Gigantochloa sp. (TH: S) 1
Gigantochloa sp.
Thai name: ไผ่ด่างกาญจนา (phai dang kanchana), "dang" = spot, blotch, "kanchana" = gold (or is just a short expression for the name of the province of Kanchanaburi).
Distribution: THAILAND (South), possibly native, in cultivation: A nursery in Kanchanaburi distributed plants under the name "Arundinaria suberecta, ไผ่ด่างกาญจนา (phai dang kanchana)" for many years, and a nursery in Nan distributed plants as "Dangkarnjana" (Facebook, 18 Apr. 2016). The suspected origin of this species is southern Thailand. — U.S.A.: Cultivated plants are known from Florida as "Bambusa suberecta" hort., and as "Jesse Durko Bamboo"; the origin of these plants is unrecorded, but assumed to have been introduced from Thailand. — PHILIPPINES: In cultivation, plants were introduced from Thailand.
Uses: Plants are used as garden ornamentals and for landscaping.
Comments: There is currently no evidence that all the specimens cited hereunder are conspecific.
Specimen: BS-0635 [C9] (living plant), Trang, southern Thailand, cult., received from ธ. ล. as "ไผ่ฝากด่าง (phai fak dang)", 21 Mar. 2011.
Gigantochloa sp. (BS-0635): Young shoot with culm-leaves, young culm, foliage-leaves, habit (from left to right)
Characteristics:
(1) Rhizome pachymorph. Culms straight, erect, slightly bending outwards, over 12 m tall by 6 cm in diameter. Young shoots emerge from July to September. Culm-internodes 25–30 cm long, mid-green, with pale yellow stripes of various widths on the lower culm and mid-culm, scattered with short pale or dark hairs, almost glabrous, smooth or minutely rough when old, 2–4 cm in diameter, thick-walled on the lower culm, moderately thick-walled on the mid-culm and upper culm. Culm-nodes not prominent, glabrous. Branches several, thin, relatively short, the central one slightly dominant; branching intravaginal or extravaginal; rebranching. Culm-leaves leathery, late deciduous, may remain loosely attached to the culm by extravaginal branching. Culm-leaf sheath broad parabolic, ca. 26–31 cm wide at the base and 20–26 cm high, rigid, brittle, light green striped on the pale yellow ground when fresh, scattered with short brown caducous hairs, light straw-colored when dry, shorter than half the length of the internode, margins eciliate? (entire with age), apex slightly convex-truncate. Culm-leaf auricles rim-like, about 3 cm wide and 2 mm high, entire, brown or blackish when fresh; bristles none. Culm-leaf ligule low (about 1 mm), entire or denticulate. Culm-leaf blade narrow triangular, about 1.6 cm wide at the base and 6 cm high, reflexed, early caducous, adaxially short brown hairy near the connection with the sheath, whitish with light green stripes when fresh, or the uppermost blades dark colored when fresh. Foliage-leaves 7–11 per branchlet. Foliage-leaf sheath pale or brown hispid. Foliage-leaf auricles inconspicuous; oral setae none. Foliage-leaf ligule short. Foliage-leaf blades 18–28 (32) × 1.5–2.5 (4.0) cm, green, with cream stripes of various widths, glabrous above, puberulous beneath; margins antrorsely scaberulous; base rounded to cuneate; apex attenuate; midrib slightly prominent; pseudopetiole 2–5 mm long. Flowers and seeds are unknown.
(2) Culm size dimensions: Basal culm not measured; lower culm 1.6 m above the ground, culm diameter 2.60 cm, wall thickness 0.65 cm, lacuna diameter 1.30 cm; mid-culm 4.0 m above the ground, diameter 2.50 cm, wall 0.30 cm, lacuna 1.90 cm; upper culm 7.2 m above the ground, diameter 0.95 cm, wall 0.10 cm, lacuna 0.75 cm; culm apex not measured.
Comments:
(1) The genus determination as a Bambusa remains doubtful. As the specimens have culm-leaves with low, rim-like auricles, they are probably members of Gigantochloa. There are some similarities with Gigantochloa balui but they are possibly not this species.
(2) The attempt to identify the species has so far been unsuccessful. A comparison of the culm-leaves and other characteristics among the specimens cited hereunder showed some similarities. The specimens were also compared with the following species, but their characteristics do not match sufficiently: Gigantochloa apus, Gigantochloa balui, Gigantochloa scortechinii, Gigantochloa wrayi.
The outline shape of the culm-leaf sheath of BS-0635 is typically broad parabolic
Specimen: BS-0434 [C4] (living plant), received from cultivated stock from the U.S.A. as "Bambusa suberecta, syn. Arundinaria suberecta", by C. T., 22 Jan. 2010.
Characteristics: Culms 6–7.5 m long by 2.5 cm in diameter, arching. — Otherwise as in BS-0635.
Images: Photos in BambooWeb.info [#1340].
Comments: (1) Flowers and seeds are unknown. — (2) The characteristics of BS-0434 [C4-R02] are very similar to those of BS-0635 [C9].
Specimen: BS-0885 [BBG] (living plant), received from cultivated stock from ต. น., NanBamboo, Nan Province, northern Thailand, as "Gigantochloa sp. Dang Parmar", 9 July 2016.
Characteristics: Habit unicaespitose, tight clump. Rhizome pachymorph, short. Culms straight, erect below, bending outwards above, 8 m tall [ultimate height not known]. Young shoots conical, culm-leaf blades spreading; emerge from July to August/September. Culm-internodes terete, ca. 25 cm long, with light green or yellowish-green to brownish-green stripes of different widths, initially thinly farinose, with white fuzz, distally abundant and dense, becoming scabrous with age; diameter 2.5 cm [ultimate diameter not known]; walls thick. Culm-nodes glabrous, smooth, not prominent; nodal line horizontal; nodal line and sheath scar not protruding; supranodal line obscure, ca. 10 mm above the nodal line; aerial roots none. Branch-buds solitary, subrotund, from the basal node up, occasionally from the first to the second node without a bud. Branches several, slender, subequal, the central one somewhat dominant, relatively short, upright; branchless on the basal and lower culm; branching intravaginal or rarely extravaginal; rebranching. Culm-leaves deciduous. Culm-leaf sheaths much shorter than the internode, about 1-third of the internode length, broadly parabolic, 9 cm wide at the base, 11 cm long, rigid, with cream to light green stripes, initially thinly farinose and scattered with appressed white fuzzy hairs, light straw-colored and with some darker stripes when dry; margins eciliate; apex rounded. Culm-leaf auricles low rims, extending from the blade base towards but not reaching the sheath margins, long-ovate at their ends, glabrous, erect; margins entire, without bristles, but occasionally with a few erect pale bristles at the ends. Culm-leaf ligule a few mm high, the margin denticulate with more or less erect long white fringes or bristles. Culm-leaf blade horizontally patent to reflexed, twisted when dry, early or late caducous, lanceolate, adaxially densely hairy near the base, the hairs light brown and antrorsely strigose. Foliage-leaves (5) 7–8 (10) per branchlet. Foliage-leaf sheaths rounded, white hispid, light green to orange-green when young, light straw-colored when dry. Foliage-leaf auricles very small, more or less rounded, margins entire. Foliage-leaf ligule 1–2 mm long, margin with several long erect whitish bristles. Foliage-leaf blades soft, lanceolate, (9) 17 (21) × (1.0) 2.5 (3.2) cm; mid-green with stripes in white of different widths, some entirely white, upper surface glabrous, lower surface glaucous, puberulent; base rounded to cuneate; apex acuminate to attenuate; margins antrorsely scabrous; midvein proximally distinct on both surfaces; pseudopetiole short, 1–2 mm long. Flowers are known, seeds are unknown.
Flowering and seeding: Sporadic flowering was observed in 2017/2018 (Dec. – Apr.), in 2019 (from May), and in 2020 (March-June). Seeds could not be detected. Flowering did not harm the vegetative growth of the plant.
Comments: The characteristics of BS-0885 [former C3, now BBG] are very similar to those of BS-0635 [C9].
Specimens: BS-0601 [BBG, SSG] (living plants), Thailand, without precise locality, plant with striped culms and leaves, from cultivation in Kanchanaburi Province, received as "ไผ่ลาย (phai lai)" from ธ. ล., 1 Dec. 2010, one plant started gregarious flowering in Apr. 2012, produced fertile seeds (→ BS-0601A) in Sep. 2012, and died in 2013.
Gigantochloa sp. (BS-0601): Foliage-leaves (left); young culm with culm-leaf (right)
Characteristics: The specimen BS-0601 went undescribed as the plant was at a young growth stage at the time of its introduction, and was transferred to Boonthammee Bamboo Garden soon after. However, a single plant raised from seeds (specimen BS-0601A) in 2012 is still in cultivation at Bambusetum Baan Sammi. It has since grown sufficiently tall for observation of its characteristics, and a detailed description was done on 3 Sep. 2023 (see below).
Seed viability: Unknown, viability is assumed to last at least a few months.
Seed weight: 0.3 g ≈ 6 dried spikelets (husk-wrapped seeds).
Seed germination: Seeds were collected from one cultivated, immature plant; a total of only about 30 seeds were collected, and about 20 seeds were sown out, of which only about 10 germinated. A single seed collected in Oct. 2012 was laid on moistened tissue paper, on 27 Oct. 2012, temperatures were not recorded, atmospheric humidity >70%, and the shoot emerged after 28(!) days. A further seed collected in Dec. 2012 was laid on moistened tissue paper, on 4 Dec. 2012, the shoot emerged after 64(!) days. Further seeds collected thereafter during the hot season in 2013 also resulted in rather late germination of more than one month and less than two months. From all the germinated seeds, a total of 5 seedlings survived. The flowering mother plant has beautifully striped leaves, whereas the seedlings, as expected, don't have stripes.
Flowering: A single, immature plant (BS-0601) started gregarious flowering in Apr. 2012 and died in mid-2013. Most spikelets turned out to be empty.
Comments:
(1) This is a species of the genus Gigantochloa, but the species has not yet been identified.
(2) BS-0601 and its descendant, BS-0601A [C2], are very similar to BS-0885, so I now (Sep. 2023) assume that they could well be conspecific. This similarity was revealed when BS-0601A grew taller with age. The current differences between these specimens may be confined to only two characteristics, but this may be only a temporary difference. BS-0885 has more than twice the culm height of BS-0601A, but the latter has been grown as a seedling and might not yet have reached its ultimate size in height and diameter. The other difference is that no bristles have been detected in the auricles of BS-0885, both the culm-leaf and foliage-leaf. Perhaps bristles may develop but are early caducous. In BS-0601A, it has been observed that bristles develop and are conspicuous, but they might occasionally not fully develop or drop off early.
Specimens: BS-0601A [C2] (living plant), raised from seeds of BS-0601 at Bambusetum Baan Sammi, a low quantity of seeds collected by D. O., from 20 Sep. 2012 to July 2013; from the only flowering plant, all seedlings developed green culms and leaves (without any variegation).
Gigantochloa sp. (BS-0601A): seeds (top left), germinating seed, 29th day (top right), seedling, several months old (bottom)
Gigantochloa sp. (BS-0601A): A 7-year-old seedling; all the seedlings have not developed any striping on the culms and leaves
Characteristics: Habit unicaespitose, a dense clump. Rhizome pachymorph, short. Culms straight, erect, bending outwards above and arching, ca. 5 m long [ultimate size possibly somewhat longer]. Young shoots conical, yellowish green, scattered with appressed very short dark hairs; sheath margins eciliate; culm-leaf blades spreading, green; emerge from May to September. Culm-internodes terete, 23–33 cm long, mid-green to dark green, glabrous, almost glossy when young, proximally smooth, distally minutely pruinose; diameter (1.5) 2–3 cm; walls very thick, solid on the basal culm, wall width as wide as the lacuna diameter on the lower culm (e.g., culm diameter 2.4 cm, wall width 0.8 cm, lacuna diameter 0.8 cm); lacuna without pith. Culm-nodes glabrous, smooth, not or slightly prominent; nodal line horizontal, dipping slightly below the bud; sheath scar dull black when young, marginally protruding 0.5 mm, with a narrow, slightly farinose transverse band just below the sheath scar when young; supranodal line obscure or irrecognizable, without a ridge; aerial roots none. Branch-buds solitary, ovate, two times broader than tall, from the basal node up. Branches several, unequal, the central one dominant, with 2 side branches subdominant, and a few smaller branches, long, initially upright; branching from the mid-culm up, the basal and lower culm usually unbranched; branching intravaginal. Culm-leaves early or late deciduous. Culm-leaf sheaths parabolic, ca. 12 cm wide at the base, to about 22 cm long, about 2/3 as long as the internode on the lower culm, leathery, light green when young, straw-colored when dry, more or less scattered with appressed very short dark hairs; apex horizontally truncate, symmetrical; margins eciliate. Culm-leaf auricles rim-like, brownish to blackish when young, each auricle equal in shape and size, and adnate to and contiguous with the basal margin of the blade as a slightly bent rim of low height (ca. 1–1.5 mm), and extending to the sheath margin by constantly increasing its height to 3–4 mm, thus forming an upright or slightly outward-bent triangular or obovate lobe; the rim margin entire, without bristles, the lobe margin entire but with erect pale bristles to about 5 mm long. Culm-leaf ligule very low, 1–1.5 mm high, dull blackish when young; the margin denticulate, with a few to several erect, early caducous pale bristles up to about 2 mm long. Culm-leaf blades leathery, reflexed to strongly reflexed, persistent or late caducous, narrowly lanceolate or long narrowly triangular; the base 1.3 cm wide, constricted to 0.7 cm at the junction with the sheath apex; adaxially with appressed very short hairs near the base, abaxially glabrous; light green when young, straw-colored when dry; apex sharp-pointed; margins scabrous, distally incurved. Foliage-leaves 7–11 per branchlet. Foliage-leaf sheaths light green when young, scabrous or pale hirsute; margins eciliate. Foliage-leaf auricles are low rims, raised to lobes towards the ends, green, the margin of the ends with several slightly undulated erect pale bristles to ca. 8 mm long. Foliage-leaf ligule inconspicuous, low, ca. 0.5–1 mm high; margin subentire; outer ligule inconspicuous or none. Foliage-leaf blades soft, lanceolate, 13–23 (27) × 1.6–2.6 (3.2) cm, glabrous above, puberulent beneath, medium to dark green above, medium green to bluish-green beneath; base rounded to wedge-shaped; apex attenuate; margins antrorsely scabrous; midvein proximally prominent, light green beneath; pseudopetiole short, 1–2 mm long.
Gigantochloa sp. (BS-0601A): A section of a young culm-internode, showing a culm-leaf with blade, ligule, and auricles; upper part of a dried culm-leaf, showing blade, ligule, and auricles in abaxial view; culms of various ages, a young culm in the foreground; habit of the plant, 11 years old (from left to right)