Dendrocalamus hirtellus

Dendrocalamus hirtellus (BS-0550): Young shoot, thickly covered with white wax, culm-leaf blades peach-colored (left), the upper part of a young culm-leaf (center), culm-node, flat and glabrous, the culm-leaf above the node is covered with white wax throughout and soft white waxy hairs on the base, and below the node is a narrow white waxy ring, both wax and hairs are easily removable, as demonstrated in the photo by two small cleared spots (right)

• • Specimen: BS-0550 [E5] (living plant), near อุทยานแห่งชาติ เขาน้ำค้าง (Khao Nam Khang National Park), Songkhla Province, southern Thailand, coll. by C. S., #3052, 30 May 2010.

  • Characteristics: Habit moderately tight caespitose, tall and scrambling above. Rhizome pachymorph [n.v.]. Culms straight, erect for 10 m or longer, then arching above and scrambling, ultimate length and diameter not yet known (over 12 m long with a basal diameter of 4 cm in June 2021). Young shoots thickly white-waxy and with patches of reddish-brown hairs; emerge from May/June/July to November. Culm-internodes terete, 43–53 cm long, mid-green when young till mid-age, dull greenish to brownish when old, glabrous throughout, initially somewhat farinose; diameter increasing with height, gradually increasing from base to lower mid-culm up to 57% (e.g., basal diameter 3.5 cm, diameter 5.5 cm on the 8th internode at 3.3 m above the ground), then remaining constant for several meters and gradually decreasing towards the top; walls thick [not yet observed in detail]. Culm-nodes glabrous, flat; sheath scar marginally (1 mm) protruding; supranodal line obscure, without a ridge; with a narrow whitish farinose ring below the sheath scar when young, soon fading; occasionally with short aerial roots on the lowest or two lowest nodes. Branch-buds solitary, triangular-subrotund, present from the lowest node up. Branches few, initially 3, central one dominant but not very thick and much elongating, ascending and then widely arching and perpendicularly hanging down to the ground, or scrambling into nearby vegetation; rebranching; unbranched on the lowest 9–11 nodes (3–5 m from the ground); branching intravaginal. Culm-leaves deciduous. Culm-leaf sheaths 21–23 cm wide at the base, 18–22 cm long, shorter than half internode length; rigid; pale pinkish-orange to peach-colored and copiously covered with white wax when young; basal part with long white velvety waxy hairs; upper part with more or less reddish-brown hairs; wax and hairs easily removable, not persistent, surface almost glabrous and light orange-brown with age; outer overlapping margin 3–6 mm long irregularly pale ciliate, inner wrapped margin eciliate; apex rounded, with its middle part (about 3–4 cm wide) slightly convex-truncate. Culm-leaf auricles conspicuous somewhat waved and irregularly 1–4 mm high rims, higher toward the protruding ends, not extending the sheath margin, blackish when young, margin with few to several up to 23 mm long spreading and lasting pale bristles. Culm-leaf ligule membranous, base irregularly high, to ca. 5 mm, initially light green, soon changing to dark-colored when young, the base extending into pale irregular teeth, a few of them with very slender and short pale bristles; papery, deeply cleft, eciliate, and light straw-colored when dry. Culm-leaf blade coriaceous, caducous, horizontally patent, almost as long as the sheath, pale peach-colored on both surfaces when young, not green; lanceolate to broad-lanceolate; base rounded; apex long-pointed; junction with the sheath 10–12 mm wide, adaxially near the junction hairy, otherwise glabrous on both surfaces. Foliage-leaves 5–7 per branchlet. Foliage-leaf sheaths light green, glabrous or hispid, margins eciliate. Foliage-leaf auricles inconspicuous, with a few (1–3) slender straight pale bristles 3–6 mm long. Foliage-leaf ligule inconspicuous, very short, lower than 1 mm, subentire. Foliage-leaf blades soft, medium-sized, 16–26 × 2–2.7 cm, but can reach larger sizes (ca. 40 cm long by 5 cm wide, seen but not measured), lanceolate, green, glabrous above, pubescent beneath; base rounded to wedge-shaped; apex attenuate; one margin antrorsely scabrous, the other margin antrorsely scaberulous or smooth; midrib proximally slightly prominent and light green on both surfaces; pseudopetiole 2–4 mm long. — Flowers and seeds are unknown.

  • Uses: Not recorded. The species has ornamental value (e.g., for its heavy white-waxy culm leaves with peach-colored blades) and can be used for landscaping.

  • Cultivation requirements: Slowly growing under the Chiang Mai climate; in part shade, on heavy soil, moisture-retentive to moist with good drainage.

  • Provisional identification: BS-0550 is closest to Dendrocalamus hirtellus, but mainly differs from this species by its non-farinose or initially little farinose culm-internodes. Furthermore, in BS-0550, the culm-leaf sheaths are pinkish-orange or peach-colored throughout (hidden by a heavy white-wax cover), with no green parts when young, and the culm-leaf blades are horizontally patent and peach-colored throughout (with no green tint). A culm diameter that conspicuously increases with the culm height has also been observed in all culms of BS-0550. It is currently not clear if all these deviating characteristics are within the species range of Dendrocalamus hirtellus, or if BS-0550 is not conspecific. — Mu Chakkrapong, pers. comm., Facebook, 20–21 Oct. 2017.

  • Comments: (1) Propagules from clump division initially produce small culms. In BS-0550, such small culms are quite different in appearance from thick culms. In BS-0550, young shoots of small culms are usually dark green and without white wax, and culm-leaves may be persistent or late deciduous; culm-nodes are with a prominent ridge and a clearly marked nodal line. (2) When the clump gets larger and its culms have a bigger diameter (>4 cm), the internodes in young shoots develop some white wax, but this does not last long on the internodes. (3) A culm diameter that increases with the culm height between the base and lower mid-culm has also been observed in some other species (e.g., in the genera Dendrocalamus, Gigantochloa, Melocalamus, Schizostachyum) under cultivation at Baan Sammi: BS-0006, BS-0078, BS-0208, BS-0494, BS-0602, BS-0724. The diameter difference can be seen with the naked eye but is not as impressive as in BS-0550.