Culm leaves are deciduous with dense pubescence. Lesions can be seen on the leaf collar, culm, culm nodes, and panicle neck node. The north east of Cornwall lies on Carboniferous rocks known as the Culm Measures. The firebox was very wide to allow combustion of anthracite waste, known as "culm". Culm walls are thin, branching only at the top. In the next year, the pulpy wall of each culm slowly hardens. The under roofing is of bamboo culm. Nodal infection causes the culm to break at the infected node (rotten neck). During the third year, the culm hardens further. The easiest and most practised cultivation method is culm or branch cutting. Where the blade meets the culm there is a structure called the ligule. Internodal infection of the culm occurs in a banded pattern. To the north of Dartmoor are the Culm Measures and Exmoor. Each new culm that shoots up is larger than the last. A second branch, the Culm Valley Light Railway, opened on 29 May 1876.