Chloothamnus elatus
Chloothamnus elatus (Holttum) Widjaja, Sandakania 22, 2016: 38.
Synonym: Nastus elatus Holttum, Kew Bull. 21 (2), 1967: 291.
Thai names: ไผ่รวกปาปัว (phai ruak papua); ไผ่โคลโอทำนุสเอลาทุส (phai khloothamnut elathut). — BKF [#1368].
English name: New Guinea Sweet Shoot Bamboo.
Distribution: THAILAND: introduced, in cultivation, rare. — PAPUA NEW GUINEA: throughout the highlands, common.
Culm size: Height 15–20 m, diameter 7.5–10 cm.
Description: "… Rhizomes short; pachymorph. Culms erect; 1500–2000 cm long; woody. Culm-internodes terete; 30–45 cm long. Lateral branches dendroid. Branch complement many. Culm-sheaths smooth. Culm-sheath ligule 1.5 mm high; ciliolate. Culm-sheath blade lanceolate; erect, or reflexed; 22 cm long; 42 mm wide. Leaves 5–6 per branch. Ligule an eciliate membrane. Leaf-blade base with a brief petiole-like connection to sheath. Leaf-blades linear; 8–16 cm long; 4–8 mm wide. Leaf-blade apex acuminate. … [flowers and seeds described]." — Kew GrassBase [#1335].
Images: Photos in YellowSeedBamboo (habit, culms, shoot); EarthCare (foliage); Quindembo (habit, culms, shoot).
Uses: Shoots for food, can be eaten raw; plants as garden ornamentals.
Cultivation requirements: Vigorously growing, in part shade to full sun, sandy loam, normal moisture-retentive with very good drainage. Does not tolerate waterlogged soil; does not grow well in pots.
Chloothamnus elatus (BS-0245): Apex of a culm-leaf in a young shoot, a few weeks old (left); apex of a culm-leaf in a young shoot, several months old (right)
Specimen: BS-0245 [S3] (living plants), received as "Nastus elatus" from cultivated stock from the USA in 2009.
Characteristics: Habit tight caespitose. Rhizome pachymorph, short-necked. Culms straight, over 10 m long [ultimate size not yet known], erect below, bending above, tips drooping. Young shoots light green, glabrous, covered with a white mealy deposit, appearing bluish; culm-leaf blades green, patent; emerge from May/June to September. Culm-internodes terete, 25–32 cm long on mid-culm, bright green when young, glabrous, initially farinose, dull mid-green with a bluish tint and smooth when old; diameter 5 cm [ultimate diameter not yet known]; thin-walled, easily splitting, lacuna with white pith on the basal culm, the pith not easily removable when old, lacuna without pith on the lower, mid, and upper culm (5th internode 85 cm above the ground, diameter 1.9 cm, wall thickness 2–2.5 mm). Culm-nodes glabrous, flat; nodal line horizontal; sheath scar marginally protruding; supranodal line clearly discernible; with a white ring below sheath scar; aerial roots none. Branch-buds solitary, small, margins initially densely pale ciliate, the first 2–3 (4) lowest nodes without a bud. Branches many, subequal, thin, 1–2 mm in diameter, from the mid-culm up; branching extravaginal, infravaginal, and intravaginal; branching initiates from the mid-culm upwards; rebranching. Culm-leaves deciduous. Culm-leaf sheaths 8–12 cm wide at the base, 14–16 cm long, half as long as the internode, or a little longer, rigid, light green to greenish-yellow, and copiously covered with a white mealy deposit when young, yellowish green, smooth and almost glossy with age, dull yellowish straw-colored with dark spots when dry; margins eciliate; apex rounded. Culm-leaf auricles inconspicuous or none, without bristles. Culm-leaf ligule inconspicuous, ca. 1 mm high, entire, eciliate. Culm-leaf blades rigid, caducous, deflexed to reflexed, linear to broad-linear to lanceolate, 1.5–2 cm wide at the junction with the sheath, 6–10 cm long, green when young, straw-colored when dry. Foliage-leaves (7) 11–15 per branchlet. Foliage-leaf sheaths green, glabrous. Foliage-leaf auricles inconspicuous or none, without bristles. Foliage-leaf ligule very short, entire, eciliate. Foliage-leaf blades soft, (11) 17 (19) × (0.8) 1.1 (1.3) cm, linear, mid-green to light green, glabrous above, finely pubescent beneath; base rounded to wedge-shaped; apex long-acuminate; margins antrorsely scaberulous; midrib not prominent; pseudopetiole short, 0.5–1 mm long.
Comments:
(1) Vegetative propagation by plant division is known to be difficult and not always successful in this species. A test on propagation was carried out with a 7-year-old clump in mid-2017. As a preparation, several medium-sized culms were trimmed: Some culms were trimmed down to leave about 4 dormant buds on the culm without branches and leaves; other culms were trimmed down to a single and lowest branched node, with 2–4 lower nodes each bearing a dormant bud. All the unbranched culms withered and died, and about 60% of the branched culms survived.
(2) One plant started sporadic flowering in May 2020: The leafy tip of a single culm of BS-0245 developed a terminal inflorescence. Nevertheless, the plant had since produced strong young shoots from the rhizome.
(3) Until September 2020, no seeds were found in the flowers, and no seedlings had developed. Although BS-0245 did not develop from sporadic to gregarious flowering, all culms gradually withered, and by 2022 the plant was dead including the rhizomes from which no new shoots developed in 2023.
(4) An investigation at Tropical Bamboo, Florida, USA, showed that no flowers had developed in all of their cultivated plants of Chloothamnus elatus in May 2020 (R. S., pers. comm., Facebook, 22 May 2020).
Chloothamnus elatus (BS-0245): Leafy branch with a terminal inflorescence
Chloothamnus elatus (BS-0245): A flowering branch in an early stage of development
Chloothamnus elatus (BS-0245): A flowering branch in an early stage of development