while the upper female spikes are erect. The utricles (seeds) of C. binervis are long and broadly elliptical, with a rough, notched beak long. They are purplish brown or sometimes partly green, and both the plant's scientific and common names refer to the fact that the utricles are marked with two conspicuous green veins. C. binervis has a chromosome number of 2n = 74. Distribution and ecology Carex binervis has an oceanic distribution, occurring only in areas of high rainfall, from Finland and Norway, through the British Isles, Germany, Belgium and France, to Spain and Portugal. Within the British Isles, Carex binervis has a westerly and northerly distribution, and is more abundant in Scotland, Wales and Ireland than in England. Plants from Morocco that were previously referred to C. binervis are now treated as a separate species, C. paulo-vargasii. Carex binervis grows in acidic, siliceous environments, including "damp heaths, moors, rocky places and mountainsides"; together with species such as Deschampsia flexuosa, it is a "useful indicator of acid substrate". The species has been recorded at altitudes of up to on Glyder Fach in north Wales, and there are reports of occurrences up to in the Scottish Highlands. Although sedges are chiefly wind pollinated, insect pollinators have been observed to visit C. binervis occasionally. Taxonomy In 1800, James Edward Smith published an article in the Transactions of the Linnean Society of London, titled "Descriptions of five new British species of Carex", which included the first descriptions of Carex davalliana, C. binervis, C. tomentosa (a synonym of C. filiformis), C. micheliana (a synonym of C. flacca) and C. laevigata. After the Latin diagnosis of Carex binervis, Smith writes: This species appears to have been confounded with C. distans; and from Lightfoot's description of the green angles of the fruit, I presume it to have been what he intended under that name. It is considerably larger than the real distans, the spikes black intermixed with green rather than yellowish, and the female ones often branched or compounded at their base. Its most essential and decisive character however consists in the two strong deep-green nerves or ribs which run along each side of the fruit externally near the edge. The arillus is also broader and more compressed than in C. distans. Carex binervis is classified in Carex subsection Elatae, part of Carex section Spirostachyae, alongside C. laevigata and other species. Natural hybrids are known