Plants rhizomatous; rhizomes elongate, flaccid, thick, whitish, imbricate. Culms 30-130 cm, forming large clumps. Sheaths glabrous, rounded dorsally; ligules 2-3 mm; blades 10-46 cm long, 6-15 mm wide, persistent or deciduous, flat or involute, adaxial surfaces ridged, not scabrous, margins smooth or slightly scabrous, sharply pointed, blades of upper leaves strongly divergent. Panicles 12-40 cm, with 2-12, more or less equally spaced branches; branches 16-25 cm, erect or somewhat divergent, axes pubescent, extending up to 5 cm beyond the spikelets; disarticulation at the base of the glumes, spikelets falling intact at maturity. Spikelets 14-21 mm long, 2-3 mm wide, narrowly oblong, appressed, closely imbricate. Glumes straight, sides appressed pubescent, keels ciliate or hispid, acute; lower glumes 10-14 mm, 2/3-4/5 as long as the upper glumes, 1-veined; upper glumes exceeding the floret, 3-6-veined; lemmas shorter than the upper glumes, shortly appressed pubescent, 1-3-veined, acute; paleas a little longer than the lemmas; anthers 5-13 mm, well-filled, dehiscent at maturity. 2n = 122-124.

Spartina anglica is a naturally formed amphidiploid, derived from S. ×townsendii, that was first recognized as a separate species in 1968. It has been introduced (like S. ×townsendii) for reclamation of tidal mudflats. It differs from Spartina ×townsendii in its wider and more widely divergent upper blades, longer ligules, longer, more hairy spikelets, and longer, well-filled anthers.