Close-up of the fossilised bark of a Lepidodendron sp. giant fern showing leaf scars. Lepidodendron is an extinct genus of primitive, vascular, tree-like plants, also known as scale trees, related to the quillworts and lycopsids (club mosses). They were part of the coal forest flora. They sometimes reached heights of 50 metres (m), and the trunks were often over 1 m in diameter. This specimen is from the Upper Carboniferous, or Pennsylvanian, subperiod (around 323-299 million years ago) and was collected in UK.