Trees Ii

'frees contribute a major part of fuel, fodder and fruit, and are an im of bioenergy. They are now needed in large numbers more portant source than ever before for afforestation and social forestry, so that fast-grow ing and multipurpose trees assume great importance. After extensive in discriminate deforestation and rapid depletion of genetic stocks, efforts are now being made to evolve methods for clonal mass propagation of improved and elite trees. Production of short-duration trees with a rapid turnover of biomass, and induction of genetic variability through in vitro manipulation for the production of novel fruit and forest trees, which are high-yielding and resistant to pests and diseases, and trees which display increased photosynthetic efficiency are in demand. These objectives are well within the realm of horticultural and forest biotech nology. Some of the recent advances, such as the regeneration of com plete trees from isolated protoplasts, somatic hybridization, and the Agrobacterium-mediated transformation in various tree species have opened new vistas for the genetic engineering of fruit and forest trees. This book is a continuation of the earlier volume Trees I, and presents 31 chapters on fruit, forest, nut and ornamental trees, such as avocado, pineapple, crabapple, quince, pistachio, walnut, hazelnut, date palm, oil palm, cacao, rubber, maple, sweet-gum, poplars, birches, Chinese tallow, willows, oaks, paper mulberry, rhododendrons, Scots pine, Calabrian pine, Douglas-fir, redwood, ginkgo, cycads and some flowering trees.

This paper addresses questions of quasi-isometric rigidity and classification for fundamental groups of finite graphs of groups, under the assumption that the Bass-Serre tree of the graph of groups has finite depth. The main example of a finite depth graph of groups is one whose vertex and edge groups are coarse Poincare duality groups. The main theorem says that, under certain hypotheses, if $\mathcal{G}$ is a finite graph of coarse Poincare duality groups, then any finitely generated group quasi-isometric to the fundamental group of $\mathcal{G}$ is also the fundamental group of a finite graph of coarse Poincare duality groups, and any quasi-isometry between two such groups must coarsely preserve the vertex and edge spaces of their Bass-Serre trees of spaces. Besides some simple normalization hypotheses, the main hypothesis is the ``crossing graph condition'', which is imposed on each vertex group $\mathcal{G}_v$ which is an $n$-dimensional coarse Poincare duality group for which every incident edge group has positive codimension: the crossing graph of $\mathcal{G}_v$ is a graph $\epsilon_v$ that describes the pattern in which the codimension 1 edge groups incident to $\mathcal{G}_v$ are crossed by other edge groups incident to $\mathcal{G}_v$, and the crossing graph condition requires that $\epsilon_v$ be connected or empty.

This well-illustrated seven-volume work (1906-13) covers the varieties, distribution, history and cultivation of tree species in the British Isles.