1) a primary root that grows vertically downward and gives off small lateral roots. 2) one that has a deep central position in a line of growth or development.
pltintern
Christine Song supports both Project Learning Tree (PLT) US and Canada's program delivery and reporting, program research, and communications. Christine holds a Master of Environmental Science from the University of Toronto and and a combined degree with a Bachelor of Science in ecology and zoology and a Bachelor of Science in anthropology from the University of Calgary.
