularly toothed, ciliolate; blades erect then spreading, sometimes becoming deflexed, yellowish to reddish brown throughout, ovate to cordate, up to 9 cm long, inflated outwards, densely setose to villous on adaxial side. Foliage leaves: auricles inconspicuous, oral setae ca. 1.9 cm long; ligules up to 1 mm high, irregularly toothed, ciliolate; blades 15–35 × 2.5–3.8(–6) cm, scabrous to glabrous on both sides. Pseudospikelets green, usually in dense bracteate cluster, fusiform, 1.4–1.7 cm long; empty glumes 1; rachilla internodes very short, less than 0.5 mm long; fertile florets solitary, 1.3–1.5 cm long, with terminal rachilla extension 0.9–1.1 cm long, and with a tiny vestigial floret; lemmas 1.2–1.4 cm long, apex long mucronate or awned, usually densely hairy toward apex; paleas 1.3–1.5 cm long, keeled, hairy on abaxial side. Lodicules 3. Stamens: anthers greenish to yellow, 5–7 mm long; filaments free.

Distribution and ecology: — Schizostachyum pergracile exists in almost all regions in Thailand except peninsular Thailand. It is usually found in large populations and distributed in vast area in mixed deciduous forest at altitudes from 100–1,000 m

Additional specimens examined: — THAILAND: Northern. Mae Hong Son, Mae Lah Noi , 14 December 1996, P. Po-ngae 252 ( BKF117220 ) ; Mae Pai , 7 June 1995, C. Niyomdham et al. 4196 ( BKF119015 ) ; Chiang Mai, Doi Chiang Dao , 20 February 1957, K. Bunchuai 338 ( BKF18831 ) ; Doi Sutep , 18 June 1987, J.F. Maxwell 87-695 ( BKF93068 ) ; Mae On , 30 October 2003, A. Teerawatananon & S. Sungkaew 2003-0241 ( Thailand Natural History Museum) ; Mae Rim , 24 October 1997, S. Dransfield & P. Thongsorn SD 1435 ( BKF125696 ) ; Chiang Rai, Meh Yao , 19 December 1983, E.F. Anderson 5367 ( BKF108711 ) ; Nan, Na Muen , 28 October 2022, S. Sungkaew & A. Teerawatananon 1754 ( Thailand Natural History Museum) ; Lampang, Muang Bahn , 14 February 1996, J.F. Maxwell 96-289 (BKF114736, L0361432 , L0361433 , L0361434 ) ; Jae Hom , 8 January 2012, J.F. Maxwell 12-1 ( L2059013 , L2059014 , L2059015 , L2059016 , L2059017 , L2059018 , L2059019 , L2059020 , L2059021 , P01182939, P01182940) ; Kamphaeng Phet, Mae Wong National Park, 15 June 1995, C. Niyomdham et al. 4414 ( BKF118737 ). North-eastern. Phetchabun, Lom Kao , 6 January 1960, T. Smitinand 6324 ( BKF24895 ) ; Loei, Chiang Khan , 6 November 1997, S. Dransfield et al. SD 1471 (BKF126826, K000682148) ; Phu Rheua National Park , 7 November 1997, S. Dransfield et al. SD 1474 (BKF125983, BR927279 ) ; the same locality, 7 November 1997, S. Dransfield et al. SD 1475 ( BKF125968 , L0361435 ) ; Sakon Nakhon, Waritchaphum , 18 February 2006, W. McClatchey et al. WCM3769A ( BKF154141 ). South-western. Kanchanaburi, Huai Khayeng, 23 September 2023, S. Sungkaew & A. Teerawatananon 1808 ( Thailand Natural History Museum) ; Kroeng Krawia , 5 February 1962, K. Larsen 9579 ( BKF27198 ) ; Thong Pha Phum, Linthin , 25 August 1999, T. Wongprasert s.n. ( BKF129838 ) ; the same locality, 15 January 2002, S. Sungkaew & A. Teerawatananon 050102-1 ( Thailand Natural History Museum) . MYANMAR: Pegu, August 1889, D. Brandis s.n. (K001097802) .

Conservation status: — Schizostachyum pergracile has an EOO of 212,871.0 km 2 which places it in the Least Concern (LC) conservation category while its small AOO of less than 500 km 2 (76.0 km 2) yields the Endangered (EN) category. However, this bamboo species is widespread across the country except the southern part. Many populations together with many individuals are commonly found both inside and outside protected areas in a vast area. Small plantations of this bamboo species were also found to be raised for its culm utilization. According to IUCN (2023) criteria, we consider the conservation status of S. pergracile is LC.

Vernacular name: —ขุยป้าง (Khui Pang), ไผ่ข้าวหลาม (Phai Khaolam), ไผ่ข้าวหลามกาบแดง (Phai Khaolam Kab Daeng), ไผ่เปาะ (Phai Po).

Notes: —Young culms of S pergracile are used as containers for making traditional a Thai sweet delicacy named Khao Lam, a sweet sticky rice cooked in grilled bamboo culm.

Nomenclatural notes: — Two specimens collected by J. McClelland from Rangoon and D. Brandis from Pegu, Myanmar were mentioned in the protologue ( Munro 1868) without the holotype designation. Thus, the two specimens were considered syntypes. Here, a lectotypification was carried out by designating Brandis’s specimen deposited at W (W19160012082) as the lectotype and the other two from K (K000912132 and K000912133) as the isolectotypes.

Figures

FIGURE 2. (A–B) Schizostachyum brachycladum (Kurz) Kurz. (A) Culm internode with culm leaf; (B) Young culm shoot. (C–D) S. grande Ridl. (C) Young culm shoot; (D) Culm leaf on culm internode. (E–F) S. pergracile (Munro) R.B.Majumdar. (E) Culm internode with culm leaf; (F) Young culm shoot. (G–H) S. zollingeri Steud. (G) Culm leaf on culm internode; (H) Young culm shoot. (I–L) S. chinense Rendle. (I) Clump habit; (J) Young culm shoot; (K) Young culm showing culm leaf characteristics (with concave and inflated apex of the sheath proper, and erect blades) and a node; (L) Flowering branch. (Photographed by A. Teerawatananon & S. Sungkaew).