Family

Ophioglossaceae

Nomenclature

Helminthostachys zeylanica (L.) Hook., Gen. Fil: t. 47b. 1840; Bedd., Handb. Ferns Brit. India: 467, f. 292. 1883; E.Smith, J. Siam. Soc. Nat. Hist. Suppl. 8: 9. 1929; Clausen, Mem. Torrey Bot. Club 19(2): 108, f. 20. 1938; Tardieu & C.Chr., Fl. Indo-Chine 7(2): 10, f. 1.1 & 1.2. 1939; Holttum, Rev. Fl. Malaya ed. 1, 2: 42, f. 2. 1955 [‘1954’]; Seidenf., Nat. Hist. Bull. Siam Soc. 19: 85. 1958; Ching, Fl. Reipubl. Popularis Sin. 2: 26, pl. 1, f. 7 & 8. 1959; Tagawa & K.Iwats., SouthE. Asian Stud. 5: 32. 1967; Tagawa & K.Iwats., Fl. Thailand 3: 38. 1979; Boonkerd & Pollawatn, Pterid. Thailand: 23, 65. 2000; Newman et al., Checkl. Vasc. Pl. Lao PDR: 29. 2007. – Osmunda zeylanica L., Sp. Pl. 1063. 1753.

Description

Rhizome creeping, up to 7 mm in diameter, bearing the numerous fleshy roots and a frond in each year. Phyllomophore 20–40 cm long, fleshy, green or purplish brown; trophophyll up to 20 cm long, 30 cm wide, tripartite, each with a terminal lobe and one or two pairs of sessile lateral lobes, rachis winged; lobe oblong to oblong-lanceolate, round to acute at apex, cuneate and more or less decurrent at base, up to 20 cm long, 5 cm broad; veinlets once or twice forked, all free; texture softly herbaceous. Sporophyll with stalks up to 15 cm in length, placed at base of tripartite trophophyll, spikes up to 20 cm long; with numerous short branches bearing round sessile sporangia .

Distribution in Thailand

NORTHERN: Chiang Mai, Chiang Rai, Lampang; NORTH-EASTERN: Loei; SOUTH-WESTERN: Kanchanaburi; SOUTH-EASTERN: Chanthaburi; PENINSULAR: Ranong, Surat Thani, Phangnga, Nakhon Si Thammarat, Trang, Songkhla, Yala, Narathiwat.

Distribution in Laos

Attapeu, Champasak, Khammouane, Savannakhet, Vientiane.

Distribution in Cambodia

Kandal, Ratanakiri, Siem Riep.

Wider Distribution

Palaeotropics, from Sri Lanka and India (Assam) to New Caledonia and Queensland.

Ecology

Terrestrial on humus-rich slopes in light shade at low or medium altitudes.

Proposed IUCN Conservation Assessment

Least Concern (LC). This species is widespread and not under any known threat.

Voucher specimens - Thailand

Maxwell 86-803, Songkhla, Natawee (P); Larsen et al. 43028, Yala, Khao Yai, Jaha (P).

Voucher specimens - Laos

Maxwell 07-199, Savannakhet (CMU); Vidal 2309, Vientiane (P); Leong-Skornickova et al. 1829, Vientiane capital (E).

Voucher specimens - Cambodia

David et al. CL861, Ratanakiri, Norn Kabat forest (P).