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American Society of Consulting Arborists

  • 7000 North Resort Drive Tucson, AZ, 85750 United States (map)

December 4th, 11:30 AM to 12:30 PM

The Systematics of Trees–How All the World's Trees Are Related and What It Means

Matt Ritter, Ph.D., Cal Poly

We share the world with millions of other species and engage with many of them on a daily basis. Those of us who study, grow, and work with trees depend on them for our livelihood, enjoyment, and intellectual fulfillment. Whether you use, exploit, conserve, or just admire trees, having a context in which to understand their relatedness is important. Learning the genealogy of common trees, although practically important, can also be an aesthetic and spiritual pursuit. The more we know about trees and their relationships, the more wondrous nature becomes, and the more deeply we can engage with these incredible organisms. There are well over a quarter million named plant species, 60,000 of which grow as trees. What species of trees are out there in the world and how are they classified? How can we make sense of all this diversity? Dr. Ritter will give an overview of the relationships among the world's trees and our current understanding of their phylogeny and modern taxonomy.

December 5th, 8:30 AM to 9:30 AM

Tree Growth and Development–How Wood, Branches, and Leaves Are Formed

Matt Ritter, Ph.D., Cal Poly

An understanding of how wood, branches, and leaves form is crucial for effectively identifying and working with trees. Flowering trees and conifers form wood and support branches in different ways. Leaves are not borne on all trees in the same way. Genetically determined characteristics in trees can help us identify, plant, prune, and maintain them properly, and tell us what to expect as they mature. Wood is not only one of the world's most valuable commercial products, it is also infinitely variable and incredibly beautiful. How does it form in different types of trees? How do the trunk, bark, and branches relate to leaves, photosynthesis, and growth? Join Dr. Ritter as he investigates the formation and structure of leaves and branches as well as trunks and the wood inside them. He will explain how wood is formed, how trunks increase in thickness, and the cells and tissues that are important for the functioning of a tree.