Robust, upright dioeciou s perennial, 1–4(–5) m high, forming dense rafts on acid peat. Rhizome 10–15 mm diam., horizontal, branched, covered with tightly appressed, overlapping scales; scales 10–15 × 15–20(–30) mm, ovate to broadly ovate, chartaceous, cream, pale brown to sometimes brown, lustrous, nerves slightly distinct to indistinct, apex rounded and mucronate. Roots 3 – 5 mm diam., 25–30 cm long, white, drying to grey, soft, spongy, with few (if any) rootlets. Culms up to 5 m tall, 10–15 mm diam., gradually tapering toward distal end, brittle, rigid, upright, terete to subterete, smooth to sometimes slightly grooved, green and usually glaucous when young, becoming red-brown to yellow-brown with age; branched in upper 2/3; branches numerous, slender, firm, flexible, upright, terete to subterete, often slightly compressed on one side; basal 140–200 mm of culm conspicuously swollen with soft, spongy, light brown tissue; pith absent, with 3 hollow triangular segments, these deteriorating to a ± circular cavity. Culm base with 3–7 loosely appressed, overlapping scales; scales 10–50 × 15–20(–40) mm, ovate to broadly ovate, coriaceous, light brown to brown, nerves distinct, apex rounded and mucronate. Leaves along culm solitary, distant, tightly appressed, gradually tapering toward tip; lamina 15–50 × 15–50 mm, ovate to broadly ovate, chartaceous, brown to dark brown, fading to grey, appressed to and sheathing culm, nerves indistinct; basal leaves with pectinate fringe, upper leaf margins entire or fractured into rectangular segments; apex rounded, with mucro 0.6-1.0 mm long. Inflorescence a terminal panicle, often with cymose branching near base, up to 150 mm long, red-brown, upright to spreading, sometimes drooping; male inflorescence dense, crowded; female inflorescence sparse, diffuse; flowers subtended by 2 bractlets, the 2 bractlets subtended by 1 bract; inflorescence branchlets subtended by reduced leaves. Bracts 5–7 × 3–4 mm, elliptic, lanceolate to ovate, light brown to red-brown, chartaceous, apex with mucro 1–2 mm long, margins usually membranous and fimbriate. Bractlets 1 .5–2.0 × 0 .8–1 .0 mm, elliptic to lanceolate, membranous, light brown to light red-brown, apex acute to acuminate, margins usually entire. Flowers pedicellate to almost sessile. Tepals 6, in 2 whorls of 3, 2.0–3.0 × 0.4–0.5 mm, subulate to lanceolate, light brown to yellow-brown, channelled, apex acute to weakly acuminate, mucronate. Stipe 0.6–0.8 mm long. Male flowers with 3 stamens; filaments 1.8–2.0 mm long, anthers 1.0–1.3 × 0.2–0.4 mm, cream, unilocular, medifixed, pollen yellow; pistil rudimentary. Female flowers with 1 pistil; style 0.8–1.3 mm long, pink, papillose on adaxial surface, decurrent with ovary on abaxial surface; ovary 0.3–0.7 × 0.2–0.6 mm, ± globose, amber to dark brown, vertical groove on adaxial surface; staminodes 3, each 0.5–0.8 mm long. Fruit 1.2–1.5 × 0.5–0.7 mm, narrowly ellipsoid, sides dark brown, suture light brown to cream-brown, surmounted by persistent, long style; dehiscing along abaxial suture. Seed 0.7–0.8 × 0.5–0.6 mm, shortly oblong to broadly ovate, light orange-brown when fresh, soon fading to light brown, sometimes with white blotches; testa membranous, surface bireticulate, primary pattern prominent with square t o polygonal ridges c. 1 mm wide, secondary pattern obscure to weak, irregular, ridges 5–7 mm wide; endosperm white. Chromosome number 2n = 1 8 (Murray & de Lange 1999, AK 235948; B. G. Briggs pers. comm., NSW 90806) .

A Sporadantho traversii differt rhizomatibus majoribus, culmis robustis erectis (non flexuosis), basem versus conspicue tumidis, marginibus pectinatis foliorum basalium, inflorescentiis ferrugineis, partibus floralibus semineque parveioribus, et fructu dehiscenti .

Slender, upright to sprawling dioecious perennial, 0.6-1 .8(-2 .5) m tall, forming dense somewhat flaccid rafts on peat an d peaty soils. Rhizome 3-10 mm diam., horizontal, sparingly branched, covered with tightly appressed, overlapping scales; scales 3-12 × 2-12 mm, broadly ovate to ± deltoid, chartaceous, dark brown, lustrous, nerves indistinct, apex rounded and mucronate. Roots 3-4 mm diam., 5-12 cm long, grey, drying to tan, soft, spongy, with few (if any) rootlets. Culms up to 2 m long, 1-5 mm diam., gradually tapering toward distal end, firm, flexuose, slender, terete, smooth, dark green-brown to brown, often blotched black; branched in upper 2/3, branches numerous, firm, flexuose, scrambling, terete; basal 50-65 mm of culm slightly swollen with soft, spongy, light brown tissue; pith absent, with 3 hollow triangular segments, these deteriorating to a ± circular cavity. Culm base with 3-7 loosely appressed, overlappin g scales; scales 8-25 × 10-12 mm, ovate to narrowly ovate, coriaceous, light brown to brown, nerves distinct, apex rounded and mucronate. Leaves along culm solitary, distant, gradually smaller toward distal end; lamina 15-30 × 6-11 mm, narrowly ovate, chartaceous, tan, brown to grey-brown, appressed to and sheathing culm, nerves distinct; margins entire to praemorse, sometimes cream; apex rounded, with mucro up to 8 mm long. Inflorescence a terminal panicle, often with cymose branching near base, 30- 150(-200) mm long, dark dull brown, upright to spreading; male and female inflorescences sparse, not crowded; flowers subtended by 2 bractlets, 2 bractlets subtended by 1 bract; inflorescenc e branchlets subtended by reduced leaves. Bracts 5.5- 10.0 × 2.6-3.0 mm, ovate, narrowly ovate to lanceolate, light brown, membranous, apex acuminate, margins fimbriate. Bractlets 5.2-5.8 × 1.0-1.6 mm, lanceolate, membranous, light brown to yellow brown, apex acuminate, margins entire. Flowers pedicellate to almost sessile. Tepals 6, in 2 whorls of 3, 4.0-6.0 × 1.0-1.2 mm, lanceolate, light brown, channelled, keeled, apex strongly acuminate. Stipe 0.3-0.4 mm long. Male flowers with 3 stamens; filaments 1.6-3.0 mm long, anthers 1.8-2.3 mm long, cream, unilocular, medifixed, pollen yellow; pistil rudimentary. Female flowers with 1 pistil; style 1.0- 1.5 mm long, pale orange, papillose on adaxial surface; ovary 0.6-0.7 × 0.3-0.4 mm, ellipsoid, brown to light brown, glossy; staminodes 3, each 1.5- 1.6 mm long. Fruit 3.0-3.5 × 1.0-1.2 mm, oblongellipsoid, light brown to brown, sutures not prominent, surmounted by persistent short style; indehiscent. Seed 1.2–1.5 × 0.9–1.0 mm, oblong to broadly ovate, dark brown; testa membranous; surface bireticulate, primary pattern prominent with rectangular to rectangular-polygonal, ridges c. 1 mm wide, secondary pattern prominent, irregular, ridges 5–7 mm wide, endosperm white. Chromosome number 2n = 18 (Murray & de Lange 1999 (fig. 1J); AK 235305).