Carex riparia was first described by William Curtis in his 1783 work Flora Londinensis.
It is easily confused with Carex acutiformis, the lesser pond sedge, but can be told apart by its greater number of male spikes, which grow close together at the top of the culm.

The leaves of C. riparia are up to 160 centimetres (63 in) long by 6–20 millimetres (0.24–0.79 in) wide, glaucous, and narrowing at the tip to a trigonous point.
The stems are 60–130 cm (24–51 in) tall, rough, and sharply triangular in section, making C. riparia Britain's largest species of Carex.
They bear 1–5 female spikes, each nearly cylindrical and generally overlapping with the next, and 3–6 more densely arranged male spikes.
Each female spike is 3–10 cm (1.2–3.9 in) long, often with some male flowers at the tip, while male spikes are 2–6 cm (0.8–2.4 in) long.
The fruits of C. riparia are utricles, 5–8 mm (0.2–0.3 in) long, with an inflated ovoid shape.
They taper to a distinct, bifid beak, which bears three stigmas.

Carex riparia is known to hybridise with a number of other sedge species, including Carex acutiformis (forming Carex × sooi), C. lasiocarpa (forming C. × evoluta), C. rostrata (forming C. × beckmanniana), C. vesicaria (forming C. × csomadensis), C. elata and C. flacca.
Carex riparia was first described by William Curtis in his 1783 work Flora Londinensis. It is easily confused with Carex acutiformis, the lesser pond sedge, but can be told apart by its greater number of male spikes, which grow close together at the top of the culm.
The leaves of C. riparia are up to 160 centimetres (63 in) long by 6–20 millimetres (0.24–0.79 in) wide, glaucous, and narrowing at the tip to a trigonous point. The stems are 60–130 cm (24–51 in) tall, rough, and sharply triangular in section, making C. riparia Britain's largest species of Carex. They bear 1–5 female spikes, each nearly cylindrical and generally overlapping with the next, and 3–6 more densely arranged male spikes. Each female spike is 3–10 cm (1.2–3.9 in) long, often with some male flowers at the tip, while male spikes are 2–6 cm (0.8–2.4 in) long. The fruits of C. riparia are utricles, 5–8 mm (0.2–0.3 in) long, with an inflated ovoid shape. They taper to a distinct, bifid beak, which bears three stigmas.
Carex riparia is known to hybridise with a number of other sedge species, including Carex acutiformis (forming Carex × sooi), C. lasiocarpa (forming C. × evoluta), C. rostrata (forming C. × beckmanniana), C. vesicaria (forming C. × csomadensis), C. elata and C. flacca.
Carex riparia