Lygodium japonicum (Thunb.) Sw.
Lygodium japonicum (Thunb.) Sw., Schrad. J. Bot. 1800(2): 106. 1801; Bedd., Handb. Ferns Brit. India: 457. 1883; C.Chr., Contr. U.S. Natn. Herb. 26: 329. 1931; Tardieu & C.Chr., Fl. Indo-Chine 7(2): 37. 1939; Holttum, Fl. Males., Ser. II, Pterid. 1: 51, f. 8d–f. 1959; Ching, Fl. Reipubl. Popularis Sin. 2: 113, pl. 8, f. 1–4. 1959; Tagawa & K. Iwats, SouthE. Asian Stud. 5: 34. 1967; Tagawa & K.Iwats., Fl. Thailand 3: 61. 1979; Boonkerd & Pollawatn, Pterid. Thailand: 82. 2000; Newman et al., Checkl. Vasc. Pl. Lao PDR: 28. 2007. – Ophiglossum japonicum Thunb., Fl. Jap.: 328. 1784.
Lygodium microstachyum Desv., Berl. Mag. 5: 308. 1811; Ching, Fl. Reipubl. Popularis Sin. 2: 112, pl. 8, f. 5–8. 1959; Newman et al., Checkl. Vasc. Fl. Lao PDR: 28. 2007. – Lygodium japonicum var. microstachyum (Desv.) Tardieu & C.Chr., Fl. Indo-Chine 7(2): 38. 1939.
Lygodium flexuosum auct. non (L.) Sw.: Holttum, Dansk Bot. Ark. 20: 15. 1961, p.p.
Rhizome creeping, densely covered with blackish brown hairs. Fronds climbing; stipes up to 30 cm, stramineous, densely pubescent near the base, sparsely hairy upwards about 1.5 mm diam., very narrowly winged except the very base; hairs at base of stipes brown, downy; rachis like the upper part of stipes, rather densely hairy on the upper side; pinnae numerous, less than 10 cm apart; primary rachis-branches distinct, (1–)3–15 mm long, densely hairy, the apex dormant but occasionally protruding; secondary rachis-branches up to 20 cm long, densely hairy on the upper and very sparsely so on the lower sides, distinctly winged throughout; the two main branches of large fronds bipinnate, deltoid to suborbicular in outline; tertiary leaflets of lower rachis-branches palmate with 5–7 lobes, the middle lobe longer, tertiary leaflets of higher parts trilobed or hastate, the lobes actually biserrate at margin, obtuse to subacute at apex; stalks of leaflets to 3 mm long, without articulation, with distinct wings; costae winged throughout, hairy; veins on both surfaces hairy with long downy pale brownish hairs. Sporangia-bearing lobes protruding at margin of the lobes of tertiary leaflets which are usually smaller than those without sporangia, 3–8 (–12) mm long, about 1.5 mm broad; indusia hairy at margin .
Distribution in Thailand
NORTHERN: Chiang Mai, Tak; NORTH-EASTERN: Loei; SOUTH-WESTERN: Kanchanaburi, Phetchaburi, Prachuap Khiri Khan.
Distribution in Laos
Hua Phan, Luang Phrabang, Xieng Khouang.
Sri Lanka, Himalaya to China north to Chekiang, Korea, Japan, Indochina, throughout Malesia east to New Guinea; also naturalized in the United States.
On dry open grass fields or on mountain slopes in deciduous forest at low or medium altitudes.
Proposed IUCN Conservation Assessment
Least Concern (LC). This species is widespread and not under any known threat.
This is a very variable species. In comparison with the typical Japanese form, Thai plants are smaller (seldom 1 m high), have shorter rhizome (at least when growing on dry rocky slopes), and have a denser indumentum, especially when growing in dry situations. Such plants are rather difficult to distinguish from Lygodium flexuosum , especially its smaller form . Dy Phon (2000) records Lygodium japonicum for Cambodia but we have been unable to verify this.
Voucher specimens - Thailand
Murata et al. T-16800, Tak, Doi Car (P).
Voucher specimens - Laos
Poilane 2001, Hua Phan (P).
Voucher specimens - Cambodia
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