Location: Public Horticulture and Engagement Unit
2023 Annual Report
Objectives
Objective 1: Collect, propagate, preserve, evaluate, document, display, distribute, and introduce woody and herbaceous landscape ornamentals with enhanced aesthetic appeal, resistance to extreme weather, resistance to pests and diseases, and enhanced ecosystem benefits. Collection activities will focus on native plants due to difficulties with collecting plants in most other countries. [NP301, C1, PS1A]
Objective 2: Disseminate scientific and practical information to floral and nursery crop industries, to public gardens, to the increasing number of visitors to the U.S. National Arboretum and its Website, and to the general public interested in gardening. [NP301, C2, PS2B]
Sub-objective 2.a. Develop exhibits and interpretive signage that reflect current relevant ARS horticultural research programs, including the scientific mission of the U.S. National Arboretum.
Sub-objective 2.b. Develop educational programming to increase awareness of ARS research and germplasm preservation taking place at the U.S. National Arboretum.
Approach
The U.S. National Arboretum will continue to serve the public need for scientific research, education, and gardens that conserve and showcase plants to enhance the environment. This will be accomplished by maintaining outstanding gardens, plant collections, and public displays in an environmentally responsible and aesthetically pleasing manner. New ornamental cultivars and germplasm will be acquired using the Collections Policy and the newly developed Strategic Plan as a guide, and in support of the National Plant Germplasm System. Plants will come from nursery sources, wild-collected, or the USNA research program. Plants with superior landscape attributes will be propagated for distribution and evaluation. Staff will continue to utilize integrated pest management (IPM) in management of their collections and will explore the use or demonstration of other technologies such as solar power, green roofs, rain gardens, and water wise gardens as funds allow.
Plant records will be updated and coordinated with GRIN-global, and information will be uploaded to the publicly accessible Arboretum Botanical Explorer database. A new exhibit and educational program, GrassRoots, will be put in place. Educational opportunities will be optimized and implemented to provide formal and informal educational programming through exhibits, signs, publications, web pages, lectures, workshops, and tours. Volunteer and internship programs will continue to be supported.
Progress Report
Progress was made on all objectives, which fall under National Program 301. Under Objective 1 - The Gardens Unit enriches the living plant display collections and benefits global scientific research by incorporating documented germplasm into the gardens at the National Arboretum. The Unit is responsible for curating and maintaining thirteen gardens and collections on 451 acres. A systematic review of the plant collections and inventories to determine the value and scientific merit of the plants within our living collections was undertaken this year. Where accessions were not deemed worthy of continued cultivation, they were removed. We have made progress in writing the Collection Development Plans for eleven of our most vital collections, including Conifers, Native Plants, and our Asian and Azalea Collections. This effort included a more strategic focus and a direct link to and collaboration with the Arboretum's Floral and Nursery Plants Research Unit's Germplasm Project to tie the plant genetic resources of the Gardens Unit's Collections with the National Plant Germplasm System (NPGS). The Gardens Unit has begun the integration of our internal plant records database (BGBASE) with NPGS's Germplasm Resources Information Network (GRIN) Global Database, principally through the collaboration of the Gardens Unit Botanist and the Floral and Nursery Plants Research Unit's germplasm project lead scientist.
More than 12,600 Arboretum records have been added to GRIN-Global this year. More than 220 trees were planted in collections, and nearly all are growing well. We have added a total of 491 new accessions to the living collections this fiscal year. A total of 26,458 living plants comprise the managed collections and are represented by 14,960 accessions. In addition, there have been 6,015 accession records and 19,368 plant (inventory) records edited and updated this year.
Plants in the Springhouse Run Stream Restoration site are maturing, and the focus continues to center on the removal of invasive plant species. The well-documented Oak decline in the Mid-Atlantic region is unfortunately prevalent at the National Arboretum, with mature trees of Quercus montana being driven to near extinction from the grounds. In an effort to understand the impact of this decline, a thorough survey of the nine species recorded to be native to the Arboretum has been ongoing. From this effort, three species, Quercus marylindica (Black jack), Q. palustrus (Pin oak), and Q. veluntina (Black oak), have been shown to be represented by a critically reduced number of trees.
From our cultivated Inventory, we continue to evaluate the horticultural merit of Rosemary (Salvia rosemarinus), American dogwood (Cornus florida), and Siberian Cypress (Microbiota decussata). American nursery industry collaborators are currently evaluating this germplasm. The American dogwood selection is resistant to several fungi (i.e., Discula anthracnose and powdery mildew) and has the potential as a breeding stock that may revitalize commercial production of dogwood. The rosemary has enhanced winter hardiness and may extend the range of cultivation of the species.
Surveillance and removal of invasive plants throughout the Arboretum continue to focus on preserving gardens, collections, meadows, and woodlands at the U.S. National Arboretum. This effort is being done by a combined team approach using the expertise of Arboretum's horticulture team and the outside contractor Invasive Plant Control, Inc.
Under Objective 2 – A few examples of direct interaction of Gardens Unit staff with key stakeholders include, staff-led arboricultural tours of USNA Gardens and Collections, a tour to a Washington Area Blind Athletes Association group focusing on a visual description of the Arboretum and engaging smell and hearing senses to connect with the group; Washington Area Master Gardener Programs; a short course on plant identification; the 36th Annual Lahr Native Plant Symposium; a "Day of Arboriculture Symposium" for the Mid-Atlantic Chapter of the International Society of Arboriculture; and, giving a grounds tour to the Agriculture Innovation Mission for Climate Summit meeting contingent. Fee-based programs reached over 300 people, generating more than $19,756 (gross). Of particular note was a sold-out, fully bilingual Spanish/English half-day, hands-on workshop for landscape crew members. USNA staff taught basic identification of woody plants, an introduction to IPM, pruning best practices, and best practices regarding tree planting, watering, and mulching.
Eight National Bonsai & Penjing Museum special exhibits or events were held in the Bonsai Museum during FY23, including 3 stakeholder-related exhibits. These included a lecture on the horticulture of bonsai and a bonsai repotting demonstration to Road Scholar (which reached 200 virtual attendees); developed and presented a curriculum for "Bonsai Basics: Chrysanthemum Bonsai Course" [which is five classes conducted over the summer and fall of 2023]; and gave health and aesthetic design advice and public bonsai critiques to Brookside and Northern VA bonsai club. A book about the recent gift of Chinese stones was published. This book, Cultivated Stones: Chinese Scholars' Rocks from the Kemin Hu Collection at the U.S. National Arboretum, provides an educational context to the major gift of Chinese scholars' rocks we received from Kemin Hu in 2020. The natural forms of rocks in China, collected for display in gardens and home interiors as art objects, convey a connection long nurtured in China between the creative forces of nature and those of humankind.
After several years of COVID-related hiatus in the recruitment of interns and volunteers, a full slate of interns and several new volunteers were onboarded.
Currently under development is a suite of interpretive signage and web/app content about the role of Civilian Conservation Corps Camp NA-1-DC in developing the grounds of the U.S. National Arboretum from 1931—1941. We are conducting primary source research at the National Archives and elsewhere to share this hugely significant but little-known and under-valued facet of Arboretum history. Camp NA-1-DC was the first African American CCC camp in the Washington, DC, area. Enrollees cleared and graded land, built bridges and roads, installed fencing, and planted the Arboretum's first nurseries, creating the backbone of the grounds as they still exist today.
Accomplishments
1. Integration of Arboretum internal plant records database into the national global database. The Gardens Unit has begun the incorporation and amalgamation of our internal plant records database (BGBASE) with the National Plant Germplasm System (NPGS) Germplasm Resources Information Network (GRIN) Global Database. This effort included a more strategic focus and a direct link to and collaboration with the Arboretum's Floral and Nursery Plants Research Unit's Germplasm Project to tie the plant genetic resources of the Gardens Unit's Collections with the NPGS. This effort was made principally through the collaboration of the Gardens Unit botanist and the Floral and Nursery Plants Research Unit's germplasm project lead scientist. We successfully added more than 12,600 Arboretum records to GRIN-Global this year.
2. Connecting Cultures: Japanese Flowering Cherries in America, symposium. Since the mid-19th century, the appreciation of Japanese flowering cherries has been growing in the United States, melding Japanese aesthetics and techniques with a distinctly American flair. Today, the U.S. National Arboretum stands as a center of American appreciation for Japanese flowering cherry trees, growing about 60 cultivars. The oldest flowering cherry trees on the Arboretum's grounds were planted in the early 1950s, and these aging trees provide an opportunity for us to experiment with a traditional Japanese method of tree rejuvenation. Noted Japanese expert Kurato Fujimoto worked with our Arboretum Gardens Unit staff for the week preceding this symposium to teach and install traditional-style wooden crutches to support the heavy branches of two old weeping cherry trees. The symposium program featured four speakers who covered the history of Japanese cherry trees in America, ancient cherry trees and restorative practices in Japan, the flowering cherry research program at the Arboretum, and a tree-side presentation of the traditional Japanese support system.
