Bambusa nghiana

Type: Vietnam, Thanh Hoa Province, Quan Son District, H. N. Nguyen HNN0067, holotype (DLU); cf. V. T. Tran, Adansonia 43 (19), 2021: 218 [#1371].

Thai names: ไผ่ซี้ (phai si), ไม้ซี้ (mai si) in Trat Province; ไผ่ปล้องยาว (phai plong yao) at Pang Sida National Park (อุทยานแห่งชาติปางสีดา) of Sa Kaeo Province; ไผ่นวล (phai nuan).

Vietnamese name: Lùng.

Distribution: THAILAND (East): Provinces of Prachin Buri and Trat, common along streams in dry evergreen forests at low altitudes, in evergreen forests at ca. 165 m altitude, and along roads and forest edges at ca. 700 m altitude; cf. W. Arthan & al., in Kew Bulletin, 2023 [#1396]. Also recorded from the central and eastern provinces of Prachin Buri, Sa Kaeo, Chantha­buri, Rayong, and Trat as wild (acc. to Mu Chakkrapong on Facebook, 19 Sep. 2017), and from Nakhon Nayok, wild, in forests (acc. to Mu Chakkrapong on Facebook, 2 Oct. 2021, and pers. comm., Facebook, 2 Oct. 2021). — VIETNAM (Northern): Quan Sơn District of Thanh Hóa Province: along roads and forest edges.

Descriptions:

(1) "Woody bamboo, rhizomes pachymorph, short-necked. Culm erect, plain color, green when young maturing to yellow, 13-15 m tall, 7-10 cm in diameter. Culm internode terete, basal internode covered with appressed pale hairs with a consistent narrow ring of dense appressed hairs at each node, with a slight white-waxy bloom just above, 60-80 cm long, or up to c. 100 cm long; wall thin, often less than 9 mm thick. Branches usually absent on lower culm, branches at mid-culm with the primary axis dominant in size with 2 or several higher-order subequal branches from its base. Culm sheaths on mature culm 25-35 cm long, pale green, infused with white green or yellow green at the top and dense black hairs at the base; basal part at the sheath insertion with a 2-3 mm long, narrow ring-like band of dense dark brown hairs 2-3 mm long; blade 5-8 cm long, broad triangular, erect, not tightly appressed against the next sheath or internode[,] green, with a slight white-waxy bloom on abaxial side, with 1-2 cm long pale brown bristles at the base of the margins; auricles 7-10 mm high, protruding, 1-2 cm long and slightly upcurved at the end, purplish brown with sinuous bristles on the edge 5-10 mm long, ligule a leathery low subentire rim 2-2.5 cm high with narrow triangular margin teeth. Leaves 18-20 × 2.9-3 cm, green on the adaxial side and white green on the abaxial side, glabrous on both surface; auricles with a conspicuous laterally spreading narrow lobe 0.5-1 mm high and 1-2 mm long, upcurved at the end, margins with spreading bristles 1-2 cm long; ligule inconspicuous; sheath glabrous. … [flowers and seeds described]". — V. T. Tran, in Adansonia 43 (19), 2021: p. 217-221 [#1371].

(2) "Perennial arborescent bamboo, unarmed. Rhizomes a pachymorph with short necks, sympodial; forming a dense clump with relatively well-spaced culms. Culms erect, up to 15 m tall, tips arching to drooping; nodes not swollen; nodal line horizontal, more or less the same diam. as the adjacent internodes, with a ring of patent rusty brown hairs; supranodal ridge inconspicuous, with a band of pale to white hairs above; aerial roots absent; internodes dull green, 50 – 150 cm long, 3 – 8 cm in diam., covered with white to rusty brown hairs and thick white wax when young, greyish-green and glabrous when mature; walls thin, 4 – 8 mm thick mid-culm. Branch buds at each culm node solitary. Branches developing from the base or from around mid-culm upwards. Mid-culm branch complements with several branches per node; middle branch dominant, 1/3 – 1/2 the diam. of the main culm; 2 associated, smaller, secondary branches; basal, smaller branchlets few. Culm leaves deciduous; sheaths purplish to brownish-green when young, greyish to yellowish-green when mature, 15 – 35 cm, covered with thick white wax, and brown to black hairs when young, margins scarious, base of outer margin with a slight projection below the point of attachment; blades spreading or patent, occasionally deflexed, purplish-green when young turning green when mature, broadly triangular to lanceolate with some constriction at the base, 4 – 8 cm long, base less than 1/3 width of sheath; auricles present and contiguous with the base of the blade, protruding laterally from the sheath margins, lobe-like, up to 2 cm long, more or less unequal, oral setae present, bristles 0.5 – 1.5 cm long; ligules a leathery, low, subentire rim, 2 – 5 mm high, margin with teeth 1 – 8 mm long, irregularly denticulate to bristly. Foliage leaves with sheaths 3 – 6.5 cm long, glabrous; blades lanceolate, 15 – 35 × 1 – 3.8 cm, apex acuminate, glabrous on both sides, abaxially glaucous; auricles conspicuously lobed, lobes 1 – 2 mm long, margins with bristles up to 1 cm long; ligules inconspicuous. … [flowers and seeds described]". — W. Arthan & al., in Kew Bulletin, 2023 [#1396].

Images: Photos and line drawings in V. T. Tran, l.c., 2021: p. 219-220 [#1371]; photos in W. Arthan & al., l.c., 2023 [#1396].

Uses: Locally in Vietnam: Shoots for food, culms for house construction and handicrafts. Locally in Thailand: Shoots edible, and said to be eaten by locals; culms for woven bamboo hats (Mu Chakkrapong, l.c.) and other handicrafts.

Flowering and seeding: The specimen, BS-0599, was not perceived as flowering until late March 2021. Since all the flowering occurred in the upper parts of the plant, and all the branches were entangled with tall trees and other bamboo plants, the flowering was not immediately noticed. Presumably, flowering began in February or early March. In early April 2021, it could not be said whether the flowering would be sporadic or gregarious, but by mid-April, it became clear that the latter was happening. Spikelets were found on the ground in late March, and many of them contain seeds. With the start of the rainy season in April/May, numerous seeds germinated on the ground, and seedlings developed. The mother plant died soon thereafter.

Seed weight: 20 seeds weigh 1.31 g → ≈15 seeds/g.

Seed germination: 10 seeds laid on moistened coir dust on 31 March 2021, 19–32 °C day, diffuse light, 18–28 °C night, atmospheric humidity 60–99%, 6 coleoptiles emerged by the 5th day, the first leaves developed by the 8th day; a germination rate of over 50% can be expected (test 210331).

Seed viability: unknown; viability could only be a few weeks. Seed germination trials were carried out by three people from Europe, Central America, and South America; each person received 15 seeds 1–2 and 2–3 months after harvest, respectively. None of these seeds germinated. While there can be many reasons for unsuccessful germination, I would not rule out that the seeds of BS-0599 lack dormancy and therefore only have a short lifespan.

Cultivation requirements: easy-growing, thrives well in heavy, moist soil with good drainage, and in partial shade.

Comments:

(1) Prior to flowering, BS-0599 was assumed to belong to Melocalamus or Maclurochloa as they shared similar vegetative characteristics, e.g., growth habit, branch complement, shape and size of culm-leaves, conspicuous bristly auricles, inconspicuous ligule, hairy sheath scar-ring.

(2) When flowers and seeds of this species were found in Thailand in 2019, it was soon found out that Bambusa is the appropriate placement, despite the vegetative characteristic of the branch complement in BS-0599 (which is uncommon if not hitherto unknown in Bambusa) (Mu Chakkrapong, pers. comm. Facebook, 23 and 25 Feb. 2019, 20 and 25 Mar. 2021).