Sentence:  A coppice may be large, in which case trees, usually ash ("Fraxinus") or maple ("Acer") are cut, leaving a massive <WSD>stool</WSD> from which up to 10 trunks arise; or small, in which case trees, usually hazel ("Corylus"), hawthorn ("Crataegus"), or willow ("Salix"), are cut to leave small, underground <WSD>stools</WSD> producing many short stems. ... One consequence of coppicing is that the <WSD>stool</WSD> enlarges because each subsequent growth of shoots occurs on its outside. The diameter of a <WSD>stool</WSD> is thus directly related to its age. ... <WSD>stool</WSD> 1. A tree stump that is capable of producing new shoots. 2. The permanent base of a coppiced tree. 
Meaning of the word marked with <WSD> tags:  A plant that has been cut down until its main stem is close to the ground, resembling a stool, to promote new growth.