ARBORETUM INTERESTING IMAGE Do you know what this is? Click here to find out. To perform a custom search of the Arboretum site - type in a keyword or phrase. Or, go to our Site Map page to browse our page links. DIRECT ARBORETUM SUPPORT Donations -- Volunteering PRIVATE SUPPORT GROUPS Friends of the National Arboretum Herb Society of America National Capital Area Garden Clubs, Inc. National Bonsai Foundation

The Science of Color in Autumn Leaves Every autumn the US National Arboretum's sea of green foliage changes to a blaze of reds, yellows, oranges, purples, golds, and browns. Observing this annual phenomenon is simple; understanding it may be a little more complicated. You may have learned the basics of fall color change in grade school, but the science behind this annual autumn show is always fascinating. Why and how do certain trees become so colorful each fall? Weather and biology play key roles in the scientific explanation of a tree’s changing colors. Temperature may help dictate the color and its intensity, but it is only one of many environmental factors—such as soil moisture and the amount of sunlight—that influence the extent of the color display. Biology is perhaps the most important factor in foliage color changes. The plants’s process of creating and shedding leaves contributes to which colors are formed when, especially when photosynthesis ceases and its key element—green chlorophyll—disappears to uncover other hidden pigments. This is when autumn colors are revealed. For a more thorough description of the hows and whys of fall color, read the full article, The Science of Color in Autumn Leaves. To see examples of outstanding fall-color plants, visit our Fall Foliage Photo Gallery. We also have a list of plants that would look great in your yard, too.

EDUCATION New event: Full Moon Hikes for Groups December 1, January 29, and February 26 8:00 - 10:00 pm Book our popular Full Moon Hike for your group! Gather friends, family, co-workers, and others to enjoy this unique experience that is considered by many to be one of DC's best outings. The regular hikes sell out quickly and completely every month, so we are offering the new group hike as a way for you to enjoy and share this magical moonlit trip. Maximum 25 per group. Fee: $550. Registration required.   View Arboretum Calendar of Events

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RESEARCH USDA Grant Awarded for Development of a Microarray System for Universal Detection of Plant Viruses A USDA National Research Initiative grant was recently awarded to Dr. John Hammond and Dr. Ramon Jordan of the U.S. National Arboretum's Floral and Nursery Plants Research Unit, in collaboration with scientists at several other institutions. The grant is for $999,735 over a period of three years, with the goal of developing the capability to detect and identify plant viruses, from any type of plant, to at least the viral genus level. Most existing methods of virus detection are either virus-specific, or detect a number of related viruses within one group, and are unable to detect viruses of other taxonomic groups. In contrast, the microarray will consist of thousands of oligonucleotides (short DNA ‘probes’), each derived from nucleic acid sequences conserved between the genomes (RNA or DNA) of members of a particular taxonomic group, or between isolates of a particular viral species. These ‘probes’ are spotted in an array to a support surface. Total nucleic acids from plants are ...    Read Full Story   View Plant Introductions and Award Winners

Arboretum Information || Events & Education || Gardens & Horticulture || Research Activities Support the Arboretum || New Plant Introductions || USDA Plant Hardiness Zone Map || Comments Search Our Site United States National Arboretum 3501 New York Avenue, NE; Washington, D. C. 20002-1958 Tel: 202-245-2726    Fax: 202-245-4575 The U.S. National Arboretum is a division of the Beltsville Agricultural Research Center of the Agricultural Research Service of the U.S. Department of Agriculture Government System Usage Policy || USDA Nondiscrimination Statement || Privacy and Security Policy || Endorsement Disclaimer || Accessibility Disclaimer Last Updated November 17, 2009 12:12 AM URL= http://www.usna.usda.gov *###*