Abstract text: Bundling of cellulose microfibrils and interaction with hemicelluloses is important in cell mechanical properties and expansion. These processes rely on surface properties of the fibrils, yet there are many aspects that are poorly understood such as the extent of cellulose crystallinity and the fibril shape and number of chains. Using 2D solid-state NMR of 13C labelled never-dried plants and isolated fibrils, six major glucose environments are resolved which are common to the cellulose of softwood, hardwood and grasses. We show there are only two glucose environments that reside within the microfibril interior, and these correspond to crystalline cellulose I-beta. The other four environments reside on the surface. The ratio of these glucose residues is 1:2, which is consistent with a cellulose 18-chain microfibril having 6 core and 12 surface chains, although other microfibril sizes are possible. There is no amorphous cellulose in fibrils isolated from wood. These advances change substantially both the interpretation of solid-state NMR studies of cellulose and the understanding of cellulose microfibril structure and crystallinity. They provide a basis for future studies of fibril diversity across plants, and will allow studies of the various fibril surfaces and interactions.