Gigantochloa sp. (TH: Phetchabun) 1
Gigantochloa sp.
Thai name: ไผ่ดำลำตัน (phai dam lam tan).
English name: Thai Black Solid Bamboo.
Distribution: THAILAND (Central, North-East), between Phetchabun Province and Loei Province, wild, rare, in mountains at about 600 m altitude.
Culm size: Not recorded, height is over 15 m, diameter to 6 cm or more.
Specimen: BS-0041 [W4] (living plants), coll. by ธ. ล. between Phetchabun and Loei in the wild, received 5 Sep. 2011.
Gigantochloa sp. from Phetchabun (BS-0041): Node on lower culm, the central dominant branch remains dormant, 1-year-old culm (left); internode on lower 1-year-old culm, showing the black color which has developed after almost 1 year (center); young shoot, showing the upper part of a fresh culm-leaf, with rim-like auricles, a very tall lacerate ligule, and a reflexed blade, hairy on its upper part near the attachment to the sheath (right)
Characteristics: Habit tight caespitose. Rhizome pachymorph, short [n.v.]. Culms erect, straight, over 12 m long [ultimate size currently not known], apically arching. Young shoots green, with scattered dark hairy patches, with culm-leaf blades patent, emerge from June to October. Culm-internodes terete, 30–40 cm long, initially green and with very short, soft, caducous pale hairs, becoming glabrous, slightly rough and dull, not glossy, deep black towards the end of the growth period, not farinose; diameter 6.0 cm [ultimate size currently not known]; thick-walled, solid or nearly so on the basal culm, walls 1.5 cm by 5.6 cm in diameter at 2.9 m above the ground. Culm-nodes glabrous, smooth, not prominent, green when young, blackish green when old; supranodal line clearly discernible; aerial roots none; nodes on branches somewhat prominent. Branch-buds solitary, from the basal node up. Branches on the lower culm none, with the bud remaining dormant but very short and very thin side branches may occasionally develop; the mid-culm often with 1 thick long branch, to 5 m long; the upper culm with few to many thin subequal branches, often 1–3 slightly dominant and longer; branching intravaginal, rebranching. Culm-leaves early deciduous. Culm-leaf sheaths 22 cm wide at the base, 25 cm long, rigid, coriaceous, green when young, straw-colored when dry, covered with appressed short black hairs, except near margins and apex, the hairs denser towards the sheath base; margins eciliate; apex slightly concave truncate, 6–7 cm wide. Culm-leaf auricles rim-like, long, 2 mm high, the rim margin eciliate, ending less high and rounded before but close to the sheath margin, greenish-orange when young, becoming blackish soon. Culm-leaf ligule very high, up to 5 cm, blackish when young, straw-colored when dry, papery, margin irregularly shaped, notched, initially lacerate with a few whitish bristles, later eciliate, recurved and deeply cleft when old, crumbling in part when old. Culm-leaf blades coriaceous, caducous, strongly reflexed (on the mid-culm), lanceolate, 2–2.5 cm wide at the junction with the sheath apex, about one-third of the sheath apex width, 18 × 4 cm, shorter than the sheath on the lower culm, usually 1/2–1/3 of the sheath length, as long as or longer than the sheath on the mid-culm and upper culm, green with purplish tint when young, soon becoming dry and straw-colored, adaxially densely hairy near the junction with the sheath, abaxially glabrous. Foliage-leaves 8–10 per branchlet. Foliage-leaf sheaths green, sparsely pale hispid; apex reddish when young. Foliage-leaf auricles inconspicuous or none, without bristles. Foliage-leaf ligule low, entire, eciliate. Foliage-leaf blades thin, medium-sized to small, 12–25 × 1.2–2 (3) cm, linear-lanceolate, mid-green, glabrous above, finely pubescent beneath when young, becoming glabrous soon; base rounded to wedge-shaped; apex attenuate; margins antrorsely scabrous; midrib not prominent; pseudopetiole 1–2 mm long. Flowers and seeds are unknown.
Uses: Not recorded. Can be planted as a feature bamboo in gardens and for landscaping.
Cultivation requirements: Grows best in light shade, soil can be heavy loam, normal moisture-retentive to moist with good drainage.
Provisional identification: The species is tentatively assigned to Gigantochloa for its rim-like culm sheath auricles.
Comments: The general appearance of this species, mainly its habit and small leaves, is similar to Phai Liang, ×Thyrsocalamus liang, but they are certainly not conspecific.
Gigantochloa sp. (BS-0041): Foliage leaves
Specimen: BS-0047 [†] (living plant), collected by ธ. ล. in จ. เพชรบูรณ์ Phetchabun "from the wild" at about 800 m altitude, the plant received as "ไผ่เลี้ยงยักษ์ (phai liang yak)", 31 Oct. 2011, died in 2012.
Characteristics: Culms, culm-internodes (green), nodes, branches, and foliage-leaves match characteristics of ไผ่เลี้ยง (phai liang), ×Thyrsocalamus liang, but other characteristics could not be observed because the plant died early. Culm-leaves were not available.
Comments:
(1) According to the plant collector, BS-0047 is similar to ไผ่เลี้ยงดำ (phai liang dam) (×Thyrsocalamus liang), but culm height is taller and culm diameter thicker in the former. Therefore, the collector named this bamboo ไผ่เลี้ยงยักษ์ (phai liang yak) /ˈpʰàj ˈlíːaŋ ˈják/; yak = giant. It is not possible to determine whether BS-0047 is conspecific with BS-0041.
(2) However, there are not only two specimens, BS-0041 and BS-0047, which undoubtedly show similarities in their vegetative characteristics, but three: The third specimen is BS-0042, and dealt with in detail under ×Thyrsocalamus liang. All three specimens were collected by the same plant collector, all in the same region and within two months of the same year, and all three were claimed to occur in the wild. BS-0042 is most likely a genuine ×Thyrsocalamus liang. It cannot be proven whether BS-0047 is a genuine ×Thyrsocalamus liang, too. Species identification will only be possible if all three plants can be found in this region and re-collected. It could also be found out whether ×Thyrsocalamus liang occurs wild in the region of the provinces of Phetchabun and Loei. A wild occurrence of ×Thyrsocalamus liang has not been known so far.