Dendrology :

... from the Ancient Greek word meaning "tree" and Greek word meaning "study", is the science of trees, and more generally the study of woody plants.

Woody plants may be trees, shrubs, etc and lianas. There is no sharp boundary between plant taxonomy and dendrology. However, woody plants do not only belong to many different plant families, but these families may be made up of both woody and non-woody members. Some families include only a few woody species. This severely limits the usefulness of a strictly dendrological approach. Dendrology tends to focus on economically useful woody plants, their identification and horticultural or silvicultural properties.

http://en.wikipedia.org/wiki/Dendrology

http://www.woodcollectors.org/index.htm

http://www.cnr.vt.edu/dendro/dendrology/main.htm

http://www.public.iastate.edu/~bot356/index.htm

http://www.ces.ncsu.edu/depts/hort/consumer/factsheets/trees-new/index.html

http://www.woodworking.org/WC/woodsampler.html

http://www.cnr.vt.edu/dendro/dendrology/main.htm

http://www.floridata.com/index.cfm

http://hgic.clemson.edu/index.htm

http://www.kidsarus.org/go4it/Opportunities/Competitions/arborday.htm

http://www.woodzone.com/properties.htm

http://www2.fpl.fs.fed.us/WoodID/woodid.html

http://www.arborday.org/treeguide/index.cfm

http://www.gypsymoth.ento.vt.edu/vagm/Treeimages/treeguide.html

http://www.museum.state.il.us/muslink/forest/htmls/trees.html

http://www.for.gov.bc.ca/hfd/library/documents/treebook/treebook.pdf