Plants forming dense to rather open clumps. Rhizomes pachymorph, neck 2--5 cm long. Culms to 2 m, to 1 cm in diam., pendulous; internodes to 15 cm, terete, densely blue-grey waxy for first year, becoming yellow-green, redder after cold, longitudinal striations visible, glabrous, cavity small, wall very thick; nodes prominent, supra-nodal ridge obscure, sheath scar prominent; branches initially (5)-7-(9), strong, red-tinged. Culm sheaths very persistent, much shorter than internodes, very tough, initially light green, distally and marginally purple-tinged, becoming ruby red, glabrous, apex broad and sloping, longitudinal ribs obscure, becoming red-coloured, margins membranous and glabrous; auricles large and triangular, membranous; oral setae absent; ligule to 3 mm, obliquely truncate, serrate, finely ciliate, glabrous; blade narrowly triangular, glabrous, reflexed and strongly angled to higher side of sheath apex, persistent. Leaves 3--5 per ultimate branch, mostly deciduous in winter; sheath glabrous, margins glabrous, often pink-purple; auricles absent; oral setae absent; ligule convex, to 2 mm, tomentose; external ligule shortly white-ciliate; blade lanceolate or broadly lanceolate, to 5 × 0.7 cm, fresh mid-green, base cuneate, glabrous, secondary veins 2-3-paired, margins spinescent-serrulate, transverse veins distinct. Synflorescence unknown. Name frigidorum affinis, Latin, related to frigidorum ‘of cold places’.
Small thick-walled pendulous culms with nearly all foliage leaves deciduous in hard winters, new leaf blades growing terminally from old sheaths in spring. Leaf sheaths and blades indistinguishable from those of B. frigidorum, though generally smaller, but culm sheaths markedly different, with larger, naked auricles and membranous, glabrous margins. Among the most hardy of all Borinda species introduced so far. Culm internodes feel smooth, but longitudinal lines are visible.
As with B. frigidorum, the lack of vegetative parts in the type collections for several species names published previously makes it very difficult to relate this species to those names without further fieldwork in China.
Borinda frigidorum aff. was first introduced into the UK from Zhi Ben Shan in Yunnan Province of China in 1995 (Stapleton 1048).