Carex riparia
Carex riparia, the greater pond sedge, is a species of sedge found across Europe and Asia. It grows in a variety of wet habitats, and can be a dominant species in some swamps. It is Britain's largest "Carex", growing up to tall, with glaucous leaves up to long. It hybridises with a number of other "Carex" species, including the closely related "Carex acutiformis" – the lesser pond sedge. A variegated cultivar is grown as an ornamental grass. Distribution and habitat. "Carex riparia" has a broad distribution over Europe and Western and Central Asia, with isolated occurrences in North  Africa. It can form large stands along slow-flowing rivers, canals, on the edges of lakes, and in wet woodland. It may be the dominant species in swamps, especially if there is standing water in spring, and is also found in tall-herb fens, alongside "Carex acutiformis", "Carex acuta" and other similar species. Description. "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 long by wide, glaucous, and narrowing at the tip to a trigonous point. The stems are 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 long, often with some male flowers at the tip, while male spikes are long. The fruits of "C. riparia" are utricles, 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". Horticulture. "Carex riparia", particularly the cultivar 'Variegata', is used as an ornamental grass in gardens with wet soils.