The scapes (stems or culms) of a Thamnochortus fraternus plant grow in a dense tuft (or caespitose) as so many restios. The culms of T. fraternus are simple and smooth, occasionally reaching heights of about 1 m, commonly only a little over half that. The culms have narrowly lanceolate, erect bracts, brown and cartilaginous with pointed tips on the stem nodes. Plant diameter is about 20 cm at the base, 80 cm at the top.
The species distribution is in the Western Cape from the Cape Peninsula to around Bredasdorp. The habitat is coastal flats and well-drained slopes in limestone soils at elevations ranging between 50 m and 200 m.
The plant is considered near threatened in its habitat by human activities and invasive alien plant species early in the twenty first century (Dorrat-Haaksma and Linder, 2012; Leistner, (Ed.), 2000; Privett and Lutzeyer, 2010; www.plantzafrica.com; www.redlist.sanbi.org).