In the 14th century the chapter house and the choir screen were added. The chapter house, started in 1288, is in an early decorated style, octagonal, with no central pier. It is reached from the choir by a passage and vestibule, through an entrance portal. This portal has five orders, and is divided by a central shaft into two subsidiary arches with a circle with quatrefoil above. Inside the chapter house, the stalls fill the octagonal wall sections, each separated by a single shaft with a triangular canopy above. The windows are of three lights, above them two circles with trefoils and above that a single circle with quatrefoil. This straightforward description gives no indication of the glorious impression, noted by so many writers, of the elegant proportions of the space, and of the profusion (in vestibule and passage, not just in the chapter house) of exquisitely carved capitals and tympana, mostly representing leaves in a highly naturalistic and detailed representation. The capitals in particular are deeply undercut, adding to the feeling of realism. Individual plant species such as ivy, maple, oak, hop, hawthorn can often be identified. The botanist Albert Seward published a detailed description of the carvings and their identification in 1935 and Nikolaus Pevsner wrote the classic description entitled "The Leaves of Southwell", with photographs by Frederick Attenborough, in 1945.