Lindsaea parallelogramma Alderw.
Lindsaea parallelogramma Alderw., Bull. Jard. Bot. Buitenzorg, Ser. 3, 5: 212. 1922; Holttum, Rev. Fl. Malaya ed. 1, 2: 335, f. 193. 1955 [‘1954’]; Kramer, Fl. Males., Ser. II, Pterid. 1: 220, f. 29. 1971; Kramer, Gard. Bull. Sing 26: 35. 1972; Tagawa & K.Iwats., Fl. Thailand 3: 139. 1985; Boonkerd & Pollawatn, Pterid. Thailand: 94. 2000.
Description from Kramer, Fl. Males., Ser. II, Pterid. 1: 220, f. 29. 1971.Rhizome short creeping, 1.5–2 mm diam.; scales fawn-coloured, narrowly triangular, to 2 mm long, up to c. 10-seriate at base, with a rather short uniseriate apex. Fronds close; stipe characteristically olivaceous-brown, dull, sharply quadrangular, adaxially channelled and pale-margined, c. 15–30 cm long, 1.5–2 times as long as the lamina. Laminae bipinnate, broadly oblong, sometimes wider than long (rarely simply pinnate and fertile, then linear), c. 10–20 cm long, with 1–4 pairs of lateral pinnae and a conform terminal one; primary rachis similar to the petiole, abaxially channelled. Pinnae patent or ascending, often contiguous, sessile, c. 8–18 cm long, 2–3.5 cm wide, the upper ones little or not shortened; secondary rachises similar to the primary, abaxially sulcate and pale-edged. Pinnules c. 15–30 to a side, mostly somewhat ascending, scarcely to slightly contiguous, herbaceous, mostly drying dark brownish green, not translucent, parallelogram-shaped, the larger 9–14 mm long, 3–5 mm wide, 2.5 to nearly 3 times as long as wide (except when the apex is caudiform), very little or not narrowed to the obliquely truncate apex. Upper and outer margin obliquely incised, the upper usually with 4, the outer with 1 incision, those of the upper margin reaching 0.25–0.33(–0.5), the apical ones often 0.5(–0.66); lobes parallel-sided, convex, entire or minutely erose, the basal broadest often with a shallow incision; sinus narrow, acute. Some pinnules occasionally caudate-protracted at the apex. Upper pinnules rather suddenly strongly reduced, several denticuliform ones confluent with the caudate, linear pinna-apex. Veins immersed or slightly raised, mostly evident, regularly anastomosing, forming a series of areoles 0.5 mm wide below the level of the incisions, rarely the larger lobes with another series. Sori one per lobe, up to c. 2 mm long, bi- to quadri-, mostly trinerval; indusium 0.2–0.25 mm, wide, entire, not reaching the margin by less than its width to about twice its width, reflexed at maturity. Spores very pale brown, trilete , smooth, c. 17–20 micrometres.
Distribution in Thailand
Peninsular Malaysia and Lingga Is.
Terrestrial in evergreen forests at about 400 m alt.
Proposed IUCN Conservation Assessment
Least Concern (LC). This species is widespread and not under any known threat.
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