Heterogonium alderwereltii Holttum

Family

Tectariaceae

Nomenclature

Heterogonium alderwereltii Holttum, Sarawak Mus. J. 5: 163. 1949; Holttum, Rev. Fl. Malaya ed. 1, 2: 522, f. 305. 1955 [‘1954’]; Holttum, Kalikasan 4: 229. 1975; Tagawa & K.Iwats., Fl. Thailand 3: 363. 1988; Holttum, Fl. Males., Ser. II, Pterid. 2: 112. 1991; Boonkerd & Pollawatn, Pterid. Thailand: 206. 2000. – Type:  Lörzing 5161, Indonesia, Sumatra, Deli, Sibolangit (BO).

Pleocnemia stenosemioides Alderw., Bull. Jard. Bot. Buitenzorg, Ser. 3, 2: 164. 1920.

Description

Rhizome short, suberect, scales lanceolate, up to 8 by 1 mm, stiff, entire, dark-brown. Fronds distinctly dimorphic. Sterile frond: stipe 10–30 cm long, densely scaly at base, pubescent throughout, deeply castaneous to purplish; lamina oblong-subdeltoid, bipinnatifid, 15–25 cm long and wide; rachis like the upper part of stipe, very densely pubescent, gemmiferous at base of the uppermost or second upper pinna; lateral pinnae about 5 below pinnatifid indistinct apical portion; basal pinnae the largest, oblong-lanceolate, caudate at apex, unequally cuneate at base, up to 12 by 4 cm, middle pinnae sessile or adnate, caudate-acuminate at apex, subtruncate to broadly cuneate at base, lobed to half way towards costa; segments oblong to oblong-lanceolate, oblique to falcate, rounded to moderately acute at apex, entire; papyraceous, deep green, glabrous; costa densely pubescent, veins pinnate, veinlets simple or rarely forked, basal veinlets forming costal areoles, other veinlets free. Fertile frond: stipe longer, 20–45 cm long; lamina bipinnatifid, pinnae and segments much contracted. Sori round or extending along veins; indusia fairly large, glabrous .

Distribution in Thailand

PENINSULAR: Nakhon Si Thammarat, Yala.

Wider Distribution

Sumatra, and W Malaysia.

Ecology

Along paths in dense evergreen forests at low altitudes; terrestrial in non-calcareous area.

Similar species

Heterogonium pinnatum (Copel.) Holttum

Proposed IUCN Conservation Assessment

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

Notes

The gemmiferous rachis is distinct in this species , though this feature is usually overlooked.

Voucher specimens - Thailand

Middleton et al. 5439, Phangnga, Sra Nang Manora Forest Park (E).

Habit

Habit

Habit

Habit

Habit

Habit

Rhizome

Rhizome

Stipes

Stipes

Habit

Habit

Sterile frond

Sterile frond

Basal pinna

Basal pinna

Venation in sterile frond

Venation in sterile frond

Bulbil on sterile frond

Bulbil on sterile frond

Fertile frond

Fertile frond

Upper surface of fertile frond

Upper surface of fertile frond

Young sori with indusia

Young sori with indusia

Sori

Sori

Sori

Sori

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