59. Diplazium quadrangulatum (W. M. Chu) Z. R. He
四棱双盖蕨 si leng shuang gai jue
Basionym: Allantodia quadrangulata W. M. Chu, Acta Bot. Yunnan. 3: 333. 1981.
Plants evergreen, large. Rhizome erect, trunk up to 40 cm tall, up to 10 cm in diam., apex densely scaly; scales dark brown, linear-lanceolate, margin black, sparsely toothed; fronds caespitose. Fertile frond up to 2 m; stipe green, shorter than lamina, quadrangular (rachis also quadrangular, costae terete), up to 5 mm in diam., base slightly scaly; lamina 2-pinnate with pinnules pinnatilobate, ovate-oblong, up to 1.5 m, apex acuminate; lateral pinnae up to 13 pairs, alternate, slightly ascending, base truncate, apex acuminate; lower pinnae broadly lanceolate or oblong-lanceolate, up to 50 × 20 cm, with stalk up to 5 cm; pinnules up to 14 pairs, lanceolate or oblong-lanceolate, up to 10 × 3 cm, base truncate, pinnatilobate or incised, apex acuminate; lower pinnules shortly stalked; pinnule lobes up to 10 pairs, slightly ascending, slightly crenate, truncate at apex; veins pinnate, veinlets 7 pairs per lobe, ascending, simple, occasionally forked. Lamina papery when dry, green, glabrous on both surfaces; rachis and costae green, glabrous. Sori linear, 3(or 4) pairs per pinnule lobe, inframedial from costule to 1/2-3/4 of veinlet length, single or double on basal acroscopic veinlet; indusia brown, membranous, entire. Spores reniform, perispore with reticulate ornamentation.
● Evergreen broad-leaved forests; 1000-1300 m. S and SE Yunnan.
In some plants, the lamina is 1-pinnate, narrowly deltoid, ca. 35 × 25 cm; and the pinnae are lanceolate, pinnatipartite.
Diplazium quadrangulatum is distinct in the genus by having a quadrangular stipe and rachis.