Vol. 46 No. 2 Spring 1986 Page 2 The Great Catalpa Craze Peter Del Tredici 111 Prunus maackm, the Friends’s Plant Dividend for 1986 Gregory J. Waters Arnoldia (ISSN 0004-2633) is published quarterly m winter, spring, summer, and fall by the Arnold 13 Notes and Quotes on the History and Arboretum of Harvard University. Origins of the Amur Chokecherry (Prunus . Subscriptions are $12.00 per calendar year domestic, maackm) $15.00 per calendar year foreign, payable m advance. 25 Prunus maackm Single copies are $3.50. All remittances must be m Propagatmg U S dollars, by check drawn on a U S bank or by Alfred f. Fordham mternational money order. Send subscnptions, remittances, change-of-address notices, and all other 27 Japanese Honeysuckle: From "One of the subscription-related commumcations to Arnoldia, best" to Ruthless Pest The Arnold Arboretum, The Arborway, Jamaica Plain, Richard A. Hardt MA 02130. Postmaster: Send address changes to: 35 Botamcal Gold: Exploring the Treasures of Arnoldia the Harvard University Herbaria The Arnold Arboretum Carolme J. Swartz The Arborway Jamaica Plain, MA 02130 39 A + AAH + AMES + ECON + FH + GH + NEBC = "HUH": Systematic at Copyright © 1986, The President and Fellows of Botany Harvard Harvard College. Edmund A. Schofield, Editor 42 BOTANY: THE STATE OF THE ART Peter Del Tredici, Associate Editor Listening to Thirsty Plants Jan Brink, Design Consultant (Volunteer) John W Emset Marion D. Cahan, Editorial Assistant (Volunteer) Elise Sigal, Calendar Editor (Volunteer) 46 BOOKS Front cover Inflorescence and leaves of Catalpa spe- ciosa, the western, or hardy, catalpa. (See page 2.) Water- color pamring by Esther Hems. Courtesy of the artist. (See page 2). Opposite~ Inflorescence of the Japanese honeysuckle (Lomcera japonica L.). From Curtis’s Botamcal Magazine for 1834 (See page 27.) This page: A tiger swallowtail (Papiho glaucus (L // approachmg a hop tree (Ptelea tnfohata L.), one of the plants on which its larvae feed. From Mark Catesby’s Natural History of Carolina, Flonda, and the Bahama Islands (London, 1754). (See "Books," page 46.) Inside back cover: The elegant bark of the Amur chokecherry (Prunus maackii Rupr.). The conspicuous horizontal structures are len- ticels, pores through which gasses enter and leave the interior of the trunk Photograph by Albert W Bus- sewitz.Courtesy of the photographer (See page 11.) Out- side back cover An inflorescence of Prunus maackii. Photograph by Albert W. Bussewitz. Courtesy of the photographer. (See page 11.) The Great Catalpa Craze Peter Del Tredici Zealous promoters once made claims about the value of the hardy, or western, catalpa that far exceeded the tree’s true economic potential, obscuring its real worth Horticulturists, who make it their business In short, the catalpa has too many black to pass judgments on plants, generally con- marks against it to win favor with modern sider the catalpa tree a disaster. Although horticulturists. Yet, this was not always the very beautiful, its large, heart-shaped leaves case. There was a time, in the late 1800s, create a major litter problem when they fall. when planting catalpa was the thing to do, And during the growing season, their lovely, and people up and down the East Coast, soft-green tints are generally masked by across the Great Plains, and as far as Cali- infestations of powdery mildew. The catalpa fornia were madly planting the tree every- tree is among the last to leaf out in the where. The movement to plant catalpa was spring, and in the autumn its foliage turns a fad not dissimilar to the one of planting brown and shrivels in response to the first Paulownia in the middle Atlantic states touch of frost. today or Ailanthus in urban areas, from the The catalpa is sparsely branched; conse- early to mid-1800s. quently, for six months of the year it presents While the active planting of catalpa has by a very stark, almost gawky, appearance. Its and large ceased, the tree has managed to long pods, which provide the reason for the increase its range on its own, as spontaneous plant’s common name, the Indian bean tree, seedlings sprout up along highway embank- add a note of interest to the winter silhou- ments, roadsides, and stream banks ette, but in the spring, when they fall, they throughout the East Coast. In some towns, provide the home owner with yet another spontaneous catalpa is so well established reason to curse the tree. To top off this bleak that one is tempted to look upon it as part of situation, catalpa wood is quite brittle, and the native vegetation. small branches regularly break off during storms. The Two Species Without a doubt the flowers are the pri- There are two distinct species involved in mary ornamental feature of the catalpa. the parentage of these escaped catalpas. Both They are produced in early summer and rival are native to the eastern United States and, those of the common horse-chestnut (Aes- while very similar, occupy culus hippocastanum) in showiness, being nonoverlapping ranges in their wild state and have quite dis- quite large, pure white, and lightly speckled tinctive growth habits. The first, the southern with purple and yellow spots arranged in par- allel bands. Unfortunately, this bloom period catalpa, Catalpa bignonioides, occupied a rather limited range before the European set- lasts only about a week or so, depending on river banks from cen- the weather. tlement, growing along tral Alabama and Mississippi to western Florida. Because of its showy flowers, catalpa Opposite~ Leaf, shoot, fruits, seeds, and ovule of Catalpa was and speciosa From The Silva of North America, by Charles very quickly widely planted Sprague Sargent Drawmg by Charles E. Faxon. throughout the south, so that even the early 4 botanists could not determine its original time when botany, horticulture, and forestry range with certainty. were not seen as separate specialties; it con- The second species, the western, or hardy, tains, therefore, everything that was known catalpa, Catalpa speciosa, is geographically about trees through 1894. separated from its southern cousin, growing in a small area encompassing southern Apostles for Catalpa western Ken- Indiana, Illinois, Missouri, to E. E. and and northeastern According Sargent, two men, Barney tucky Tennessee, of and Robert of Wau- Arkansas. This disjunct population of catalpa Dayton, Ohio, Douglas kegan, Illinois, became apostles for the was not as distinct until 1853, recognized western the the former when Dr. John A. Warder of Cincinnati, catalpa during 1870s, and a book about the vir- Ohio, first described it. While it is difficult writing publishing tures of Catalpa speciosa, while the latter if not impossible to distinguish the two spe- was the principal contractor for the actual cies in the herbarium, they are fairly easy to planting of catalpa on large tracts of prairie separate in the field. For one thing, Catalpa owned by various railroad his speciosa blooms in late May or early June in companies. By own reckoning, Douglas had planted over New England, a good two weeks before two and a half million Catalpa bignonioides does. For another thing, seedlings throughout Kansas and Missouri in less than six years. Catalpa speciosa usually is a tall, narrow Barney’s pamphlet of 1878, Facts and Infor- tree, upwards of 80 feet in height, with a straight trunk, while Catalpa bignonioides is considerably smaller, usually around 40 feet, with a contorted or low-branched trunk and a wide spreading crown. In areas where the two species are planted together, there is often an overlap in the end of the Catalpa speciosa bloom and the start of the Catalpa bignonioides bloom. This raises the distinct possibility of hybridiza- tion, which, if it occurred, would give rise to trees intermediate between the parents in stature and in time of bloom. It is quite pos- sible that some of the spontaneous plants one sees along the roadsides are of hybrid origin, in contrast to the cultivated plants, which are usually identifiable as one species or the other. The question remains as to why and how these two species of catalpa came to be so widely planted that they became part of the spontaneous flora of the East. The answer eluded me for many years, until I consulted the fountainhead of information on trees, The Silva of North America, by Professor Charles This Sprague Sargent. many-volume Several fruits of Catalpa speciosa Photograph from the work is special because it was produced at a Archives of the Arnold Arboretum 1 5 mation in Relation to the Catalpa Tree, An Experimental Planting offers a clear of the of picture catalpa gospel A after the second edition of the day. year Barney’s pamphlet appeared, the most famous planting A railroad man, Barney saw the catalpa as of western was undertaken Hor- solving the specific problem of obtaining catalpa by atio Hollis Hunnewell, Charles Sar- railroad ties for the construction of new lines Sprague gent’s friend and relation. Hunnewell was across the treeless Great Plains. Barney felt first and foremost a businessman who served that catalpa wood was the ideal solution to either as director or of some this because it was president thirty- problem extremely four different railroads between 1852 and resistant to decay. Catalpa was further suited 1901. He was also deeply interested m plants. to the task since it grew incredibly fast and In 1880, at the age of sixty-five, he managed was not about what type of soil it particular to these two interests commis- required. Barney predicted that seedlings merge by sioning Robert Douglas to plant four hundred planted in good soil would produce four to acres of Catalpa speclosa and one hundred eight ties each after twenty-five to thirty acres of Ailanthus altissima on a tract of years of growth.