The Arnold Arboretum of Harvard University
April 2011


In this issue
  • Arboretum Horticulturists Help Track Ash Pest
  • April Classes Explore Gardening and Climate Change
  • Plant Spotlight on Forsythia x intermedia 'Karl Sax'
  • New Cellphone Tour Highlights Explorers Garden
  • Members' Tour Day Features Weld Hill Building Tour
  • Engage Your Family in the Wonders of Nature
  • Free General and Theme Tours Begin in April
  • Celebrate Spring's Arrival at the Birds & Bards Festival

  • April Classes Explore Gardening and Climate Change
    Bill McKibben

    The extreme weather events of 2010 offer timely reminders of environmentalist Bill McKibben's characterization of our planet as increasingly and violently out of balance. McKibben argues that our best hope for survival depends on scaling back to concentrate on essentials, building more resilient societies and economies, and creating both actual and virtual communities that will help us respond to future challenges. Join us at Trinity Church in Copley Square to hear the urgent and pragmatic message detailed in his latest book, EAARTH: Making a Life on a Tough New Planet.

    The Arboretum offers a variety of programs in April to help you prepare for the growing season. Classes on growing plants from seeds, selecting native trees, and utilizing ground-covering plants are some of the practical classes taught by Arboretum staff and others that will help you and your garden grow.

    Plant Spotlight on Forsythia x intermedia 'Karl Sax'
    Karl Sax border forsythia

    The Arnold Arboretum has introduced many notable plants to cultivation through both plant exploration and hybridization. Among the latter is Forsythia x intermedia 'Karl Sax', a classic cultivar of border forsythia named for the Arboretum director who conducted extensive research on the genus. In April, the shrub bears a profusion of larger-than-typical, deep yellow to yellow-orange flowers along its arched stems, giving the entire plant a golden radiance. The growth habit is more dense and bushy than many border forsythias, and its enhanced hardiness helps budding flowers withstand extended Boston winters. F. x intermedia 'Karl Sax' may be seen on the State Lab slope near the ponds and in the Leventritt Garden, where it is planted alongside a selection of other notable Arnold Arboretum introductions.

    New Cellphone Tour Highlights Explorers Garden
    Cell phone tour logo

    For more than a century, the area now known as the Explorers Garden on Bussey Hill has proved the perfect spot to test plants of unknown or marginal hardiness. As a result, many of the new and exotic species collected by plant explorers were planted here, including landmark discoveries like the Franklin tree (Franklinia alatamaha), the paperbark maple (Acer griseum), and the dove tree (Davidia involucrata). Learn more about these and other amazing trees and shrubs planted in this Arboretum microclimate on our new cellphone tour, Adventures in the Explorers Garden. Starting in mid April, when you spot this logo posted in the Explorers Garden, dial 617.895.4085 and enter the tour stop number to hear about the plants and the explorers who brought them to the Arboretum.

    Members' Tour Day Features Weld Hill Building Tour
    Weld Hill Research Building

    Greet the season and reconnect with the Arboretum on Members' Tour Day. Members are invited to join us on Saturday, May 21, 2011 for a look inside the Arboretum's newly opened Weld Hill Research Building and for an exclusive walking tour of nearby landscapes including Peters Hill and the Conifer Collection. The event begins at Weld Hill with refreshments at 9:30am, followed by informal building tours. Landscape tours follow at 10:30am, led by Arboretum horticulture staff. Please reserve space by Friday, May 13 at 617.384.9400 or email

    Engage Your Family in the Wonders of Nature
    Kids Explore

    Share some time outdoors with your kids over spring break, and enjoy family adventures in the Arboretum landscape. On Friday, April 22 at 1:00pm, children aged 8 to 12 and accompanying adults are invited to search for signs of spring on a guided nature hike. On Saturday, April 30 at 11:00am, stop by the Hunnewell Visitor Center with kids aged 4 and up for a special family activity focused on cherry trees. Both offerings are free, though registration is required for the hike. In case of inclement weather, call 617.384.5209 for scheduling information.

    Free General and Theme Tours Begin in April

    Every spring visit to the Arboretum rewards the senses and refreshes the spirit. Make the most of your next exploration on a free guided tour led by a knowledgeable docent. General tours begin on April 9 and include introductions to seasonal plant highlights, insights into the Arboretum's research and collections, and much more. Special theme tours kick off on April 2 with a brisk stroll along the less-traveled paths of the Arboretum with Arboretum docent Rhoda Kubrick. On April 5 at 1:00pm, join Arboretum plant propagators for behind-the-scenes look at how plants are acquired and grown for the living collection from seeds, cuttings, grafts, and seedlings. Registration is required for the theme tours, so be sure to reserve space early.

    Celebrate Spring's Arrival at the Birds & Bards Festival
    Song Sparrow

    Participate in Boston's annual Birds & Bards Festival, April 28 through May 1, and explore birds, poetry, and nature in over 1,000 acres of greenspace along Boston's Emerald Necklace. The Birds & Bards Festival offers events at multiple sites, including guided walks, fun family activities, and evening events. Experiences at the Arboretum include a bird walk at 8:00am on Saturday, April 30; a nature poetry walk at 1:00pm on Saturday; and a landscape design tour on Sunday, May 1 at 1:00pm. All events are free, and no registration is required.

    All images from the Arnold Arboretum Archives except EAB photo by David Roberts of Michigan State University (courtesy of the U.S. Forest Service) and Bill McKibben photo courtesy of the author.

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    Arboretum Horticulturists Help Track Ash Pest
    EAB galleries

    In March, Arnold Arboretum horticulture staff assisted the U.S. Forest Service in efforts to survey populations of emerald ash borer (EAB) in the Hudson River Valley. An infestation of this exotic pest, which has killed millions of ash trees (Fraxinus spp.) across the midwest and Ontario, was discovered last July in Kingston, NY, on the Hudson's west bank. To determine how far EAB has advanced in the region, Arboretum horticultural technologists Jen Kettell, Sue Pfeiffer, and Kevin Block, along with intern Evan Meyer, helped volunteer crews search for EAB larvae in ash trees cut in survey zones on both sides of the river. Though the pest has not yet been detected on the river's east bank, the Forest Service will continue to monitor the area as part of an effort to slow the pest's advancement. Officials estimate that reducing the insect's spread by 10 percent could save 10 million dollars in pest management and tree removal costs.

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