Plants forming dense clumps. Rhizomes pachymorph, neck 1--3 cm long. Culms to 5 m, to 1.5 cm in diam., pendulous; internodes to 30 cm, terete, lightly white-powdery at first, becoming yellow, longitudinal ribs very prominent, wall 1.5--2.5 mm thick; nodes with weakly prominent supra-nodal ridge, sheath scar prominent; branches 5--10, slender. Culm sheaths deciduous, far longer than internodes, distally papery and sparsely brown-setulose, apex narrow and linear, longitudinal ribs greatly prominent and red-brown, margins initially densely ciliate; auricles absent; oral setae scarce, erect, white-grey, to 3 mm; ligule ca. 1 mm, truncate or convex, glabrous; blade linear, revolute, glabrous, readily deciduous, margins usually serrulate. Leaves 3--5 per ultimate branch; sheath glabrous or apically slightly pilose; auricles absent or small; oral setae several, erect or spreading, yellow-brown, ca. 2--3 mm; ligule short, convex, to 1 mm; external ligule white-grey pubescent; blade narrowly lanceolate, to 7 × 0.7 cm, base cuneate, mid to dark green above, abaxially proximally grey-pilose, secondary veins 2--3-paired, margins spinescent-serrulate, transverse veins clear. Synflorescence unknown. Name from the Latin angustus, ‘narrow’.
Elegant, pendulous, very dense, slender culms and small, narrow foliage leaves. In its small leaves and prominent red-brown culm sheath veins it is similar to Fargesia nitida, but taller and more pendulous. The cultivated introduction has culms that become yellow, purple branchlets, purple to white leaf sheaths and dark green leaves. This species is sometimes considered a synonym of Fargesia ferax, but would appear to be a somewhat smaller bamboo with slightly different characteristics.
Borinda angustissima was introduced into the US from Wolong, Sichuan by J. Waddick in 1989.