Slender Yoke-moss

Zygodon gracilis is a dioicous, acrocarpus moss that grows in turfs of around 5 cm tall. The squarrose, lanceolate leaves bends away from the stem when moist and becomes contorted when dry. The leaves have distinctive toothed margins near the apex that sets it apart from other Zygodon species. Newer leaves appear dull green that become reddish-brown lower down in the shoot. Sporophytes are very rare and have only been documented twice, both in England in 1866 and most recently in 2002. The species do not exhibit any specialized asexual reproductive structures in the wild.

The species has only been found to grow on dry limestone, either pure limestone outcrops or stone walls made out of carboniferous limestone. Moreover, the rock surface must face north or northwest such that it can intercept mist and rainwater.