北江铁线蕨 bei jiang tie xian jue

Plants usually 20-30 cm tall. Rhizomes erect, short, scales castaneous-brown, linear. Fronds clustered, horizontally spreading; stipe castaneous-black, glossy, 5-10 cm, ca. 1 mm in diam., glabrous; lamina 1-pinnate, linear-lanceolate in outline, 13-18 × 3-4 cm, ca. 2 cm spaced; costae and stalks same color as stipe; pinnules opposite or subopposite, 6-8 pairs; stalk 2-3 mm, articulate at apex, persistent after pinnules fall; blade obovate-triangular, ca. 1.5 × 1.5 cm, papery, brownish, abaxially glaucous and glabrous, adaxially glossy, base rounded or rounded-cuneate, margin entire, upper margin truncate; distal pinnules similar but smaller; veins multidichotomously branching, reaching cartilaginous margins, visible on both surfaces. Sori 1(or 2) per pinnule; false indusia brown, rectangular, up to 1 cm, leathery, upper margins flat and straight, entire, persistent.

● Guangdong (Beijiang).

The outline of Adiantum chienii is similar to A. gravesii; the plant differs by being much taller and larger, and the indusia narrowly linear, horizontally attached at upper margin.