Tree pine ("Pinus" species) the bark exudes sticky resin which deters attackers whereas in rubber trees ("Hevea brasiliensis") it is a milky latex that oozes out. The quinine bark tree ("Cinchona officinalis") contains bitter substances to make the bark unpalatable. Large tree-like plants with lignified trunks in the Pteridophyta, Arecales, Cycadophyta and Poales such as the tree ferns, palms, cycads and bamboos have different structures and outer coverings. Although the bark functions as a protective barrier, it is itself attacked by boring insects such as beetles. These lay their eggs in crevices and the larvae chew their way through the cellulose
Christmas tree production in the United States million Christmas trees valued at approximately $120 million. The majority of Christmas tree production occurs in the Willamette Valley region including Benton, Clackamas, Marion, Polk and Yamhill counties. In 2015, Washington State had approximately 250 Christmas tree farms with a combined 23,000 acres, yielding 2.3 million Christmas trees valued at approximately $35 million. The majority of Christmas tree production occurs in the western and southern portions of the Puget Sound region including Kitsap, Lewis, Mason and Thurston counties. Aside from Pennsylvania, several U.S. states in the Great Lakes region are key Christmas tree producers. The two most important production areas