Cyclosorus aridus (D.Don) Ching

Family

Thelypteridaceae

Nomenclature

Cyclosorus aridus (D.Don) Ching, Bull. Fan Mem, Inst. Biol. 8: 194. 1938; Tardieu & C.Chr., Fl. Indo-Chine 7(2): 395. 1941; Holttum, Rev. Fl. Malaya ed. 1, 2: 259, f. 146. 1955 [‘1954’]; Holttum, Dansk Bot. Ark. 20: 22. 1961. – Aspidium aridum D.Don, Prodr. Fl. Nepal.: 4. 1825. – Nephrodium aridum (D.Don) J.Sm. in Hook., J. Bot. 4: 188. 1841; Bedd., Handb. Ferns Brit. India: 272, f. 139. 1883. – Thelypteris arida (D.Don) Morton, Amer. Fern J. 49: 113. 1959; K.Iwats., J. Jap. Bot. 38: 314. 1963; Tagawa & K.Iwats., SouthE. Asian Stud. 5: 68. 1967; Tagawa & K.Iwats., Fl. Thailand 3: 431. 1988. – Christella arida (D.Don) Holttum in B.K.Nayar & S.Kaur, Companion Handb. Ferns Brit. India: 206. 1974; Holttum, Kew Bull. 31: 320. 1976; Holttum, Fl. Males., Ser. II, Pterid. 1: 555, f. 1i. 1982 [‘1981’]; Boonkerd & Pollawatn, Pterid. Thailand: 219. 2000. – Type: Wallich, Nepal (not found at BM; possibly at BR, see Morton 1974, infra).

Description

Rhizome long creeping, about 3 mm diam.; scales pale brown, membranous, caducous, up to 5 by 1.5 mm. Stipes 13–68 cm long, scaly as well as hairy near base, bearing reduced pinnae on upper part, abruptly or gradually reduced. Laminae oblong-lanceolate, gradually narrowing downwards, acute at apex, 42–150 x 15–24 cm, pinnae 14–37 pairs; rachis densely hairy throughout; lower pinnae gradually narrowing downwards to mere auricles, middle pinnae larger, sessile, patent, linear-lanceolate, gradually narrowing towards long-acuminate apex, more or less auricled at base, 9.5–16 by 1.3–2.1 cm, lobed 1/3 way to costa; segments oblong-subdeltoid, acute to aciculate at apex, entire; chartaceous to coriaceous, pubescent on lower surface; veins pinnate, about 3 lower pairs uniting with those of the opposite groups, hairy as well as yellow-glandular. Sori medial; indusia small, thin, hairy, usually immersed among sporangia at maturity.

Distribution in Thailand

NORTHERN: Chiang Mai, Chiang Rai, Tak; PENINSULAR: Satun, Yala.

Wider Distribution

Himalaya to W Malesia, north to N Vietnam, Hong Kong and Taiwan.

Ecology

On clayey ground or in grassy fields in some open places at medium altitudes.

Similar species

Cyclosorus unitus (L.) Ching

Proposed IUCN Conservation Assessment

Least Concern (LC). This variety is widespread and not under any known threats.

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