Kenneth D. Cochran,
Secrest Arboretum,
The Ohio State University,
Ohio Agricultural Research and Development Center,
and The Ohio State University Agricultural Technical Institute,
Wooster, Ohio.
A study was conducted to investigate the genetic origin of ornamental Taxus in the United States and further verify the nomenclature and origin of Taxus x media 'Hicksii.' Observations were made in the Chadwick Living Herbarium of Taxus in the Secrest Arboretum on the Wooster campus of The Ohio State University's Ohio Agricultural Research and Development Center and through visits to selected commercial nurseries in Ohio, Michigan, Pennsylvania, New York, and some New England states.
Interviews were held with people who selected various Taxus cultivars. Gardens and arboretums were visited to understand the origin of Taxus, and literature was reviewed. The study determined that nomenclatural errors do exist in reference to Taxus, but there are opportunities to implement corrections.
Classifying the genus Taxus has been discussed long and hard since Linnaeus wrote Species Plantarum in 1753. Subdividing the genus into one, six, seven, or eight species has been based on leaf characters, eventual size of plant, habit of growth, and geographical distribution of the genus throughout the world (Bailey, 1933). Naturally occurring varieties and selected cultivars have been named based on plant morphology and patterns of growth (Bailey, 1933; Chadwick and Keen, 1976). Sometimes plantspeople have designated cultivar names of Taxus solely on how they felt about a particular plant or how they found that plant to appear different in a nursery field from all others (Cochran, 1991-92).
In 1990, Dr. Edward M. Croom, botanist, University of Mississippi, and Ken Cochran, Secrest Arboretum, The Ohio State University, set out to identify leaf and branch characters for the 100-plus cultivars of Taxus in the Chadwick Living Herbarium of Taxus. With leaf and branch characteristics varying on a single cultivar according to the way the plant was oriented to the north, south, east, or west and according to the upper portion vs. the lower portion of a plant, it soon became apparent that the task was impossible. As Croom stated, "The best that we can do for starters is go to the wild and see what we can find in the different populations throughout the range for each species of Taxus."
Liberty Hyde Bailey stated in 1933 that it is impossible to designate a species that will include the exceptions of the horticultural varieties of Taxus (Bailey, 1933).
About 1843, H. H. Hunnewell began an Arboretum at Wellesley, Massachusetts, near Boston. Hunnewell took great interest in planting species of evergreens that had not previously been available in the United States. About 1866, Hunnewell received plants of the species Taxus cuspidata and Taxus cuspidata var. nana. These plants were received from the Parsons Nursery of Flushing, Long Island, New York. Parsons had obtained the plants from Dr. George R. Hall of Warren, Rhode Island. Hall brought these species to America from Japan through a plant collection trip in 1860. The author and Ethan Johnson of the Holden Arboretum, Kirtland, Ohio, along with Jack Cowles, their head gardener at Hunnewell, viewed the Hall plants growing on the Hunnewell Estate on September 21, 1991.
In 1886, Theophilus D. Hatfield began working for the Hunnewell family and eventually became the head hardener of the estate. Hatfield began a series of experiments about 1904 growing Taxus from seed, and his work was considered to be the largest ever undertaken for Taxus at that time in America (Klehm, 1929). He started by taking seed from Taxus baccata var. fastigiata, the Irish yew, which was growing near specimens of the Japanese yew, Taxus cuspidata, and the seedlings were raised. In a paper presented July 16, 1929, American Plant Propagators Association, Statler Hotel, Boston, Massachusetts, Hatfield reported that plants raised from his seedlings were a hybrid, concluding that the parent plants were growing near enough to cross with each other (Hatfield, 1929). There was no reporting of intentional crossing of Taxus by Hatfield. Hatfield died October 7, 1929, as a result of a fall from a ladder while picking seeds of Carolina hemlock; his left leg was badly broken; he sustained serious internal injuries; and tetanus was the immediate cause of death.
From Hatfield's writings we understand that he selected and numbered several varied forms of Taxus from his seedling experiments and eventually introduced them to the nursery trade as cultivars of a hybrid (Hatfield, 1921; Hatfield, 1929). Hatfield also reported that there were few marks of distinction in the various types of Taxus and that he was really led to believe that all yews are a form of Taxus baccata even though he used the designations Taxus baccata, Taxus cuspidata, and Taxus x media. His experiments also led him to believe that many well-defined forms would come true from seed. He was sure that his hybrid Taxus x hunnewelliana would come true from seed. He reported that most of the seedlings from seed of Taxus baccata var. fastigiata produced the upright type even though he named the offspring hybrids.
Hatfield indicated that the dwarf spreading variety, Taxus cuspidata var. nana got the lead in the nursery trade, but later the upright selection Taxus cuspidata var. capitata was brought into cultivation. Taxus cuspidata var. capitata was given a variety name, but the variety had the branching characteristics of the type of Taxus cuspidata which formed a central leader with distinct horizontal side branches.
In the Secrest Arboretum, all of the naturally seeded Taxus have taken on the central leader form of the type (species). The seed source for these seedlings has primarily been from more than 100 selections that have pollinated and fruited from among the various plants of Taxus cuspidata, Taxus baccata, and Taxus x media. There has been no indication of hybridization in the naturally seeded plants in the Secrest Arboretum. All seedlings have the appearance of a central leader plant.
In 1929, Hatfield reported to the American Plant Propagators Association that of the original English yews, Taxus baccata, only a few plants remained at Hunnewell. He further indicated that the Japanese varieties outperformed the English yew because of unusually severe winters that burned the south side of the plants and otherwise disfigured them. One particular selection, Taxus baccata 'Repandens,' was noted as a presentable performer, and it had an especially good chance to survive because in most winters it was below the snow line.
About the same time as Hatfield was growing seedlings at Wellesley, nurseryman Henry Hicks of Westbury, Long Island, New York, was growing seedlings at his Long Island nursery in the center of Nassa County, 25 miles from New York City. Henry was noted as an applied botanist, plant ecologist, and nurseryman of the Hicks Nurseries, Inc., one of America's oldest and finest nurseries (Wing, 1943). The nursery was started in 1853 by Henry's grandfather, Issac. Henry enrolled at Cornell University in 1888, the same year Liberty Hyde Bailey went there to teach and from there he saw a direction of where to go in his career. Henry was a crusader of yews for American gardens, and popularizing the Japanese yew was one of the achievements of the Hicks Nursery. Originally, Henry had an interest in hemlock, but he gave up that interest for yews. Henry cared about preserving the environment long before people knew what that concept meant (Cochran, 1991).
Henry thought that yews were fine plants as he had seen many beautiful specimens at the Dane Arboretum, Glen Cove, Long Island. In a 1924 Hicks catalog, Henry reported a new variety, Taxus x media 'Hicksii' from a 1902 collection at the Dane Arboretum. From among 1,000 seedlings of an old yew plant at the Arboretum, the Hicks yew was selected - "an interrogative point form, fruiting, dark green and handsome." Hicks called this a hybrid, but there was no intentional crossing indicated. From Hicks' seedling population, another upright form was selected. Eventually Chadwick gave the second plant the name Taxus x media 'Costich' as it was a male selection. Hicks Nursery did not use the name 'Costich;' they just designated them as male or female Hicks yew (Cochran, 1991).
It is apparent that the origin and production of Taxus in the United States originated from the collections of Hall, seedling work of T. D. Hatfield, the Parsons Nursery, and nurserymen like Henry Hicks. It also seems likely that the Japanese types were hardy in New England, but the Japanese types along with the English types were hardy in Long Island. If there is only one species of Taxus as some have proposed, Taxus baccata, then at least it seems that provenance does indeed make a difference with regard to hardiness. It would seem convenient to the nursery trade to keep the two species designations Taxus baccata and Taxus cuspidata, with hardiness being a deciding factor between the two, the latter being the hardier type.
With Taxus cultivars, pressed specimens are of little value. Croom and Cochran would not have been able to observe the varied leaf and branch characteristics on a single cultivar without constant recourse to the living plants in the Secrest Arboretum. Pressed specimens cannot show the plant forms that are so critical to the ornamental character of the cultivars; therefore, a living collection is essential for identification.
Taxonomists have suggested the name Taxus x media to be the hybrid designation for most of the cultivars that have been introduced since the work of Hatfield and Hicks. The author's research has not shown any intentional hybridization of Taxus; therefore, the genetic basis for Taxus x media needs to be verified by more genetic analysis.
Ever since modern Taxus cultivars were first named, nurserymen and plantspeople have made cultivar selections from seedling populations and from designated differences within a nursery field of known Taxus. In seed propagation, segregation of the genes is to be expected, and variability is the outcome. Why not indicate that seed propagation resulted in a complex of seedlings of the species rather than the outcome of presumed hybridization? The probability of the progeny originating from a species seems at least as acceptable as would be the probability of hybrid origin.
Some cultivars have been designated from vegetatively propagated Taxus. Unlike most plants, Taxus cuttings continue the habit of growth determined by the position the cutting had on the parent plant. It seems reasonable that within a collection of cuttings there could be a potential of phenotypic variation just because of where the cuttings were taken, and thus a nursery field could show variable plants, but certainly not because of hybrid variation. And who is to say that some cuttings or plants of designated cultivars may have been mixed up in propagation or planting and thus show a variant or two in a nursery field? Still another possibility is a branch mutation that was collected in cutting propagation. Certainly, all of these factors could be traced back to genetic parentage of already existing cultivars vs. a hybrid possibility.
Some nurserymen reported endless variation from seed propagation; others said there was much similarity in plants propagated from seed. From my understanding of hybridization, I have a hard time substantiating a hybrid if a plant comes true from seed propagation as Hatfield speculated of Taxus x hunnewelliana.
In addition to explaining the variability of progeny due to gene segregation of seed-propagated plants, branch mutation, or branch orientation of vegetatively propagated plants, there is also the possibility of variation due to soil-fertility levels, soil types, or just plain poor stand of seedling or "runt of the litter."
Commercial nurseries have in the past and, to a large extent, still today propagate Taxus cuspidata var. capitata from seed imported from Japan. It is the conclusion of this author that this selection should be designated as a botanial variety rather than the cultivar designation that is indicated in the nursery trade. The late nurseryman Laddie J. Mitiska grew his stock of Taxus cuspidata 'Capitata' from a single isolated plant of Taxus cuspidata and produced very uniform plants (Mitiska, 1954). Since Taxus is dioecious, the pollen had to come from some other plant, no matter how isolated it was. Taxus is wind-pollinated, and pollen can carry a great distance. The variety has the same plant form that is described for the species. It seems that it would be more significant to the nursery trade if the variety designation was used rather than the species. The Zelenka Nursery Company of Grand Haven, Michigan, still produces the var. capitata in great numbers from seed the company receives from Japan.
Bailey, L. H. 1933. The Cultivated Conifers in North America. The Macmillan Company. New York, N.Y.
Chadwick, L. D. and R. A. Keen. 1976. A Study of the Genus Taxus. Ohio Agricultural Research and Development Center. Research Bulletin 1086. May.
Cochran, K. D. 1991. Report of interviews with various former employees of the Hicks Nursery - Ester Emory, Alfred Hicks, Carl Alm, Willet Titus, Earl Good, and Peter Costich.
Cochran, K. D. 1991-92. Discussion with various people in reference to the naming of Taxus cultivars, including Steve Hetz, Neil Hetz, Ralph Shugert, Larry Kobel, Charles Kobel, Dan Studebaker, and Bruce Vanicek.
Hatfield, T. D. 1921. Raising Yews from Seed at Wellesley. The Garden Magazine. March 33:23-26.
Hatfield, T. D. 1929. Yews. American Plant Propagators Association. July 16.
Klehm, H. 1929. Introduction of Mr. T. D. Hatfield. American Plant Propagators Association. July 16.
Mitiska, L. J. 1954. The Propagation of Taxus by Seeds. Plant Propagators Society. Fourth Annual Meeting. December 2-4.
Wing, A. S. 1943. Henry Hicks, Missionary. Nature Magazine. December.