Carex pilulifera, the pill sedge, is a European species of sedge found in acid heaths, woods and grassland from Macaronesia to Scandinavia. It grows up to 30cm (10inches) tall, with 2–4 female spikes and 1 male spike in an inflorescence. These stalks bend as the seeds ripen, and the seeds are collected and dispersed by ants of the species Myrmica ruginodis.
Varieties:
The culms of Carex pilulifera grow to a length of 8cm-30cmcm (03inches-10inchescm), and are often noticeably curved.[2] The leaves are 5- long and 1.5mm2mm wide, and are fairly flat.[2] The rhizomes of C. pilulifera are very short, giving the plant a caespitose (densely tufted) appearance.[2] The tussock grows outwards through the production of annual side-shoots.
The inflorescence comprises a single, terminal, male (staminate) spike, and 2–4 lateral female (pistillate) spikes.[2] The spikes are clustered together, and the whole inflorescence is 1- long.[2] The female spikes are 4mm8mm long, ovoid or approaching spherical,[2] and contains 5–15 flowers. The female spikes are attached directly to the stem, and each is subtended by a bract which does not form a sheath.[2] The male spike is 8- long and much narrower.[2]
Carex pilulifera has a wide distribution in Europe, extending from Macaronesia and the Balkan Peninsula to Scandinavia.[3] It grows on acidic substrates including heathland, grassland and woodland. It typically inhabits soils with a pH of 4.5–6.0.[2]
As the seeds of C. pilulifera ripen, the culms bend, and can eventually touch the ground.[4] The seeds are then dispersed by ants, particularly Myrmica ruginodis,[4] in a process known as myrmecochory, and are eaten by other insects, such as the ground beetle Harpalus fuliginosus.[4]
Carex pilulifera was described by Carl Linnaeus in his 1753 work Species Plantarum, which marks the starting point of botanical nomenclature.[3] The specific epithet Latin: pilulifera means "bearing small globular structures", in reference to the female spikes.[5]