Volume 11 > Part 3 > Year 2013 > Page 371 > Arecaceae > Calamus

32. Calamus palustris Griff.wfo-0000758896

Calcutta J. Nat. Hist. 5: 60. 1845; Evans et al., A Field Guide to the Rattans of Lao PDR: 60. 2001.— Palmijuncus palustris (Griff.) Kuntze, Revis. Gen. Pl. 2: 733. 1891.

Accepted Name : This is currently accepted.

Synonyms & Citations :

Description : Moderate to robust clustering rattan. Stems climbing to 30 m long, without sheaths 0.3–3 cm diam., with sheaths 0.7–5 cm diam., internodes 15–30 cm long. Leaf cirrate; sheaths bright green, variably armed sparsely to densely with scattered, patent or slightly reflexed red-brown, yellow-based spines to 3 cm long, sometimes interspersed with much smaller broad-triangular dark spines, pale to reddish-brown caducous indumentum usually abundant on newly emerged sheaths, sometimes distinctly striped; knee conspicuous, usually more sparsely armed than the rest of the sheath; ocrea very inconspicuous, unarmed, soon disintegrating; flagellum absent; petiole 5–30 cm long, semi-circular in cross-section, the adaxial surface often armed with short erect spines; rachis to 2.5 m or more; cirrus 0.4–1 m; leaflets 10–25 on each side of the rachis arranged in evenly spaced divergent pairs, a few leaflets near the base and the cirrus borne singly, the largest leaflets to 35 by 5.5 cm, rarely larger, tips somewhat cucullate, margins bristly, veins both adaxially and abaxially unarmed. Inflorescences male to 1.4 m long, the female usually much shorter, to 50 cm long, lacking a terminal flagellum, the male branched to 3 orders, the female to 2 orders, partial inflorescences 8–12, close and not very well differentiated; male rachillae 2.5–5 by 0.3 cm long, female rachillae to 10 by 0.4 cm. Fruit rounded, the calyx explanate at fruit maturity so fruit appearing sessile, 0.7–1.2 by 0.7–1 cm, with a short rather triangular reddish beak to 0.15 by 0.15 cm, and covered in 17 vertical rows of white unchannelled scales. Seed ca 0.5–0.9 by 0.5–0.7 cm, ± rounded; endosperm homogeneous.

Thailand : NORTHERN: Mae Hong Son, Chiang Mai, Chiang Rai, Phrae, Tak; NORTH-EASTERN: Loei, Nong Khai; EASTERN: Chaiyaphum, Nakhon Ratchasima, Buri Ram; CENTRAL: Saraburi, Nakhon Nayok; SOUTH-EASTERN: Trat; PENINSULAR: Chumphon, Ranong, Krabi, Trang, Songkhla, Yala, Narathiwat.

Distribution : S China to Nicobar Islands, Myanmar (type) and Peninsular Malaysia.

Ecology : Alluvial soils in the lowlands.

Vernacular : Wai khring (หวายขริง)(Trang); wai ling (หวายลิง), wai pok (หวายป๊อก)(Narathiwat); sa-kro-ai (สะกรอไอ)(Malay-Narathiwat).

Uses: Handicrafts and edible shoot.

Conservation Status: Not threatened.

Notes: The delimitation of taxa within Thai members of the group of rattans related to Calamus palustris in Furtado’s section Phyllanthectus has proved to be extremely problematical, each recent author coming to different conclusions. Hodel & Vatcharakorn (1998) recorded Calamus palustris, C. latifolius, C. khasianus, C. kerrianus and C. loeiensis, of which the last had recently been described as new. Evans et al. (2002) regarded C. kerrianus and C. loeiensis as synonyms of C. palustris, and commented that they were unable to place with certainty the specimen on which Hodel & Vatcharakorn’s C. khasianus record is based. Evans et al. (2002) accepted the following Thai taxa: Calamus palustris (as var. cochinchinensis), C. nambariensis, and C. wailong; however, in treating primarily the species of Laos and northern Thailand, they did not consider Peninsular Thai species. In Henderson’s regional field guide (2009), only two taxa are recognized: C. palustris and C. nambariensis. Calamus kerrianus and C. loeiensis are included as synonyms of C. palustris, along with several other names of extra Thai species, including the earlier published C. latifolius, while in C. nambariensis he included C. khasianus and C. wailong. In the checklist of Thai Palms (Dransfield et al., 2004) the following taxa were recognized: C. khasianus, C. latifolius, C. nambariensis, C. palustris and C. palustris var. malaccensis and C. wailong; the first two were included based on the records in Hodel and Vatcharakorn.

Henderson’s account provides a relatively easy solution to the complex variation in this group, but, in that the two accepted taxa are strikingly variable, the two remaining accepted taxa are themselves still difficult to separate with confidence and perhaps the synonymy is too drastic. We prefer to follow the carefully argued conclusions of Evans et al. (2002) while accepting, like Henderson and Evans et al., that the whole group needs a thorough revision. Unfortunately the taxa are very difficult to identify with complete certainty if ripe fruits are unavailable. Furthermore variation within individual stems may be even greater than the variation between taxa (as demonstrated by Evans in a single stem of C. wailong). All this undermines confidence in the taxonomic treatment. We accept C. palustris, C. nambariensis and C. wailong in our account.

Hodel and Vatcharakorn recorded Calamus latifolius from Thailand based on the collection Hodel et al. 1760 from Kanchanaburi. Unfortunately, the specimen lacks the crucial details that would allow its identity to be confirmed. The specimen has leaf sheaths with spines that are much larger than is usual in C. palustris and indeed approaches material of C. latifolius. A final decision on its identity will have to wait for a complete revision of this difficult complex of species.