Gigantochloa balui

Thai names: ไผ่บาลุย (phai ba lui). ไผ่มัน (phai man) (Surat Thani); ไผ่ตากวาง (phai ta kwang) (Phang Nga); ไผ่ผาก (phai phak) (Surat Thani, Krabi, Nakhon Si Thammarat) — C. Rattamanee, Revis. Gigantochloa in Thailand, 2014: p. 75 [#1225]; BKF [#1368].

Malay name: Balui.

Distribution: THAILAND (South): occurs wild in the lowlands, on river banks, secondary forests, and disturbed areas, at 50–100 m altitude. — MALAYSIA (Peninsular): Kedah, wild and rare; (Borneo): Sabah, Sarawak, only in cultivation. — INDONESIA: Java, West Kalimantan, cultivated. — BRUNEI, cultivated. — N. Bystriakova & al., Bamboo Biodiversity, 2003: map 33 [#1342].

Descriptions:

(1) "Densely tufted sympodial bamboo. Culm erect, slightly arching outwards, up to 12 m tall, diameter 3–8 cm near the base, plain green or white or pale yellow stripes at the base; internodes non-waxy, up to 40 cm long, covered with appressed pale silver hairs; nodes not conspicuously swollen. Branch complement at each midculm node arising from a single bud, consisting of a dominant primary branch, 1–2 subdominant branches from its base and several lesser branchlets of higher orders. Culm sheath pale green, sometimes with faint yellow stripes, covered with appressed pale silver hairs; blade broadly triangular on lower sheaths, green or sometimes flushed purple, spreading to reflexed; ligule lacerate, the base 1–3 mm long, the lacerations to 4 mm long; auricles low and rimlike, up to about 2.5 mm tall, glabrous, dark green to dark purple. Leaf blade 20–35 cm × 2–4 cm, lower surface slightly glaucous and hairy; ligule a low glabrous rim to c. 1 mm long; auricles small rounded glabrous lobes to c. 1 mm long … [flowers described, seeds unknown]". — K. M. Wong in S. Dransfield & E. A. Widjaja (eds.), Plant Resources of South-East Asia No. 7, Bamboos, 1995: p. 106-107, fig. [#1226].

(2) "Culms densely tufted, straight and erect, up to 12 m tall, 3—8 cm in diameter, tips slightly arching outwards; internodes to 40 cm long, plain green or pale stripes at the lower ones, non-waxy, covered with appressed pale silvery hairs all over; nodes not conspicuously swollen, covered with white sericeus ring above and below nodes; walls relatively thin, about 0.6—1 cm thick (mid-culm portion). Branches developing from around mid culm upwards; mid-culm branch complements with several branches at each node arising from a single bud, the primary one dominant, 1—2 subdominant branches from its base and often several smaller branches. Culm leaves deciduous, coriaceous, yellow-green, 23—25 cm long by 18—22 cm wide, sheaths apex truncate with slightly convex in the middle, back covered with appressed pale silver hairs; blades, slightly decurrent, green sometimes with flash purple, broadly triangular on lower sheaths, broadly lanceolate on mid-culm or upper sheaths, spreading to reflexed, 14—25 cm long, about 2—4.5 cm wide near the base, adaxial base covered with hispid golden-brown hairs; auricles low and rimlike up to 2.5 mm high, glabrous, green to dark green continuing from base of culm-leaf blade; ligule lacerate, the base 1—3 mm high, fringed with golden bristles to 4 mm high. Leaves 6—14 per branchlet; blades 13—26 cm long by 2—3 cm wide, lower surface slightly pubescent, bases acute, pseudo-petiole 2—5 mm long; leaf sheaths 7—10 cm long, glabrous; auricles small rounded glabrous lobes to 1 mm. long, margins glabrous; scale-like callus present, one side crescent, another one broadly-triangular, 1 mm by 3 mm, margin slightly undulate-ciliate; ligules up to 2 mm high, slightly oblique, margin lacerate to ciliate; secondary veins 8—10 pairs, intermediate veins 5—7. … [flowers described, seeds unknown]". — C. Rattamanee, Revis. Gigantochloa in Thailand, 2014: p. 74-79, fig. 21-23 [#1225].

(3) "… Rhizomes short; pachymorph. Culms erect; 1000–1200 cm long; 60–80 mm diam.; woody. Culm-internodes terete; thin-walled; 20–40 cm long; light green; distally pubescent. Lateral branches dendroid. Bud complement 1. Branch complement one, or two, or three. Culm-sheaths pubescent; with appressed hairs; with white hairs; auriculate; with 2.5 mm high auricles; ciliate on shoulders. Culm-sheath ligule 4 mm high. Culm-sheath blade lanceolate; spreading, or reflexed. Leaf-sheath auricles erect; 1 mm long. Ligule an eciliate membrane; 1 mm long. Collar with external ligule. Leaf-blade base with a brief petiole-like connection to sheath. Leaf-blades lanceolate; glaucous. Leaf-blade surface pubescent; hairy adaxially. …" — Kew GrassBase [#1335].

Images: Photo in K. M. Wong, Bamboo - The Amazing Grass, 2004: fig. 55 (shoot) [#1048].

Uses: Culms for walls, flooring, basketry, fishing stakes, sailing masts, framing; internodes for handicrafts and as cooking vessels. Shoots edible.

Comments:

(1) Although dried culms of Gigantochloa balui populations from regions other than Nakhon Si Thammarat Province develop some dark spots and streaks, streaks on culms from Nakhon Si Thammarat are more pronounced, generally longitudinal, and overall more attractive. Populations in Nakhon Si Thammarat are considered wild, and it is unknown whether they should be classified as a variety within the species or whether these are sports that frequently develop within these populations. However, it is certainly helpful to separate these variants at the cultivar level, as plants are often taken into cultivation and their cut culms are used for their decorative appearance.

(2) Based on just a few photos and two videos of ไผ่ลายพระนาย (phai lai phranai) initially, I was pretty sure it was a Gigantochloa species, but I could not identify the species. Thanks to Mu Chakkrapong (pers. comm., Facebook, 13 Nov. 2021) for pointing out that this is probably Gigantochloa balui. The further comparison with photos of Gigantochloa balui provided by Mu Chakkrapong, as well as the comparison with two Gigantochloa balui plants from Thailand and Malaysia, both in cultivation at Bambusetum Baan Sammi, convinced me that the identification is correct. In addition, I thankfully received from Mr. Siraphop a living plant, ไผ่ลายพระนาย (phai lai phranai), from Nakhon Si Thammarat, 20 Nov. 2021, which was planted out at Bambusetum Baan Sammi in November 2021.