VOL. XXXIV OCTOBER, 1933 No. 406 JOURNAL OF THE NEW YORK BOTANICAL GARDEN TREES AND SHRUBS OF THE ORIENT--III The Hardy Buddlejas HENRY TEUSCHER SHADE TREE CONFERENCE AT NEW YORK BOTANICAL GARDEN CAROL H. WOODWARD SURVEYING FOR THE DUTCH ELM-DISEASE CAROL H. WOODWARD ASIATIC IMMIGRANTS IN THE BOTANICAL GARDEN--IV JOHN K. SMALL POISON IVY ROBERT T. MORRIS, M.D. WILLARD G. BIXBY ROBERT T. MORRIS, M. D. "GARDENING WITH HERBS" T. H. EVERETT NOTES, NEWS, AND COMMENT PUBLISHED FOR THE GARDEN AT LIME AND GREEN STREETS, LANCASTER, PA. THE SCIENCE PRESS PRINTING COMPANY Entered at the post-office in Lancaster, Pa., as second-class matter. Annual subscription $1.00 Single copies 10 cents Free to members of the Garden THE NEW YORK BOTANICAL GARDEN BOARD OF MANAGERS HENRY W. DE FOREST, President CLARENCE LEWIS HENRY DE FOREST BALDWIN, Vice President ADOLPH LEWISOHN JOHN L. MERRILL, Vice President and Treas. HENRY LOCKHART, JR. E. D. MERRILL, Secretary KENNETH K. MACKENZIE ARTHUR M. ANDERSON H. DE LA MONTAGNE, JR., A. F. BLAKESLEE Asst. Treas. and Bus. Mgr. MARSTON T. BOGERT LEWIS RUTHERFURD MORRIS GEORGE S. BREWSTER H. HOBART PORTER N. L. BRITTON MRS. ARTHUR H. SCRIBNER THOMAS J. DOLEN EDMUND W. SINNOTT CHILDS FRICK SAM F. TRELEASE R. A. HARPER WILLIAM H. WEBSTER JOHN P. O'BRIEN, Mayor of the City of New York JOHN E. SHEEHY, President of the Department of Parks GEORGE J. RYAN, President of the Board of Education DIRECTOR EMERITUS N. L. BRITTON, PH. D., SC. D., LL. D. GARDEN STAFF E. D. MERRILL, SC. D Director-in-Chief MARSHALL A. HOWE, PH. D., SC. D Assistant Director H. A. GLEASON, PH. D Head Curator JOHN K. SMALL, PH. D., SC. D Chief Research Associate and Curator A. B. STOUT, PH. D Director of the Laboratories FRED J. SEAVER, PH. D., SC. D Curator BERNARD O. DODGE, PH. D Plant Pathologist FORMAN T. MCLEAN, M. F., PH. D Supervisor of Public Education JOHN HENDLEY BARNHART, A. M., M. D. .Bibliographer and Admin. Assistant PERCY WILSON Associate Curator ALBERT C. SMITH, PH. D Associate Curator SARAH H. HARLOW, A. M Librarian H. H. RUSBY, M. D Honorary Curator of the Economic Collections ELIZABETH G. BRITTON Honorary Curator of Mosses FLEDA GRIFFITH Artist and Photographer ROBERT S. WILLIAMS Research Associate in Bryology E. J. ALEXANDER .... Assistant Curator and Curator of the Local Herbarium HAROLD N. MOLDENKE, A. M Assistant Curator CLYDE CHANDLER, A. M Technical Assistant ROSALIE WEIKERT Technical Assistant CAROL H. WOODWARD, A. B Editorial Assistant KENNETH R. BOYNTON, B. S Head Gardener THOMAS H. EVERETT, N. D. HORT Horticulturist HENRY TEUSCHER, HORT. M Dendrologist G. L. WITTROCK, A. M Docent ROBERT HAGELSTEIN Honorary Curator of Myxomycetes E. B. SOUTHWICK, PH. D Custodian of Herbaceous Grounds ETHEL ANSON S. PECKHAM .. Honorary Curator, Iris and Narcissus Collections WALTER S. GROESBECK Clerk and Accountant ARTHUR J. CORBETT Superintendent of Buildings and Grounds JOURNAL OF The New York Botanical Garden VOL. XXXIV OCTOBER, 1933 No. 406 TREES AND SHRUBS OF THE ORIENT—III THE HARDY BUDDLEJAS1 Few people who are the proud possessors of a "butterflybush" in their garden and who delight in the great attraction which the sweetly fragrant flowers of this shrub have for butterflies realize that botanists now recognize more than 70 species of this genus. However, the great majority of these species inhabit tropical re­ gions of Asia, South America, and Africa, and since, consequently, they are not hardy with us out of doors, they shall not concern us in this article. About two thirds of all the known species of Bud- dleja—46 to be precise—are natives of Asia, and most of these again are to be found in the province of Yunnan, famous for the extraordinary wealth of its flora. But, tempting as this rich flora of Yunnan is to the explorer, it is exasperating to the western hor­ ticulturist who only too frequently finds it impossible to accom­ modate the beautiful Yunnan plants to our more rigorous climate. Only seven or eight of the species of Buddleja which so far have been introduced into cultivation—all of them native of Asia— can be grown successfully out of doors in the vicinty of New York, and of these only two are really first-class ornamental flow­ ering shrubs. There may yet be some good varieties among those which so far are only known from herbaria, such as B. myriantha Diels and B. heliophila W. W. Smith, from northwestern Yunnan and Tibet; B. nana W. W. Smith, from Szechuan and Yunnan; B. praecox 1 Named after the English botanist Buddie; also spelled Buddleia, Budd- lea, or Buddleya. Buddleja, however, is the original spelling in Linne's Species Plantarum. 209 Lingelsheim, and B. tibetica W. W. Smith, from Tibet. All of these, judging from herbarium specimens and from collectors' notes, appear to be rather promising. But, whether any of them will be able to compare favorably with a good form of B. Davidii, the most commonly cultivated butterflybush, will yet have to be seen. From a taxonomic standpoint the genus Buddleja presents con­ siderable difficulties, and to the horticulturist trying to find his way through the maze of forms, it appears as though many of the sup­ posed species would be better included as varieties in some other species. The distinction between closely related species is most frequently based on the length of the corolla tube, the position of the stamens in the tube, and the length of the calyx in comparison with the tube. The density and color of the tomentum on the leaves and inflorescence have also to be considered. None of these characteristics is very satisfactory or reliable. To increase the con­ fusion, most Buddlejas hybridize easily in cultivation, and to raise any of them from seeds from a locality where more than one spe­ cies is present is almost sure to result in a mixed hybrid offspring. Certain species which are supposed to be in cultivation, such as B. Fallowiana and B. stenostachya—even in herbarium specimens almost indistinguishable to me—I have never been able to obtain, though many times I have received seeds under these names from various European botanical gardens. The plants which I raised from these seeds were always hybrids, more or less intermediate between B. nivea and B. Davidii, their hybrid origin being betrayed by the great variability of the seedling plants. Under the name B. Forrestii I have never received anything but B. nivea; at least, I have never been able to see any appreciable difference. I am in­ clined to believe that either B. Forrestii is only a local variant of B. nivea which loses its distinguishing characteristics in cultivation, or that most of the plants which are in cultivation in Europe under the name B. Forrestii are nothing but B. nivea. Most hybrid Buddlejas which I have seen were inferior to the good forms of B. Davidii. The most promising seemed to me B. nivea xB. Davidii. The best form, of what I took for a second generation of this hybrid, I received under the name B. macro- stachya yunnanensis (a name which was later transferred as vari­ ety to the species B. nivea, where it will be mentioned). It com- bined the silvery-white tomentum of the leaves of B. nivea with the bright bluish-purple flowers and long spikes of B. Davidii. The location of the stamens in the tube and the size of the corolla varied in different plants; otherwise the seedling plants of this set looked fairly uniform. THE HARDIEST BUDDLEJAS The hardiest species of Buddleja which are in cultivation are the following: B. albiflora, B. alternifolia, B. Davidii, B. japonica, B. Lindleyana, and B. nivea; leaving out B. Fallowiana, B. For­ restii, and B. stenostachya, which as yet I do not understand. Buddleja japonica Hemsley and B. Lindleyana Fort, can be dis­ pensed with as being of so little ornamental value that they need not be considered for garden planting. Both may be readily dis­ tinguished from all others by their sharply 4-angled and more or FIGURE I. TWO closely related species of Buddleja—B. albiflora (above) with noticeably round twigs and pinkish-lilac (not white) flowers, and B. nivea (below), which is characterized by a silvery-white tomentum on its leaves and stems. less winged twigs. In It. japonica. the twigs are more strongly winged than in B. Lindleyana; the flower racemes of B. japonica are pendulous while those of B. Liudlevumi arc upright. The leaves of B. Lindleyana are ovate, shorter, and usually broader than those of B. japonica. which the accompanying photograph shows. Buddleja Lindleyana, a native of eastern China, is the pret­ tier of the two, but it has proved rather tender in the northern parts of this country. In the southeastern United States it is quite frequently found naturalized. B. japonica, as the name implies, is a native of Japan. Occasionally it is cultivated under the wrongly applied name B. curviflora, and I have also received it under the name B. ll'ilsouii, to which it has no right whatever. The hybrid between these two, B. intermedia Carriere, which first appeared in France as a chance seedling some 60 years ago, has never become widely known and is rare in cultivation. To judge from a colored engraving which Carriere gives in Revue Horticole (1873), the flowers in their shape and size suggest B. Lindleyana, while the foliage favors B. juponiea. It seems to be prettier than either of its supposed parents by virtue of its long pendulous racemes of rather showy violet flowers, hut as an orna­ mental shrub it will hardly be able to compete with B.