FLORA OF ICELAND elements: Carex flava, Large Yellow-sedge, Trjónustör

Carex flava; The Large Yellow-sedge is an average-sized growing up to 45cm. It forms tufts without rootstocks.
  - The leaves are as long as the culm or shorter than the inflorescence. However, the inflorescence includes the long bracts, so the leaves can extend the spikes. The leaves are flat and often (especially after in the season) bended. The stomata are on the bottom side of the leaves. The bracts are much longer than the stem with the spikes. They have short (few mm) lighter colored sheath.
  - The inflorescence consists of a top male spike and a few (2-4) female spikes directly under the male spike. The scales below the female flowers/utricles are yellowish to brown with a green midrib and are pointed. The utricles are globose with a long beak. Their color varies from green to yellow.
  - It is a rare species recorded in the north of Iceland. I however, found it in the Mýrar district north-west of Borgarness. It grows along creeks and in bogs.
  - It is a member of the sedge family (Cyperaceae). The Icelandic name of this species is Trjónustör.

Two other related species are found on Iceland:
  (1): Carex demissa (Green Yellow-sedge): It is smaller and very often has an extra female spike far below the top spikes. It shares the long beaks on the utricles. Like C. flava, it is a rare.
  (2): Carex oederi aka Carex viridula (Small-fruited Yellow-sedge): This is a small sedge with darker green leaves. The utricles are usually shorter. It also misses the extra female spike of C. demissa. The shape of the female spikes are more globose than the ovoid female spikes in the other two species. This species is more common on Iceland.