A STUDY OF THE GENUS TAXUS DISSERTATION Presented In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy In the Graduate School of The Ohio State University By RAY ALBERT KEEN, B. S., M. S. The Ohio State University 1956 Approved by: Adviser Department of Horticulture and Forestry ACKNOWLEDGMENT The author wishes to acknowledge and express his grateful thanks to Professor L. C. Chadwick of the Division of Floriculture and Ornamental Horti­ culture for his patient guidance and cheerful en­ couragement in the pursuit of this study and for his foresight in establishing the Living Herbarium of Taxus in the Secrest Arboretum as a service to the nurserymen of Ohio and America. Space does not permit the naming of the many nurserymen, gardeners, directors of arboretums, and others who have freely shared plant materials and time. But special mention should be made of the Arnold Arboretum, Jamaica Plain, Massachusetts; of Mr. Walter Hunnewell and Mr. William H. Hatfield for permission to study the plants and records of the late Mr. T. D. Hatfield; and of the Ohio Nurserymen's Association for financial assistance. ii TABLE OP CONTENTS Page List of Illustrations ..................... iv Introduction ............... 1 Purpose of This Study ........................ 3 Review of Literature ........................... 3 Methods of S t u d y ............................... 11 Morphology..................................... 14 Chromosome Number in Taxus .................... 22 Discussion ..................................... 30 Descriptions of Species and Cions ............ 39 S u m m a r y ......................................... 193 Bibliography ............................... 195 lil List of Illustrations Figure Page 1 Planting Plan of the Living Herbarium of Taxus, Seorest Arboretum, Wooster, O h i o ....... ... 4 2 The Living Herbarium of Taxus of Secrest Arbor­ etum from the West ... *.......... 5 3 Winter 5uds of Taxus ........................... 16 4 Male and Female Flowers of Taxus at Anthesis ... 18 5 Seed of the Y e w ................ 20 6 Monoecious Twig of the Male Cion BROWN ANGLOJAP YEW ..................................... 21 7 Diploid Somatic Chromosomes of Taxu3 .......... 24 8 Taxus Chromosomes at Metaphase I in Meiosis .... 27 9 Removing Female Gametophyte from Taxus Seed .... 28 10 Haploid Somatic Chromosomes of Taxus ..... 29 11 Unpruned Four-year-old Yew from a Lateral Branch ...................................... 33 12 Taxus baceata L., White Marsh Plantation... ..... 40 13 Taxus baceata L., Longwood Gardens ............. 43 14 Cion BROOM ENGLISH YEW, Secrest Arboretum..... 45 15 Cion CHESHUNT-ENGLISH YEW, Secrest Arboretum-... 47 16 Cion COMPACT ENGLISH YEW, Secrest Arboretum .... 49 17 Cion D0VAST0N ENGLISH YEW, Newport, Rhode Island 51 18 Cion GLAUCOUS ENGLISH YEW, Secrest Arboretum ... 53 19 GOLDEN ENGLISH YEW, Tyler Arboretum, Lima, Pa. 55 20 Mixed Yew Seedlings, Fairview (Pa.) Nursery .... 57 21 Cion GRACEFUL ENGLISH YEW, Longwood Gardens .... 59 iv Figure Page 22 Branch Growth Habit of Cion GRACEFUL ENGLISH YEW .......................................... 60 23 Cion HEATH ENGLISH YEW, Secrest A r b o r e t u m 62 24 Cion IRISH ENGLISH YEW, Richmond, Va........... 64 25 Cion GOLDEN IRISH ENGLISH YEW, Tyler Arboretum 66 26 Cion MICHELL ENGLISH YEW, Secrest Arboretum ... 68 27 Cion OVEREYNDER ENGLISH YEW, Secrest Arboretum 70 28 Cion ROUNDTOP ENGLISH YEW, Secrest Arboretum .. 72 29 Cion SHORTLEAF ENGLISH, Young Plant ........... 74 30 Cion SHORTLEAF ENGLISH YEW, Old Plant ......... 76 31 Cion SPREADING ENGLISH YEW, Old Plant ......... 78 32 Cion SPREADING ENGLISH YEW, Young Plant ...... 79 33 Foliage Characteristics of Some Yew Species and Cions in the Tyler Arboretum, Lima, P a ...... 81 34 Cion WASHINGTON ENGLISH YEW, Tyler Arboretum .. 83 35 Cion YELLOW BROOM ENGLISH YEW, Tyler Arboretum 85 36 Cion YELLOW DOVASTON ENGLISH YEW, Masonic Homes, Elizabethtown, P a ..................... 86 37 English Yew, in Christ Church Cemetery, Green­ wich, Conn.................................... 89 38 Taxus canadensis Marsh, in the Arnold Arboretum 93 39 Taxus ohinensis Rehder, at the Hunnewell Estate 96 40 Taxus chinensis, Rehder, at the Morris Arbor­ etum ......................................... 97 41 Taxus cuspldata Sieb. & Zucc. at the Hall Estate, Bristol, R. I. ........ 100 42 "SIEBOLD" JAPANESE YEW and Cion GOLDTIP JAPANESE YEW, South Wilton (Conn.), Nursery 102 Figure Page 43 Nursery Block of Large "TAXUS CUSPIDATA CAPITATA" ....... 103 44 Cion ADAMS JAPANESE TEW, Secrest Arboretum .... 105 45 Cion BOBBINK JAPANESE TEW, Secrest Arboretum .. 107 46 Cion CUSHION JAPANESE TEW, Arnold Arboretum ... 109 47 DWARF JAPANESE TEW, Dense Type, Youngstown, Ohio ......................................... 112 48 DWARF JAPANESE TEW, Loose Type, Hunnewell Estate............... 113 49 DWARF JAPANESE TEW, Dense Type, Hunnewell Estate ....................................... 114 50 Cion BLUE JAPANESE TEW, Type Plant, Hiti N u r s e r y ............... ..................... ... 116 51 Cion GOLDTIP JAPANESE TEW, G. R. Hall Estate .. 119 52 Cion HITI JAPANESE TEW, Hiti Nursery, Pomfret, Conn. ................. 121 53 "TAXUS HITI" at the Arnold Arboretum ......... 122 54 Cion INTERMEDIATE JAPANESE TEW, Secrest Arboretum .............. 125 55 Cion PROSTRATE JAPANESE T E W ................... 127 56 Cion PYGMT JAPANESE TEW, Highland Park, Rochester, N. T. ......................... 129 57 THAYER JAPANESE TEW, Arnold Arboretum ........ 133 58 HUNNEWELL TEW, Arnold A r b o r e t u m ................ 139 59 HUNNEWELL TEW, Formal Hedge of Seedling Plants * at the Hunnewell Estate ..................... 140 60 ANGLO JAP TEW, Arnold A r b o r e t u m .............. 142 61 ANGLOJAP TEW Hedge on Hunnewell Estate 143 62 T. D. Hatfield’s List of Numbered Plants ...... 146 vi Figure Page 63 Cion ANDORRA ANGLOJAP YEW, Secrest Arboretum .. 151 64 Cion BLACK ANGLOJAP YEW, Arnold A r b o r e t u m 153 65 Cion BROWN ANGLOJAP YEW, Parent Plant ......... 155 66 Cion COLE ANGLOJAP YEW, Secrest Arboretum .... 158 67 Cion COSTICH ANGLOJAP YEW, Secrest Arboretum ♦. 160 68 Cion DUTWEILER ANGLOJAP YEW, Secrest Arboretum 161 69 Cion HATFIELD ANGLOJAP YEW, Young Plant ...... 165 70 Cion HATFIELD ANGLOJAP YEW, Old Plant ......... 166 71 Cion HENRY ANGLOJAP YEW, Type Plant, Henry Verkade Nursery, New London, Conn........... 168 72 Cion HICKS ANGLOJAP YEW, Type Plant ........... 171 73 Cion HILL ANGLOJAP YEW, Secrest A r b o ret um 173 74 Cion KELSEY ANGLOJAP YEW, Secrest Arboretum ... 175 75 Cion MOON ANGLOJAP YEW, Secrest Arboretum .... 177 76 Cion ROBUST ANGLOJAP YEW, Secrest Arboretum ... 179 77 Cion SEBIAN ANGLOJAP YEW, Secrest Arboretum ... 181 78 Cion STOVEKEN ANGLOJAP YEW, Secrest Arboretum . 183 79 Cion TOTEM ANGLOJAP YEW, Secrest Arboretum .... 185 80 Cion VERMEOLEN ANGLOJAP YEW, Secrest Arboretum 187 81 Cion WARD ANGLOJAP YEW, Secrest Arboretum .... 190 82 Cion WELLESLEY ANGLOJAP YEW, Secrest Arboretum 192 vii A STUDY OP THE GENUS TAXUS Introduction In American gardens the Yews have always been associ­ ated with quality* Their foreign origin, moderate growth rate and limited supply restricted their use to the estates of the wealthy* The few mature specimens in America today are to be found in the antebellum plantation gardens and cemeteries of the South, and on the grounds of the rapidly disappearing estates on Long Island and near Boston and other large cities on the Eastern Seaboard* With the passing of Quarantine 37, which prevented the importation of nursery stock, the nurserymen of America were forced to start propagating evergreens* Yews were con­ sidered difficult to propagate and slow to reach marketable size; consequently, the demands of the American gardener were met with quick growing and often inferior evergreens, such as Juniperus, Thu.1a and ChamaeCyprus. Undoubtedly the biggest factor in increasing the popu­ larity of the Yews has been the introduction of hardiness via the Japanese Yews, and the production of a wide variety of useful landscape forms in the cions and hybrids of this species* With the exception of some of the golden cions the English Yew is not reliably hardy north of Long Island and Philadelphia, The Japanese Yews are hardy in southern Canada* This increase in range has permitted the use of -2- this most valuable plant in the most populous region of the country. In order to meet the demand of the public for quality evergreens, the nurserymen have propagated Yews from almost any available source. Cuttings were taken from local estates and park plantings and plants in the nursery. Seed was collected from mixed plantings anywhere. The resulting plants were usually salable, though well described as “mongrels11 by one nurseryman. Others, less conscientious, would supply a name, or worse, market the plants to a gul­ lible public under some name which had current demand. The confusion of names resulting from such practices did not enhance the popularity of the Yews nor the nursery industry# The taxonomic difficulties of this genus remain today as a distinct handicap to the trade, and none will ad­ mit it more readily than the nurserymen. The varieties and cions of the English Yew have been produced over a period of centuries. Their introduction, evaluation and description have been slow and more or less orderly by reason of the time involved and the single species as a source. By contrast, the Japanese Yew was brought to America less than a century ago, and the first hybrids were planted since 1900. Since few records