Thyrsostachys siamensis

Thyrsostachys siamensis Gamble

Thyrsostachys siamensis: Apex of a culm-leaf in a young culm, showing an erect
triangular blade, and an about 1.5–2 cm high convex-rounded junction of the sheath with
the blade (left, BS-0054_W4_042a); glabrous glossy mid-green internode with a
white dried culm-leaf in a young culm (center, BS-0054_W4_036a); habit of lower
part of young culms in an immature clump (right, BS-0054_W4_043)


  • Synonyms: Bambusa regia Thomson ex Munro; Thyrso­stachys regia (Munro) Bennet.
  • Thai names: ไผ่รวก (phai ruak) (Central); ไผ่ฮวก (phai huak) (Northern); ตีโย (ti yo) (Central); ว่าบอบอ (wa-bo-bo), แวบ้าง (wae-bang), แวปั่ง (wae-pang) (Karen-Mae Hong Son); สะลอม (sa-lom) (Shan-Mae Hong Son); Ref.: dnp.go.th/botany.
  • English names: Monastery Bamboo, Thailand Bamboo.
  • Distribution: THAILAND: throughout, native, wild and cultivated; in deciduous dipterocarp forest and mixed deciduous forest; MYANMAR: wild and cultivated; CHINA (Yunnan): wild and cultivated; VIETNAM. Introduced and cultivated in many countries of tropical and subtropical Asia.
  • Local distribution: Wild and naturalized in the Chiang Mai area, frequently planted.
  • Culm size: max. 13 m height, max. 6 cm diameter.
  • Descriptions:
    (1) "A very graceful, cæspitose deciduous bamboo. Culms 25 to 40 ft. [7.6–12.2 m] high, straight, not branching till high up, 1·5 to 3 [sic!] in. [3.8–7.6 cm] in diameter, usually covered with the persistent old culm-sheaths, otherwise greyish-green; nodes not prominent; internodes 8 to 11 in. [20–28 cm] long, with a white ring below the nodes. Culm-sheaths 9 to 11 in. [23–28 cm] long, 4·5 to 8 in. [11–20 cm] broad, soft, thin, covered with fine white appressed pubescence on the back, striate, attenuate upwards to a wavy truncate top, about 1·5 in. [3.8 cm] broad, produced at the margins into short triangular auricles; imperfect blade 4 to 5 in. [10–13 cm] long, narrowly triangular, the edges recurved; ligule narrow, ·1 in. [2.5 mm] broad, glabrous, finely ciliate. Leaves narrow, linear, 3 to 6 in. [7.6–15 cm] long, ·3 to ·5 in. [0.7–1.3 cm] broad, rounded or attenuate at the base into a very short (·05 in. [1.3 mm] long) petiole; points short, twisted; glabrous on both sides, or slightly pubescent beneath when young; scabrous on one edge; main vein narrow, secondary veins 3 to 5, intermediate 6 to 7; leaf-sheaths striate, white pubescent and ciliate, truncate, and ending in a glabrous callus; ligule very short, ciliate; branches after flowering often producing tufts of wiry branchlets, with very small leaves. [flowers described] ... It is easily distinguished from T. Oliveri by its much smaller size in almost all respects. ..." — J. S. Gamble, Bambuseae Brit. India, 1896, p. 59-60 [#1230].
    (2) "Densely tufted, sympodial bamboo. Culm erect or with arching tips, 8–14 m tall, 2–7.5 cm in diameter, wall very thick, solid in lower part, smooth, greyish-green, usually covered with persistent old culm sheaths; internodes 15–30 cm long, bearing a white ring below the nodes; nodes not swollen. Branches arising from midculm nodes upwards, with many branches at each node of which the primary one dominant. Culm sheath 20–25 cm long, 10–20 cm wide near the base, narrowing up to 2.5 cm wide at the apex, persistent, pale to purplish-green turning stramineous and thin with age, covered with scattered, pale appressed hairs; blade narrowly lanceolate, 6–15 cm × 5–12 mm, erect, pubescent adaxially; ligule very short, shortly laciniate; auricles absent or very small. Young shoots pale to purplish-green. Leaf blade narrow, linear, 7–14 cm × 5–8 mm, pale green, usually glabrous; sheath striate, white hairy along the margins; ligule very short, entire; auricles absent or very short. Inflorescences borne terminally on leafy or leafless branches, consisting of a main branch and many thin branchlets bearing bracteate clusters of few pseudospikelets; spikelet about 17 mm long, comprising 1 empty glume, usualy 2 perfect florets and a rachilla extension bearing a rudimentary floret. Caryopsis cylindrical, about 5 mm × 2.5 mm, surmounted by a yellowish, glabrous, soft, long beak." — S. Duriyaprapan & P. C. M. Jansen in S. Dransfield & E. A. Widjaja (editors), Plant Resources of South-East Asia No. 7, Bamboos, 1995: p. 145-147, fig. [#1226].
    (3) "Culms to 12 m, to 6 cm in diam.; internodes initially green, becoming gray-green, 20–30 cm; wall thick; nodes slightly thickened, with a white ring below. Branches several, main mid-culm ones to 1 cm in diam. Culm sheaths pale brown, 3/4–1 × as long as internodes, papery, appressed pubescent, margins ciliate, apex truncate; ciliate; auricles small; ligule ca. 1 mm; blade erect, base ca. 3/4 width of sheath apex. Leaf sheaths white pubescent and ciliate; ligule very short, pubes-cent; blade linear, 7.5–15 × 0.7–1.2 cm. Pseudospikelets 1.2–1.4 cm; prophylls to 0.8 cm; gemmiferous bracts 2 or 3; glumes 2 or 3; fertile florets 1–3. Fertile lemma 1–1.3 cm; palea slightly longer than lemma, narrow, bifid for 1/3 of its length; lodicules absent to 3. Anthers pale yellow, apex purple, apiculate. Ovary ovoid to turbinate; style 1, ca. 1.2 cm; stigmas 1–3. Caryopsis ca. 0.6 cm. 2n = 76*." — Flora of China.
    (4) Kew GrassBase. (5) INBAR. (6) Flora of Taiwan.

  • Line drawing of
    culm-leaf sheath apex of
    Thyrsostachys siamensis,
    from  J. S. Gamble, Bambuseae
    Brit. India, 1896, pl. 51.


  • Characters (distinguishing characters between Thyrsostachys oliveri and T. siamensis): See under Thyrsostachys oliveri.
  • Images: Line drawing in Flora of China; Flora of Taiwan. Photos in AsianFlora (habit, culms); photo of type of Bambusa regia at Kew Herb. (culm sheath, leafy branch); R. Pattanavibool in A. N. Rao & V. Ramanatha Rao (ed.), 1998: fig. 9 (seeds) [#1211].
  • Characters: Rhizomes pachy­morph, short-necked, forming a very tight clump. Young shoots emerging from early or mid June. Culms stiffly erect on lower and middle part, slightly bending above from weight of foliage, unbranched on lower part. Internodes mid-green to dark-green, glabrous, glossy, or initially thinly covered with white fuzz, yellowish green to brown when old; thick-walled, basal internodes solid. Nodes not prominent; sheath-scar ring black when young, soon fading to light grey. Culm-leaves of lower culm persistent, decaying while attached to the culm; upper culm-leaves (where branches develop) deciduous; lower culm-leaves longer than internode, upper culm-leaves shorter; culm-leaves green, lower ones reddish-green when young, soon drying to straw color, light grey or almost white color, covered with whitish fuzz when young, glabrous soon after; culm-leaf sheath apex convex-truncate; culm-leaf ligule very short, convex, entire; culm-leaf auricles none or inconspicuous, bristles none; culm-leaf blade typically reflexed in young culm, lower culm-leaf blade soon deciduous from sheath. Branching intravaginal; several branches develop from a single bud; branches subequal, one slightly dominant. Foliage leaves long and narrow, dark green; twig usually with 8 leaves of varying sizes, the largest about 15 (18) cm long and 9 (11) mm wide, glabrous on both sides; leaf sheath ligule inconspicuous, auricles and bristles none. — based on specimens cited below.
  • Uses: Shoots for food, culms for construction, plants for hedges, screening and wind-break. One of the most useful species.
  • Cultivation requirements: Easy growing, thrives well in heavy (loamy, clay) moisture-retentive soil with good drainage, but can grow even in poor and dry soil. It prefers partial shade, but grows well in full sun if the soil does not dry out, and it tolerates full shade, too.
  • Comments: Diameter of culms in the description by Gamble (1896): "... 1·5 to 3 in. [3.8–7.6 cm] in diameter ..." This is certainly an error. If the growth height of Thyrso­stachys siamensis is less than that of T. oliveri, as Gamble notes, the diameter of T. siamensis can not be greater than that of T. oliveri.

Thyrsostachys siamensis seeds,
coll. in Kanchanaburi, Mar. 1997 —
Photo by R. Pattanavibool in
 A. N. Rao & V. Ramanatha Rao (ed.),
1998: fig. 9 [#1211]


  • Specimens: BS-0308 [S6x] (living plant), raised from seeds, seeds distributed as "Thyrsostachys siamensis" by the Royal Forest Department at VIII World Bamboo Congress, Bangkok, 16–18 Sep. 2009, seeds received from B. C., 8 Oct. 2009.
  • Characters: Some culm-leaf sheaths when young may develop a pattern of irregular, brownish to blackish blotches, which is fading with age.
  • Flowering and seeding: Compilation of Bamboo Seeds: BS-0308.
  • Comments: (1) Possibly true Thyrsostachys siamensis. (2) The seedlings suffered from too long waterlogging during rainy season in 2017, and their recovering is at risk.
  • Specimens: BS-0165 [E4] (living plant), raised from seeds received as "Thyrsostachys siamensis" from A. L., southern Thailand, 28 June 2014.
  • Flowering and seeding: Compilation of Bamboo Seeds: BS-0165.
  • Comments: Possibly true Thyrsostachys siamensis. The plant raised from seed is not yet mature, hence ultimate culm height and diameter is not known.

      Chumphon (ชุมพร)
  • Culm size: Not recorded, assumed to reach a tall height with maturity.
  •  
  • Specimens: BS-0569 [E4] [W4x] (living plants), ต. หาดพันไกร (Hat Phankrai Subdistrict), อ. เมือง Mueang District, Chumphon Province ["Phetchaburi", in err.], northern South Thailand, coll. C. S. #3073, 4 June 2010, received Dec. 2010.

  • Thyrsostachys siamensis cl. Chumphon (BS-0569):
    The junction of the culm-leaf blade with the
    culm-leaf sheath forming a high convex arc
    like a steep Gaussian bell curve.


  • Characters: This clone has an unusual broad variation in the shape of the apex of the culm-leaf sheath. In some culm-leaves, the section with the junction of the culm-leaf blade shows a very steep Gaussian bell curve. In other culm-leaves of the same plant, the line of junction is almost horizontal (as described and pictured in Thyrsostachys oliveri by Gamble, 1896). Any variation between these two extremes may occur on the same plant. Usually, the culm-leaf blade is stiffly erect in this clone, but can occasionally be reflexed. No significant differences in other characters could be found.
  • Comments: Three plants of this clone were obtained, of which one plant started flowering in early Feb. 2012. This flowering was restricted to a single tall culm (unbranched from base to about 5 m), flowering ended about Mar. 2013 and that single culm was going to die, whereas all the other culms remained alive, and a thick new shoot from the rhizome developed soon thereafter. Not a single seed was found, and no seedling on the ground. In November 2013, another culm started sporadic flowering, the flowers fully developed by mid-February 2014. Neither seeds nor seedlings were found. The plant continued vegetative growth since (15 Aug. 2018).

      Phetchabun (เพชรบูรณ์)
  • Specimens: BS-0054 [W4], BS-0054-1 [BBG] (living plants), seedlings received as "ไผ่สร้างไพร" (phai sang phrai) from the Royal Project, Huai Hong Khrai (ห้วยฮ่องไคร้) Study Center, A. Doi Saket, Chiang Mai Province, Nov. 2011, grown from seed collected from flowering wild plants in Petchabun (เพชรบูรณ์), north-eastern Central Thailand.
  • Characters: Very similar to BS-0569, especially the very steep convex line of junction of blade base and sheath apex. Ultimate culm height and diameter not yet known.
  • Comments: When having received the plants as "ไผ่สร้างไพร" (phai sang phrai), a name that is usually attributed to Bambusa nana hort., it was said that mature plants look similar to phai liang, also a name of Bambusa nana hort., but would grow taller in culm height and bigger in diameter than phai liang. By June 2015, however, it became apparent that the culm-leaves look more like a species of Thyrsostachys, and by July 2017 it became clear that the plants are certainly not Bambusa nana hort, phai liang, but most likely Thyrsostachys siamensis (Sep. 2017, Aug. 2018).

Thyrsostachys siamensis 'Sweet Siamese' (สวีธสยามอีส)
  • Thai names: ไผ่รวกหวาน (phai ruak wan), ไผ่รวกหน่อหวาน (phai ruak no wan); "no" = shoot, sprout; "wan" = sweet.
  • Distribution: Thailand, cultivated.
  • Culm size: Height 5 - 10 m, diameter ca. 3 - 4 cm.
  • Images: Post and photos by สวนไผ่บงหวาน เพชรน้ำผึ้ง (suan phai bong wan, phet nam phueng) in facebook, 29 Mar. 2014; post and photos by Niramit Sareerudt in facebook, 13 Feb. 2014; post and photos by ชมรมคนรักไผ่ แห่งประเทศไทย (Thai Bamboo Lovers' Club) in facebook, 19 Jan. 2014.
  • Specimens: No specimens collected.
  • Uses: Planted for shoot production; shoots are very tasteful and sweet, and can even be eaten raw.

Thyrsostachys siamensis 'Wealthy Siamese' (เวลธีสยามอีส)
  • Thai name: ไผ่รวกเศรษฐี (phai ruak setthi); "setthi" = millionaire, rich, wealthy.
  • Distribution: Thailand, cultivated.
  • Culm size: Height not recorded, diameter ca. 4 cm.
  • Images: Post and photos by Nanbamboo น่านแบมบู in facebook, 6 Feb. 2014.
  •  
  • Specimens: BS-0149 [BBG] (living plant), Nan Province, 7 Mar. 2014.
  • Characters: Culm internodes striped in pale yellow and yellowish green.
  • Uses: Plants as a garden ornamental.

Thyrsostachys siamensis 'Arunee Black' (อรุณีดำ)
  • Distribution: Thailand, cultivated.
  • Characters: Internodes dark green to blackish.
  • Images: Post and photos by Thoop Nakasen (Nanbamboo น่านแบมบู) in facebook, 4 Dec. 2017.
  • Uses: Plants as a garden ornamental.
  • Comments: (1) Clone raised from seeds by Nanbamboo, Nan, northern Thailand, between 2010 and 2016. (2) อรุณี (Aruni), or transcribed as "Arunee" to please the English language orthography and pronunciation, is a Thai first name for female persons.