Gigantochloa compressa

Thai names: ไผ่คายดำ (phai khai dam) (Kanchanaburi); "ไผ่คายคำ" (phai khai kham) [in err.]; ไผ่ผากคายดำ (phai phak khai dam) (Chumphon, Surat Thani). — T. Smitinand, 2001 [#1003]; BKF [#1368].

Distribution: THAILAND (South): Provinces of Chumphon and Surat Thani; on hills and in lowland forests, at 50–250 m altitude. Assumed to grow also in Kanchanaburi Province of western Thailand (Classification of Bamboo, 2012 [#1223]). — MYANMAR: Mergui District of Tanintharyi Region (former Tenasserim), scattered along roadsides and in disturbed forests.

Descriptions:

(1) "Culms loosely tufted, straight and erect, 12—20 m tall, 4—10 cm in diameter; internodes to 72 cm long, glaucous when young then plain green, covered with appressed dark-brown hair on the upper half; nodes marked by the crustaceous, persistent bases of the fallen sheaths; walls about 4—8 mm thick. Branches developing only at the upper part of the culms, the primary one dominant, 1—2 subdominant branches from its base and several lesser branches. Culm leaves persistent, coriaceous, half the length of the internode, 32—38 cm long by 35—40 cm wide, top slightly convex, back covered with appressed dark-brown to black hairs; blades narrowly triangular, obtuse at the base, spreading to reflexed, 58—62 cm long by 5.8—6.2 cm wide near the base, adaxial densely covered with dark-brown to black hair but scattered in abaxial side; auricles continuing from base of the culm-leaf blade, low rim-like, reach edges of the sheath, about 3 mm tall by 3—8 cm long, margins denticulate; ligule extending to the full length of the sheath, fringed with pale-brown bristles 10—15 mm long. Leaves 6-8 per branchlet; blades 20—45 cm long by 3.5—7.5 cm wide, upper surface glabrous, lower surface slightly pubescent, bases acute to attenuate or oblique-attenuate, pseudo-petiole 3—10 mm long; leaf sheaths 7—14 cm long, covered with appressed dark-brown hair, margin golden-brown ciliate; auricles small rounded glabrous lobes to 1 mm tall by 1—3 mm wide; scale-like callus present, 0.5 mm tall, margin fringed with minuscule spines but become glabrous when old; ligule oblique, irregularly dentate to sub-entire 2—4 mm high, fringed with white to pale-brown bristles 5—10 mm long; secondary veins 7—14 pairs, intermediate veins 7. … [flowers described, seeds unknown]". — C. Rattamanee, Revis. Gigantochloa in Thailand, 2014: p. 80-84, fig. 24-25 [#1225].

(2) "… caespitose; clumped loosely. Rhizomes short; pachymorph. Culms erect; 1200–1800 cm long; 100 mm diam.; woody. Culm-internodes terete; hollow; 60 cm long; mid-green; distally pruinose. Lateral branches dendroid. Culm-sheaths persistent; 0.5 length of internode; hispid; with black hairs; auriculate. Culm-sheath ligule ciliate. Culm-sheath blade lanceolate; reflexed. Leaf-sheaths striately veined; pubescent. Ligule a ciliolate membrane; 1–2 mm long. Collar with external ligule; pubescent. Leaf-blade base with a brief petiole-like connection to sheath; petiole 0.3–0.5 cm long. Leaf-blades lanceolate; 20–45 cm long; 35–75 mm wide; glaucous. Leaf-blade venation with 14–28 secondary veins. Leaf-blade surface puberulous; hairy abaxially. Leaf-blade margins scabrous. Leaf-blade apex filiform; antrorsely scabrous. … [flowers and seeds described]." — Kew GrassBase [#1335].

Images: Photos of Burmese specimens in Kew Herbarium (leaves, leaf sheath, culm sheath, flowers) [#1333]. Post and photo by Thong Jumnarn‎ in Thailand Bamboo Forum on Facebook, 17 Apr. 2014.

Characteristics: Culms straight erect; young culms grey-powdery, striped, older green. Young shoots black, bitter. Culm-internodes about 60 cm long; walls 8 mm thick. Culm-nodes marked by a sharp edge. Culm-leaves persistent, half the length of the internode. Culm-leaf sheaths covered with black hairs when young, hairs very irritating. Culm-leaf auricles present, ciliate with long white bristles. Culm-leaf blade lanceolate, reflexed (R.N. Parker in Kew Herbarium, 1927 [#1333]).