The Magazine of the Arnold Arboretum VOLUME 72 • NUMBER 2 The Magazine of the Arnold Arboretum VOLUME 72 • NUMBER 2 • 2014 CONTENTS Arnoldia (ISSN 0004–2633; USPS 866–100) 2 Hamamelidaceae, Part 1: Exploring the is published quarterly by the Arnold Arboretum Witch-hazels of the Arnold Arboretum of Harvard University. Periodicals postage paid Andrew Gapinski at Boston, Massachusetts. Subscriptions are $20.00 per calendar year 18 Did American Chestnut Really Dominate domestic, $25.00 foreign, payable in advance. the Eastern Forest? Remittances may be made in U.S. dollars, by check drawn on a U.S. bank; by international Edward K. Faison and David R. Foster money order; or by Visa, Mastercard, or American Express. Send orders, remittances, requests to 33 Reading Tree Roots for Clues: The Habits purchase back issues, change-of-address notices, of Truffles and Other Ectomycorrhizal and all other subscription-related communica- Cup Fungi tions to Circulation Manager, Arnoldia, Arnold Rosanne Healy Arboretum, 125 Arborway, Boston, MA 02130- 3500. Telephone 617.524.1718; fax 617.524.1418; e-mail [email protected] 40 The Castor Aralia, Kalopanax septemlobus Arnold Arboretum members receive a subscrip- Kyle Port tion to Arnoldia as a membership benefit. To become a member or receive more information, Front cover: Flowers of a hybrid witch-hazel cultivar, please call Wendy Krauss at 617.384.5766 or Hamamelis × intermedia ‘Jelena’ (accession 462-65-A). email [email protected] Photo by Kyle Port. Postmaster: Send address changes to Inside front cover: Illustration of American chestnut Arnoldia Circulation Manager (Castanea dentata) from François André Michaux’s The Arnold Arboretum The North American Sylva, Volume 3, published in 125 Arborway 1819. Note that the illustration uses the old synonym Boston, MA 02130–3500 C. vesca and an alternate spelling of the common name, “chesnut.” Nancy Rose, Editor Andy Winther, Designer Inside back cover: The leaves of Kalopanax septemlobus Editorial Committee accession 841-81-A, which grows near the Arboretum’s Phyllis Andersen Rehder Pond, developing bright greenish yellow fall color. Peter Del Tredici Photo by Kyle Port. Michael S. Dosmann William (Ned) Friedman Back cover: Fall-flowering common witch-hazel Kanchi N. Gandhi (Hamamelis virginiana) blooms in a Minnesota garden. Photo by Nancy Rose. Copyright © 2014. The President and Fellows of Harvard College Hamamelidaceae, Part 1: Exploring the Witch-hazels of the Arnold Arboretum Andrew Gapinski amamelidaceae, the witch-hazel family, Arnold Arboretum has a rich history with the includes approximately 30 genera repre- family, from plant exploration to the naming Hsenting around 100 species of deciduous and introduction of its members to cultivation. trees and shrubs. Members of the family are The Arboretum’s Hamamelidaceae collection, found in both temperate and tropical regions which currently comprises ten temperate region of North and Central America, Eastern Asia, genera, can be found in groupings throughout Africa, the Pacific Islands, and Australia. The the Arboretum landscape. Specific locations KYLE PORT Many witch-hazels display attractive fall color; seen here, Hamamelis × intermedia ‘Arnold Promise’ (accession 380- 94-C) with red orange foliage and Hamamelis virginiana f. rubescens (accession 527-92) with yellow foliage. Hamamelidaceae, Part 1 • 3 All In the Family Corylopsis Loropetalum Fortunearia Parrotia The Arnold Arboretum currently has Fothergilla Parrotiopsis living specimens representing these Hamamelis Sinowilsonia genera within Hamamelidaceae: Liquidambar × Sycoparrotia KYLE PORT (ALL) KYLE PORT Chinese winter-hazel (Corylopsis sinensis); American sweetgum (Liquidambar styraciflua); Large fothergilla (Fothergilla major) include the area around the Hunnewell Visitor As the ground begins to warm in April, sev- Center, the Leventritt Shrub and Vine Garden, eral species of Corylopsis—commonly called scattered among the trees in the North Woods, the winter-hazels—produce many pendulous on the edges of the hickory (Carya) collection, clusters of bell-shaped yellow flowers. The near the summit of Bussey Hill, and among the fothergillas (Fothergilla) round out the family’s jewels of the Explorers Garden. flowering season in the Arboretum with their As autumn arrives at the Arboretum, the flow- bottle-brush-like white blooms in May. Beyond ering season for the witch-hazel family begins, the showy flowering of these genera, many are and will carry through until spring. Starting also aesthetically valuable for their unique in October, common witch-hazel (Hamamelis foliage, vibrant fall colors, and, in the case of virginiana)—a New England native—begins to Parrotia, attractive exfoliating bark. Given bloom, the straplike yellow petals of its fragrant these attributes, perhaps no other plant group- flowers extending on warm days and curling ing holds greater ornamental potential and yet up when temperatures drop near freezing. This is so underutilized in today’s landscape than show can persist into December even as the the witch-hazel family. This two-part article snow begins to fall. Other members of the witch- explores various historical, taxonomic, and hor- hazel genus represent the earliest of bloomers, ticultural facets of Hamamelidaceae taxa in the starting in January and lasting well into March— Arboretum’s collection. We begin with Hama- a remarkable sight in the depths of winter. melis, the genus for which the family is named. 4 Arnoldia 72/2 • October 2014 Hamamelis Whilst winter’s hand is yet heavy on the land the Witch-hazels boldly put KYLE PORT forth their star-shaped yellow blossoms but the native Hamamelis vernalis is over-shadowed by its more brilliant Chinese and Japanese relatives. Ernest H. Wilson, Plant Hunting, 1927 Witch-hazel (Hamamelis) is the most well-known Hamamelidaceae genus among gardeners and includes the only native New England representative of the family—Hamamelis virginiana, the common witch-hazel. There are two other North American species, H. vernalis (vernal or Ozark witch-hazel) and H. ovalis (big-leaf witch-hazel), and two Asian relatives, H. mollis (Chinese witch-hazel) and H. japon- Witch-hazel flower petals can furl and unfurl depending on air temperature. ica (Japanese witch-hazel). All of these Seen here are flowers of Hamamelis mollis ‘Princeton Gold’. ANDREW GAPINSKI A common witch-hazel (Hamamelis virginiana) in fall bloom, growing in Virginia’s Shenandoah National Park. Hamamelidaceae, Part 1 • 5 species are shrubs or small trees inhabiting temperate regions. They share charac- teristically narrow, straplike MICHAEL DOSMANN flower petals and capsulate fruit that is explosively dehiscent, capable of eject- ing seeds as far as 10 meters (33 feet). Much work has been done to create hybrids (H. × intermedia) between the Chinese and Japanese species, resulting in the development of horticul- turally desirable selections. Today these hybrids, as well as cultivars of H. mollis, are the witch-hazel family members most popular with Yellow flowers and yellow fall foliage blend on the branches of this common American gardeners. Both witch-hazel. the North American and Asian witch-hazels have a rich history, with specimen in question, blooms start as early as fascinating stories of discovery and much hor- October and can last into December. The spe- ticultural potential. cies’ fragrant flowers are composed of four yel- low, straplike petals that furl and unfurl with North American Discoveries the temperature swings of late autumn. In Common witch-hazel has a wide-ranging native many cases, full bloom occurs when the plant’s distribution along the east coast from Nova yellow fall foliage is still present, making it dif- Scotia to Florida and west to the Mississippi ficult to appreciate the flowers’ full grandeur. River, petering out in the Ozarks. Its western This is viewed by some as an aesthetic fault of limit runs from eastern Texas to Minnesota. It the plant, but to those who know what to look is commonly found in forest understories as a for, it is quite a remarkable display. With noth- large multi-stemmed shrub. For non-gardeners, ing else in bloom, the common witch-hazel has witch-hazel may be a familiar name not as a little competition for pollinators seeking a late forest-dweller but for its use as a component in season food source. first-aid and skincare products. Native Ameri- The Arboretum’s largest concentration of H. cans used witch-hazel for its healing properties, viriginiana can be found in the North Woods, and open-minded New Englanders soon recog- just past the Aesculus collection along Meadow nized its potential. In 1866, the first commercial Road, uphill from the short stretch of post-and- witch-hazel extract distillery was founded in rail fence. A visit to explore this nook should be Essex, Connecticut, by Thomas Newton Dick- part of any autumn walk in the Arboretum. A inson. Today, the distilling facility is located in bit farther down Meadow Road, at the northern East Hampton, Connecticut, and is the world’s end of Rehder Pond, is the Arboretum’s oldest largest source of witch-hazel extract, still pro- accession (14693-D) of common witch-hazel, duced from witch-hazel wild-harvested from wild-collected as a plant from western Massa- New England’s woodlands. chusetts and brought back to the Arboretum in The flowering time of common witch-hazel 1883 by Jackson Thornton Dawson, the Arbo- is definitely unique. Just as it seems that the retum’s first plant propagator. last of the years’ blooms have faded, H. vir- Steps away from this specimen grows another giniana comes into flower. Depending on the one of the Arboretum’s centenarian witch- 6 Arnoldia 72/2 • October 2014 hazels, Hamamelis vernalis accession 6099-D. Unlike common witch-hazel, the vernal witch- hazel, as the name suggests, flowers very early in the year (January through March). Although MAYER ROBERT its geographic range overlaps with that of com- mon witch-hazel, it only grows natively in the Ozark highlands of Missouri, Arkansas, and Oklahoma, and in small populations in Texas and Louisiana.