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Home , Amentotaxus, Cephalotaxaceae, Cephalotaxus, Cephalotaxus fortunei, Cephalotaxus griffithii, Cephalotaxus hainanensis

Cephalotaxus: The Plum Yews

Kim E. Tripp

The largest ~Japanese plum yews] I grow in the rich forests at the foot of Higashi-Kirishima ... I saw many from 8 to 10 m tall with ... wide-spreading branches forming broad rounded crowns. Such trees, with their dark-green pale or glaucescent on the under side, are very beautiful.... E. H. Wilson, The and Taxads of , 1916’

Wilson was describing the surprisingly large antecedents. Now the genus is restricted to specimens of harringtonia he had southern and eastern -Japan, Korea, south, seen growing in Kyushu, Japan. Although it was central, and eastern , Hainan, Taiwan, Wilson who introduced the into cultiva- , Burma, Laos, and parts of Vietnam.4 tion in the , he was not the first Cephalotaxus was also found in Europe and Western plant explorer to collect it and extoll its northwestern in the beauties. Long before, around 1829, the promi- and eras; moreover, during the nent plant collector and principal author of era its antecedents extended into what is now Flora Japonica, Philipp Franz von Siebold, had Greenland.s sent Cephalotaxus to Europe where it was re- Because Japanese plum yew has been in culti- ceived with interest and appreciation.2 Siebold vation in Europe and the United States for grew five different Cephalotaxus in his own close to a century, many modern horticultur- garden in Japan, along with many other ists are familiar with the Japanese he had discovered, cultivating them for their Cephalotaxus harringtonia, named in honor of beauty and for evaluation as garden plants. the Earl of Harrington, one of the first to grow Today, although plum yews are widely con- the plant in a European garden. Far fewer are sidered some of the most beautiful and useful of aware of other equally beautiful members of the conifers, their potential as ornamen- genus that were not found by Western explorers tal and medicinal plants has yet to be fully until the turn of the century. Six to twelve explored and utilized. The endangered status species and botanical varieties, depending on of Cephalotaxus in the wild-particularly in the taxonomist consulted, comprise an elegant China, its "distribution center and refuge,"3 genus with an inelegant name. where it is vulnerable to the increasing demands While today Cephalotaxus is most often con- of an exploding human population-lends a sidered the single genus of the coniferous sense of urgency to efforts to learn more , it was earlier included in the about this fascinating genus. At the Arnold with taxads like , , and Arboretum, we are working to help conserve Pseudotaxus.~ Distinctive aspects of the em- Cephalotaxus while continuing to study and bryogeny and development of Cephalotaxus set propagate the genus for use in cultivation. it apart from this group, however, in spite of shared adult morphological characteristics like Cephalotaxus fleshy coats, two-ranked needles of similar The modern natural range of Cephalotaxus has shape, and low to small habits.’ A few diminished considerably from that of its early modern authors include in the

Cephalotaxus sinensis, seen here "d la mode" m last winter’s ice storm, is one of the most cold hardy of the Chmese plum-yew species. 26

The mature frmts of Cephalotaxus (C. sinensis is shown here) resemble olmes or small plums.

Cephalotaxaceae, resulting in occasional refer- While the foliage of plum yews generally re- ences in the literature to two genera in the sembles that of true yews, the reproductive stro- Cephalotaxaceae.8 bili are quite distinct. Most of us are familiar Plum yew’s botanical name is apt. "Cephalo- with the bright (or occasionally yellow), taxus" means "head-yew," from the Greek fleshy, nonpoisonous "aril" that incompletely "kephale" for head and the botanical name surrounds the yew’s very poisonous, small, "taxus" for the yew genus. "Head-yew" refers to rounded seed. Fewer are likely to be familiar the flowering structures that are borne in tight with the seed of plum yew, which is signifi- clusters or "heads" and to its needles, which re- cantly larger than that of yew, being about the semble those of yew. Another, more appealing size and shape of an olive or very small plum common name, plum yew, refers to the plum- (0.75 to 1.25 inches long and 0.25 to 0.75 inches like shape and color of the ripened fleshy wide) and completely enclosed by a thin, hard "cone." shell and an outer fleshy coat. As the seed Cephalotaxus is most often found growing as ripens, the fleshy coat changes color, maturing or small trees in soils rich in humus in from an attractive, glaucous blue-green, through moist subtropical or warm-temperate forests, a warm cinnamon-red (hence "plum yew"), and generally as understory plants in at least light finally to a dull tan or purple-brown before ab- shade. They are primarily low- to mid-altitude scission of the entire "cone" and/or degradation plants, but a few variant types are found at of the fleshy tissue. higher elevations and on chalky gravel cliffs. Male and female plum yew strobili are borne The entire range of the genus, however, extends on separate plants. Male strobili develop in flat- from tropical to cool temperate climates, and tened heads of numerous small clusters of cold hardiness of cultivated taxa corresponds to anthers, about 0.25 inches in diameter, regularly provenance. arranged in the axils of the needles along the 27

length of the branchlets. Female strobili develop useful materials, but as exquisitely beautiful as clusters of six to twelve ovules in pairs held for a variety of modern landscapes, on an odd-looking, oval, initially mauve-colored combining graceful habits and foliage with the head (or "cone"), that expands from about 0.5 tough stress resistance and ease of maintenance inches in length at first visibility to the mature required by modern gardeners and landscape length of 0.5-1.25 inches (depending on the spe- contractors. cies). Usually only one seed matures per head.9 Cephalotaxus are slow-growing conifers with Three to five female heads are borne on stalks at dark olive to black-green foliage. Because their or near the end of the current or previous year’s habits range from upright and shrubby to low branchlets.’° Female cones are wind pollinated. and informally mounding, they can serve as of Cephalotaxus have a relatively long hedges, masses, groundcovers, specimens, and period of development. Depending on species foundation or container plants. They thrive in and region, cones require nine to eleven a variety of soils, including extremely dense months to mature (from initiation to pollen clays. They are not only tolerant of shade but- dispersal), while female cones can take as long with only one exception-perform well even as twenty-one months, generally maturing in heavy shade, an unusual trait for a needled at the end of the second growing season after evergreen. Indeed, most Cephalotaxus produce initiation." the best foliage when given at least some shade, Cephalotaxus is now rare and endangered in although some maintain excellent foliage color significant areas of its range.’2 Its lengthy seed in either full sun or shade. maturation period, combined with a dioecious Plum yews are extraordinarily heat tolerant reproductive habit and an often sparse natural in humid climates, another unusual trait for a distribution throughout much of its range, may needled evergreen. For this reason, they have contribute to the seemingly low frequency of been called "the yew of the south," although regeneration for the genus in the wild. Accord- they can serve as excellent landscape plants in ing to Huang, and may also eat the an area extending far beyond the Southeast. seed.’3 There is also pressure on Cephalotaxus Once established, they are tolerant of extended from human activity. It is harvested for timber dry periods such as those experienced during in various parts of its range as well as used most of our eastern summers. However, they for firewood and for medicinal purposes. The are not good choices for hot, dry climates like female cones are sometimes collected for the those in much of the southwestern United oil expressed from the seed. 14 States. Ironically, increasing awareness of the endan- Cephalotaxus are relatively deer resistant (I gered status of Cephalotaxus comes at a time have come to believe that no evergreen is totally when its potential value has expanded beyond deerproof). Deer feeding on plum yews have horticultural uses to include anticancer com- been reported in areas with very heavy deer pounds found in its seed and vegetative tissues. populations (for example, central New Jersey Experimental work with the ester alkaloids and Pennsylvania). Even in these cases, how- cephalotaxme, harringtonine, and allied chemi- ever, with only one exception, deer turned to cals has shown promise, although apparently no Cephalotaxus foliage only as a last resort. widespread therapeutic applications have yet Nomenclature and been introduced.’S Sadly, two of the three spe- cies that are especially rich sources of these Unfortunately, there is no current monograph alkaloids, C. hainanensis and C. oliveri, are on Cephalotaxus available. This is especially currently endangered, although the third, C. troublesome since the nomenclature of this fortunei, is less vulnerable.’6 genus is particularly confusmg and is likely to remain a challenge for the foreseeable future; to as a Garden Plant Cephalotaxus the best of my knowledge, no taxonomic mono- The various taxa of Cephalotaxus are of interest graph of the entire genus is currently underway. and value not only as endangered sources of Hence, one must simply dive in and make a first 28

attempt at creating some order out of the chaos. What this translates to on a practical basis is Key characters listed in the literature have that confirmed provenances and commercial rarely been useful to me when dealing with sources are critical when working both with plum yews. I have observed that widely cited species and with . In the case of species, key characters such as stomatal band whiteness, identifying individual plants is especially chal- length and shape of needle, and bark color can lenging because the key characters are mostly vary with age of the plant and the microenviron- morphological intergrades. Therefore, knowl- ment in which it is grown." Full sun, cool edge of geographic origin is important, and even temperatures, and maturity, for example, when armed with such knowledge only the appear to promote whiteness of the stomatal morphological extremes of the genus (e.g., C. bands on plants of the four species now grown in fortunei with very long needles versus the North America. In another case, an oft-cited, shorter-needled C. harringtonia) can be reliably characteristic V-shaped trough formed by the and consistently separated from each other angle at which needles are held-which has ex situ. Judging from what I have observed on been used to separate what is now called C. diverse live plants and herbarium specimens, a harringtonia var. drupaceae from the rest of the pragmatic taxonomist might argue for including species’a-can frequently be seen on plants of much of the genus in a single species, at least for various species. plants found on the Asian mainland. The fol-

Needle length vanes widely among plum yew species. (IeftJ has the longest needles, while C. harrrngtoma (lower right), m general, has the shortest. Other species, hke C. smensis (upper mght), are intermediate. 29

lowing discussion of forms offers a brief intro- tered, shaded sites, into the warmer parts of duction to the diversity of plum yews. zone 6. Cephalotaxus fortunei var. alpina Li is a Cephalotaxus fortunei Hooker low form found in the mountainous forests of (Fortune’s plum yew, San-chien-shan, northwestern Yunnan and western Sichuan. C. Lo-han-shu, three-pointed ) fortunei ’Grandis’ is an especially long-needled Fortune’s plum yew is native to China, where in female form, originally from Hillier Nurseries. addition to wild populations, it is found planted C. fortunei ’Lion’s Plume’ is yet another long- near shrines and temples. This species has a needled , originally received in the widespread range in central and eastern China 1950s at the Willowwood Arboretum in New south of the Yellow River and has been collected Jersey but no longer in the collections there. in Shui-sa-pa (the "Water Fir Grove" near the C. fortunei ’Prostrate Spreader’ (’Prostrata’) border of Hubei and Sichuan provinces) as part is a long-needled, low, mounding form, also of the Metasequoia flora. 19 It was introduced to from Hillier Nurseries, with lovely dark-green both Europe (around 1849) and the United States foliage; several other prostrate selections avail- (around 1858) by Robert Fortune, who collected able in the United States may or may not be it in China.2° clones of the Hillier Nurseries plant. The needles of Cephalotaxus fortunei are the Hooker longest of the genus, varying from two to over four inches; the most dramatically long-needled (Griffith’s plum yew) plants are the most elegant. Needle diameter Griffith’s plum yew is one of the species found ranges from extremely slender (1/16th inch) to in India, specifically in the Mishmi Hills of nearly as wide as that of other species ( 1 /6th Assam (at about 6000 feet) where it is a small inch), with color of the stomatal bands on the tree fifteen to thirty feet in height. It is also undersides of the needles varymg from bright found in western Sichuan, China. Needles are white to green. Bark is reddish-brown to dark two to three inches long by 1/8th inch wide. brown and peels in plates as plants age. Mature Herbarium specimens of this species appear female cones are longer (one-and-a-half to two similar to those of the geographically overlap- inches) and often narrower than those of other ping species C. mannii, C. oliveri, and C. species. sinensis.zl In the past, C. griffithii was culti- Cephalotaxus fortunei is a multistemmed vated at Kew, which received specimens from shrub or small tree with an open, loosely the Calcutta Botanical Garden sometime before rounded habit and slightly pendant branchlets. 1890,zz but Kew’s inventory does not currently Height and spread will vary with provenance of list this species. I have not seen it in cultivation seedlings and the climate in which the plants anywhere in the United States. Cold hardiness are grown. In China, depending on locale, C. of this species outside of Asia is unknown. fortunei is found as a shrub or as a small to hainanensis Li medium-sized, multitrunked tree reaching Cephalotaxus heights in the range of thirty feet. (Hainan plum yew) In Europe and North America, warmer re- Hainan plum yew is a tropical species found on gions give faster, more upright growth, while the island of Hainan, China. Some authors in- cooler temperatures lead to shrubbier, slower- clude this taxon as part of C. mannii, which ap- growing plants. All of the C. fortunei selections to be its closest relative. On Hainan, it can I have seen do best in shade, which results in a grow to tree size, reaching fifty to seventy feet more open habit than is found in sunny situa- in height. Needles are long and slender (two or tions ; in North America, full sun usually causes three inches by 1/8th inch); most herbarium at least some winter burn on the foliage. They specimens appear nearly identical to those of C. prefer moist, loamy soil, but will also stand up mannii except for a greater variability in needle to heavy clays if grown in light shade. They are length. Because of timbering and bark stripping, reliably cold hardy through zone 7, and in shel- Hainan plum yew is seriously threatened in its 30

natural range; it is also one of the species rich in anticarcinogenic alkaloids. It is not in cultiva- tion in this country but is likely to be cold hardy only into zone 9. Cephalotaxus harringtonia (Forbes) Koch (Harrington’s plum yew, Japanese plum yew, Inugaya) This was the first plum yew to be collected by Westerners and has been longest in Western cul- tivation. It is widespread in Japan from Kyushu north to Hokkaido and is also found in areas of northeastern China and Korea. In the warmer parts of its range it is usually seen as a small tree; in colder areas it most often appears as a rounded shrub of low to medium height. It is this latter habit that most frequently develops in cultivation in Europe and North America. Its needles are relatively short and often wider than those of mainland taxa (one-to-two inches long and 1/6th inch wide), and its are rounded- ovoid. The numerous cultivars have a variety of shapes, sizes, and foliage variegations. Siebold first sent this plant to the Leiden Botanical Garden in 1829 as Cephalotaxus drupaceae. Most modern authors separate C. harringtonia var. drupaceae from typical C. harringtonia. The primary difference appears to lie in the arrangement of the needles on the stem. In the literature, both historical and modern, the foliage of C. harringtonia var. drupaceae is repeatedly described as distinctive in its upright V-formation, but I have seen this characteristic on any number of Cephalotaxus species and cultivars in diverse sites. In North America (and in a brief survey of southern England), the V-shaped character appears to be more closely related to cultural conditions and to the stage of development of the needles and plants than to any consistent taxon-specific morphological trait. This V-shaped characteris- tic becomes especially pronounced on the flow- ering branches of many male Cephalotaxus, regardless of species or variety, as pollen-bearing strobili expand in the needle axils and appear to promote "lifting" of the two-ranked needles The V-shaped foliage that is attributed to Cephalotaxus harringtoma var drupaceae can into a V-shaped trough. The degree of "V" also actually be seen m other species as well. Seen here increases somewhat the season throughout m profile, from top to bottom, C. koreana, C. on all plants of various species as leaves fortunei, and C. sinensis exhibit varying degrees of mature and in response to dry periods. I have this same characteristic 31

Amass of mne seedlmgs at the Arnold Arboretum has provcm itselr to be excepuonully handsome and durable. had no success separating what is called in zone 6 at the Arnold Arboretum where foliage C. harringtonia var. drupaceae from C. color remains attractive throughout the winter harringtonia in North America by relying in the shade but bronzes heavily in full sun.24 on these morphological characteristics. Cold C. harringtonia var. nana has a distinctively de- hardiness and landscape performance of C. mure character in the landscape, and it would harringtonia vary with cultivar and botanical make a lovely small evergreen for shaded sites. variety as noted below. Cephalotaxus harringtonia ’Duke Gardens’ is Cephalotaxus harringtonia var. nana Nakai a broadly rounded, dense shrub reaching about (Hai-inugaya) is the variety found growing six feet by six feet in about ten years, depending on seaside cliffs and mountamous areas of on where it is grown. It was selected at Sarah P. Hokkaido and eastern Honshu.23 Its needles are Duke Gardens at Duke University in North shorter and more slender than those of C. Carolina. It makes a beautiful mass in sun or harringtonia, and the plants themselves are shade in zones 7 to 9 and thrives in soils from shorter, with a more upright, suckering habit. sandy loams to clays. Its fruits are also smaller. In the wild, C. Cephalotaxus harringtonia ’Fastigiata’ is a harringtonia var. nana spreads by layering; distinctive upright cultivar with dark green it does the same in cultivation, albeit slowly. needles whorled around the stem m a bottle- Overall it is more compact and more finely tex- brush manner. ’Fastigiata’ grows even more tured than the species and retains this habit in slowly than the average Cephalotaxus, retain- cultivation. Plants grown from collections made mg its broad columnar habit for the first ten to by Spongberg and Weaver have been cold hardy twelve years before beginning to spread into a 32

The bold fohage of Cephalotaxus koreana remams black-green and glossy even in winter. multibranched, upright mound. It does best in except that new growth emerges bright yellow- part shade; full shade causes it to open up and gold in spring and fades to green in summer. become untidy, while full sun can result in Also, its growth is slower than that of winter burn in severe years. ’Fastigiata’ is reli- ’Fastigiata’. ’Korean Gold’ is very effective in ably cold hardy through zone 6 and much of the spring garden. zone 5, especially in walled gardens and other The name Cephalotaxus harringtonia semiprotected areas, but it will suffer from ’Prostrata’ is generally applied in this country to snow and ice damage in severe winters. C. any and all selections with a low-spreading, harringtonia ’Fastigiata Aurea’ is nearly identi- low-mounding habit-plants often have some- cal to ’Fastigiata’ except that its needle margins what pendant branchlets as well. However, it are gold. should, at this time, be used only for the Hillier Cephalotaxus harringtonia ’Fritz Huber’ is a Nurseries selection.2~ (See "A Plethora of low-spreading cultivar with stiffer branches and ’Prostrata’s" on page 35.) The true Hillier Nurs- a stiffer habit than other low-mounding types. eries cultivar ’Prostrata’ is especially tolerant of Its needles are a brighter, more emerald green full sun and shows no foliar burn in the north- than other selections. C. harringtonia ’Gnome’ eastern United States, where other forms do is a dwarf, rounded mound growing to two feet burn. With its particularly pleasing, informally in height, with light green foliage and shorter, irregular, cloudlike silhouette, it is one of the stiffer needles than the species. It is a striking, most beautiful and useful selections of plum impish little plant from Hillier Nurseries. yew available to gardeners. Its quality was re- C. harringtonia ’Korean Gold’ (’Ogon’, ’Ogon cently recognized by the Pennsylvania Horticul- Chosen Maki’~zs is identical to ’Fastigiata’ tural Society with a Gold Medal Award. There is 33

a reliably named, exceptionally handsome old poses. Its foliage as seen in illustrations and on planting of C. harringtonia ’Prostrata’ at the herbarium specimens is slender, gracefully Brooklyn Botanic Garden. tapering, and variable in length;28 even in a dried state it is strikingly beautiful. C. mannii is not Cephalotaxus koreana Nakai in cultivation in the United States and is not (Korean plum yew) likely to be cold hardy north of zone 9. It is Korean plum yew is found at low to middle el- exciting to learn that the Royal Botanic Garden evations in Korea, northern and central Japan, at Edinburgh has recently acquired cuttings of and northeastern China. It is an upright, slow- this species for propagation. growing shrub with broad, relatively coarse, black-green needles (about two inches by 1/6th Masters inch). Plants will reach eight to ten feet in as (Oliver plum yew) many years, with a narrow spread. Its dense The foliage of this species is among the most branching and foliage cover make this species distinctive of the genus with short, broad one of the most effective for massing. It retains needles (one or one-and-a-half inch by 1/6th its remarkably beautiful black-green foliage throughout the entire year, even in an exposed winter site at the Arnold Arboretum (zone 6) where other species have bronzed heavily. Cold hardiness will vary with provenance, but C. koreana is hardy at least through zone 6 and likely into zone 5. Further collections from the coldest parts of its range would be desirable. Cephalotaxus lanceolata Feng C. lanceolata is known from only a few places in northwestern Yunnan Province. It closely resembles C. fortunei; indeed, the majority of herbarium specimens are practically indistin- guishable from those of C. fortunei. Its needles are long and slender (about three inches by I/8th inch) and often with needle edges that are dis- tinctly parallel up to a sharply acute apex (as opposed to tapering more gradually to an acumi- nate apex). Chinese authors distinguished this species from C. fortunei on the basis of its wider, thinner needles with sharper apices (hence its name, lanceolata).z’ Hooker (Mann plum yew) This species grows into a tree of about seventy feet in height. It is the southernmost taxon and can be found at low to middle elevations on moist, shaded slopes and gullies in woodlands in southern China, northeastern Burma, India, Laos, and Vietnam (and Hainan if one includes The distinctive of olivem is well C. hainanensis within C. C. foliage Cephalotaxus mannii). mannii is illustrated in this figure from The Gardener’s distributed and sparsely seriously endangered by Chronicle (Apnl 1903), m which "the leaves are " harvesting for timber and for medicinal pur- disposed, hke the teeth ofa comb." 34

inch) arranged in two militarily precise, nearly middle elevations.31 It is a medium-sized tree, overlapping ranks. The needles are pectinate, growing to thirty feet with pendant branches. Its that is, arranged "like the teeth of a comb";29 needles tend to be slender and of moderate this trait remains distinctive even on diverse length (about two inches by 1/8th inch). In the herbarium specimens. C. oliveri is a large shrub United States, it is likely be cold hardy into or small tree reaching ten to fifteen feet. It is zone 8. C. wilsoniana is in cultivation at Kew sometimes found in drier, cooler areas than the and the Royal Botanic Garden at Edinburgh, but other subtropical species of China, but is gener- it is not in this country. ally found growing at middle elevations in cen- tral, south central, and southwestern China, Propagation , work with four of the most eastern and northern Vietnam. It was My hardy species India, and several cultivars indicates that similar once in cultivation at Kew but is no longer are to to all listed in their inventory. It is not in cultiva- propagation techniques likely apply from seed or cut- tion in this country, but it might be a useful Cephalotaxus.32 Propagation is a process. Seed gives best horticultural species thanks to its occurrence tings quite long after ten to twelve weeks of cold in somewhat drier and colder areas than other germination stratification and after removal of the fleshy subtropical taxa, as well as because of its seed coat unlike the con- distinctive foliage and its moderate size. C. (which, similarly structed Ginkgo, is usually only very slightly oliveri is an endangered species and is rich in Seeds that have overwintered out- anticarcinogenic alkaloids. malodorous). doors under the mother plants give reasonable (Rehder and Wilson) Li germination results as well. Even in a warm (Chinese plum yew) greenhouse, seedlings take a worrisome length of time to and it is Currently also known as C. harringtonia var. completely emerge, particu- maintain moder- sinensis and historically as C. drupaceae var. larly important to consistently ate moisture this One is sinensis, this is another very widespread spe- during period. tempted to that this slow cies. It is a medium-sized, somewhat open and conjecture seedling emergence rounded shrub with slender, medium-length may contribute to the apparently low regenera- in the wild.33 needles (about two inches by 1/8th inch). It will tion rate of Cephalotaxus not diffi- eventually reach ten to twelve feet in height Propagation from stem cuttings is but it too is slow. In the northeastern with half the spread. It occurs naturally in moist cult, four- to six-inch stem woodlands and thickets on limestone slopes United States, cuttings throughout eastern, central, and northwestern can be successfully rooted throughout the year once has been and China, including Sichuan and Yunnan prov- the spring flush completed has hardened off somewhat inces. This species was first collected for the foliage (between West and brought to the United States by July and March). In the southeastern United root best when taken fall Wilson as C. drupaceae var. sinensis; Rehder States, cuttings during or winter to the later changed the name to C. harringtonia var. (October February), avoiding sinensis and Li ultimately elevated it to C. peak heat of the summer. Stem cuttings will root even without but mod- sinensis.3° Plants are generally cold hardy rooting hormones, concentrations result in through zone 6; they may suffer winter burn erate slightly larger, root With bottom in exposed sites but have held up well to ice fuller systems. heat, cuttings four months to a and snow in Boston. C. sinensis makes a lovely generally take about develop can take as evergreen shrub in appropriately shaded sites, viable root system, although they as months in low flower- where it contributes an elegant, yet informal long six light. Heavily ornamental character. ing branches from male plants should be avoided since profuse flowering competes with Hayata developing roots, and male flowers are a haven (Wilson plum yew, Taiwan plum yew) for fungal spores. Flowers on female shoots, on This species is endemic to Taiwan, being widely the other hand, have little effect on rooting and but sparsely distributed in diverse woodlands at do not cause fungal problems. Informal observa- 35

A Plethora of ’Prostrata’s There is great confusion in the trade over plum yew selections with low, creeping, horizontally spreading or prostrate growth habits. A plethora of prostrate forms have been propagated and given names like variety prostrata, forma prostrata, or cultivar ’Prostrata’, ’Prostrate Form’, or ’Prostrate Spreader’. Most of these prostrate forms are an artifact of propagation from stem cuttings that used lateral branches instead of ter- minal shoots. Rooted cuttings of lateral branches retain their lateral orientation, and so young plants grow horizontally for many years. Eventually, such plants will develop at least one upright leader and will begin to grow as an upright shrub or small tree, as most seedlings do in nature. It can take anywhere from three to thirty years for plants grown from lateral branch cuttings to develop a leader, depending on growing conditions and characteristics of the parent plant. Historically, many plants have been used as sources of cuttings for these prostrate forms. Thus, two individual prostrate plants, both, for example, with the botanical name prostrata may have been propagated from two very different parent plants. One, both, or neither of the parent plants, however, may have been prostrate in habit, and both parents may exhibit very different landscape charac- teristics, such as degree of cold hardiness and performance in full sun. At the turn of the century, to name a plant based on a developmental trait rather than a genetic trait was no problem because it was then correct usage. Confusion entered in the mid-1900s when the botanical designations forma and varietas were uncritically translated into cultivar names set in single quotes.’ As a result, a primary source of con- fusion is that, unlike varietas and forma, cultivar names with single quotes now imply clonal parentage.2 This has become a particular problem with prostrate plum yews.3 For example, Hillier Nurseries now lists their exceptional selection of prostrate Japanese plum yew as cultivar ’Prostrata’.4 Unfortunately, that cultivar name has been indis- criminately applied in this country to many other plants propagated from the lateral branches of random parent plants, which may or may not have been propagated from clones of the Hillier plant. Horticulturists desiring all of the exceptional qualities associated with the Royal Horticultural Society’s Gold Medal Award-winning C. harringtonia ’Prostrata’ must look for plants produced from clonal propagations of the Hillier Nurseries plant.

Notes

1 For innumerable examples, see L. H. Bailey et al., Hortus III (New York: Macmillan, 1976).

2 For further discussion of this issue with regard to comfers, see H. J. Welch, Manual of Dwarf Conifers (Little Compton, R.L~ Theophrastus, 1979), 40-48, also 151-152, 392.

3 Propagation of many different plants from lateral cuttmgs and mdiscmmmate naming of all of the resulting propagules ’Prostrata’, regardless of parentage /or quality of the plant), has led to great confusion among prostrate plum yews m the U.S. nursery trade (see K. E. Tripp, "A Plum Yew Primer,"" Amencan Nurseryman /1994) 180/9)~ 28-37). 4 Hillier Nursenes, The Hilher Manual of Trees and Shrubs, 6th ed (Devon, England: David and Charles, 1991),584-585,677,679. 36

Cephalotaxus fortunei, thirty feet high and three feet m circumference, photographed by E H Wilson at an altitude of 4000 feet near Wa-shan, Chma, September, 1908. 37

tions in the eastern United States indicate that collected by Peter from the northerly portion terminal cuttings are slower to root than lateral of its range, which may offer improved cold har- ones, sometimes needing an additional two to diness and winter performance in the winter four weeks; these will, however, result in plants landscape. with upright growth. Lateral cuttings, while Cephalotaxus was once an integral part of the quicker to root, result in plants with prostrate prehistoric, indigenous flora of both North growth, at least for a number of years. For some America and Asia. This genus has long since as yet unexplained reason, ’Duke Gardens’ has disappeared in North America and is now seri- been more difficult to root than other cultivars. ously endangered in Asia, yet plum yews are The only challenge in propagating this genus among the most interesting, beautiful, and use- is the degree of patience required. It would be ful of evergreen conifers. Cephalotaxus war- worth experimenting with fog systems to see if rants increased study and conservation-with they might hasten the process of rooting. Janick respect for its importance as both a wild and et al. reported success with micropropagation of cultivated . C. harringtoma,34 but to the best of my knowl- edge no one has yet applied the technique on a Acknowledgments commercial scale. The author gratefully acknowledges Shiu-ying Hu for translation and interpretation of texts from relevant Chmese and thanks Cephalotaxus at the Arnold Arboretum systematic references, smcerely Jack Alexander, Allen J. Coombes, Peter Del Tredici, Michael The Arnold Arboretum has had a long and sig- Dirr, Al)os Far~on, Martm Gardner, Richard Hartlage, nificant relationship with Cephalotaxus, having Andrew Knoll, Gary Koller, Cynthia Osman, M.D., Chris Bemto Tom been among the first to collect and cultivate the Stephen Spongberg, Strand, Tan, Ward, and Elizabeth Wheeler for critical discussion, useful genus in this country. Several men made impor- information, or helpful suggestions. tant collections of Cephalotaxus for the Arbore- tum, among them Frank Meyer, William Purdom, Joseph Rock, and Charles Sargent; Kim E. Tripp is a Putnam Fellow at the Arnold Arbo- however, the many collections made by E. H. retum, usmg the living collections for research, teaching, and writing. Wilson included some of the most interesting. In Japan, Wilson collected C. harringtonia, Notes C. harringtonia var. nana, and C. koreana. In 1 E H. Wilson, The Comfers and Taxads of Japan Chma, he collected C. fortunei, C. harringtonia, (Cambridge: Publications of the Arnold Arboretum, and C. oliveri, and was the first Westerner University Press, 1916), v-viri, 6-9. 2 to collect what would eventually be named P. F. von Siebold and J G. Zuccanm, Flora Japomca (1835).~. C. sinensis. Throughout his collecting years 3 L. K. Fu, "A study on the genus Cephalotaxus Sieb. et he an interest in the consistently expressed Zucc.," Acta Phytotaxonomica Smca (1984~ 22(4/: genus. Both Wilson and Alfred Rehder worked 277-288. on describing and naming the genus over many 4 J. T. Buchholz, "Genenc and subgenenc distribution years.3s of the comferales," Botamcal Gazette ( 1948) 110( 1/~ W. C. Smca Editonal While none of the Wilson-era accessions 80-91; Cheng, Sylva /Berjrng: Commitee of Flora of Woody Plants of Chma, 1983),), or their survive at the the progeny Arnold, 379-385; W. C Cheng, L. K. Fu, and C. S. Chao, Arboretum remains actively interested in "Cephalotaxaceae, Cephalotaxus, " Flora Rezpubhcae Cephalotaxus, and its living collections are Populans Smicae, tomus 7 (Beijing: Science Press, H. H "Distribution of taxads and home to one of the country’s most diverse col- 1978), 422-436; Hu, lections of wild-collected conifers in Chma," Proc 5 Pacif Sci Congr (1934~ 4: source-documented, 3273-3288; S. Y. Hu, "Cephalotaxaceae," m "Notes germplasm. Among others, Stephen Spongberg on the Flora of Chma IV," Taiwama ( 1964~ 10: 13-62, has collected material in China, Japan, and 25-31; S. C. Lee, "Distribution of Woody Plants of Korea. The most recent collections of Cephalo- Chma," Taiwama (1963) 9: 11-21; T. B. Lee (Tchang Bok Yi), Illustrated Flora of Korea taxus for the Arboretum were made Peter (Seoul: by Hyangmunsa, 1979), 58; H. L. Li., Woody Flora of Del Tredici in China last year. We are especially Taiwan (Narbeth, PA: Livingston, 1963), 38-39; H. L. pleased to have new germplasm of C. sinensis Li, "New species and varieties in Cephalotaxus," 38

Lloydia (1953) 16(3): 162-164, H. L. Li, "Present Bull Amencan Comfer Society [1989] 6(3): 57-59). In distribution and habitats of the conifers and taxads," a 1988 pubhcation, Zou Shou-qmg reported that the Evolution (1953) 7: 245-261; J. Ohwi, Flora of Japan forest cover of Xishuangbanna prefecture was cut (Washington, D.C.: Smithsoman Institution, 1965), from 60% to 33% over the prior twenty years and 111; A. Steward, Manual of Vascular Plants of the hsts C. olmem as one of the endangered relict species Lower Yangtze Valley of Chma (Corvalhs: Oregon there ("The vulnerable and endangered plants of State College, 1958), 61-62. Xishuangbanna prefecture, Yunnan provmce, Chma" 5 R. Flomn, "The distnbution of conifer and taxad Arnoldia [1988] 48(2): 3-7) Both Cephalotaxus listed in the Chma Plant Red Data Book genera m time and space," Acta Horu Bergiana ( 1963) species 20/4/: 121-326. are reported to be threatened by lumbermg, and 6 See, for example, A. Rehder and E. H. Wilson, C mannm is also reported to be endangered by "Cephalotaxus," Plantae Wilsonianae, vol. II, ed. C. harvesting for use as a medicinal herb (see Q. Huang, S. Sargent (Cambridge: Harvard University Press, "Cephalotaxus mannn Hook. f," and Z. C. Luo et al., olmem Mast." m the Chma Plant Red 1916), 3-6. The exact position of Cephalotaxus "Cephalotaxus has been argued back and forth since Neger placed Data Book, 24-27). it as a smgle genus in its own family m 1907 ~5 The importance of Cephalotaxus has expanded (Die Nadelholzer (KomferenJ und ubngen beyond horticulture to include potential use as a Gymnospermen, Leipzig[, which was contrary to A. source of anticancer compounds found m its W. Eichler’s original placement within the Taxaceae tissues (C. R. Smith, R. G. Powell and K. L. ("Coniferae" in A Engler and K. Prantl’s Die Mikolajczak, "The genus Cephalotaxus, source Naturhchen Pflanzenfamihen, Leipzig, 1889). of homoharnngtonine and related anticancer ~ Sigmficant differences m the embryogeny and alkaloids," Cancer Treatment Rpt [1976] 60: development of Cephalotaxus from the taxads and 1157-1170). The ester alkaloids cephalotaxme, other comfers were reported by J. T. Buchholz ("The harrmgtonrne, and allied chemicals have shown embryogeny of Cephalotaxus Fortunel," Bulletm of significant antitumor activity m a number of m vitro the Torrey Botamcal Club [1925] 52[6]: 311-322) but studies, and there are recent reports of phase I chmcal were most definitively elucidated by H. Singh ("The trials (pharmacokinetic) (see D. M. Graifer et al., life history and systematic position of Cephalotaxus "Effect of alkaloids of the Cephalotaxus group on the drupaceae Sieb. et Zucc.," Phytomorphology [1961] elongation of the polypeptide cham on human 11: 153-197), whose work m this area has remained a nbosomes," Molecular [1991] 24(G/: 1344- standard reference for modern authors treating the 1350), and phase II clinical tnals (therapeutic) on group. human subjects as well (see C. T. Tan et al., in Cancer 8 Treatment 71 cited m E. R. As, for example, m C. N. Page’s "Cephalotaxaceae," Reports [1987] 1245-48, The Famihes and Genera of Vascular Plants. 1 Wickremesinhe and R. Arteca, "Establishment of callus and root cultures of Ptendophytes and , ed K. U. Kramer fast-growmg Cephalotaxus and P. S. Green (Berlin & NY: Springer-Verlag, 1990), harrmgtoma," Plant Cell Reports 12 [1993], 80-83/. Other recent indicate that has 299-302; and m The New Royal Horticultural publications progress Society Dictionary of Gardening (New York: been made m development of separation (see D. G. Stockton Press, 1992), 569. Cai et al., "Semipreparative separation of alkaloids from Hook f. 9 K. R. Sporne, The Morphology of Gymnosperms Cephalotaxus fortunei by high-speed (U.K.: Hutchmson, 1965). countercurrent chromatography," Journal Liqmd Chromatography [ 1992] 15: 2873-2881) and synthetic 10 cit. Page, op. systems for and 11 production cephalotaxmes H. Singh, op. cit. harnngtonines (see T. P. Burkholder and P. L. Fuchs, 12 A. Far~on, C. Page, and N. Schellevis, "A prelimmary "Total synthesis of the Cephalotaxus alkaloids world list of threatened conifer taxa," Biodiversity dl-cephalotaxme, dl-11-hydroxycephalotaxine, and and Conservation (1993[ 2: 304-326. dl-drupacme," journal Amencan Chemical Society 13 Q. Huang, "Cephalotaxus mannm Hook. f.," Chma [ 1990] 112: 9601-9613; and M. Ikeda et al., "Synthetic Plant Red Data Book-Rare and Endangered Plants, studies on Cephalotaxus alkaloids. A synthesis of vol. I, ed. L. K. Fu and J. M. Jm (Beijing. Science Press, (=/-cephalotaxme," Chemical and Pharmaceutical 1992), 24-25. Bulletm [1993] 41(2): 276-281), as well as la Throughout the Cephalotaxus literature, both old improvements on Cephalotaxus tissue proliferation P. and new, there are recurring references to destruction techniques (see J. Westgate et al., "Approximation of continuous of of its habitat due to pressure from humans-both growth Cephalotaxus harrmgtoma from general activity, like forestry, and from plant cell cultures using fed-batch operation," and 38: 241- harvesting of the Cephalotaxus itself for vamous Biotechnology Bioengmeermg [1991] and E. R. Wickremesinhe and R purposes. E. H. Wilson noted the use of the seed as an 246 ; Arteca, op. cit.) oil source m Japan (op. cit., p. 7). Barry Ymger, after 1~ T. P Chu, "A study of the alkaloids m Cephalotaxus several trips to Korea, reported the general and their bearing on the chemotaxonomic problems destruction of populations of C. koreana by clear- of the genus," Acta Phytotaxonomica Sinica (1979) cutting ("Notes on Cephalotaxus, the plum yew," 17[4/: 7-20. 39

1~ The primary conifer references, such as Krussman’s 27 See, for example, the primary reference, W. C Cheng 1976 (1984 translation) Manual of Cultivated et al., op. cit. 28 " Comfers (Portland, OR: Timber Press, 66-69), pl. 63, Pl. 1523 m J. D. Hooker’s "Cephalotaxus mannm" and Humphrey Welch’s 1990 The Comfer Manual, ~op. cit., 1890) shows the elegant character of this vol. I (Netherlands: Kluwer Academic) 191-194, rely foliage beautifully. Hooker remarks in the on these often tenuous, morphological characters to accompanying text on C mannm, "A very distinct distinguish Cephalotaxus taxa. species ... but so hke as to be easily 18 A specific example of such a tenuous morphological mistaken for it." Recall the elegant, gracefully trait used to distinguish a taxon is the "V" outline tapering outline of English yew, and you will supposedly created by the fohage of C. harnngtoma understand the companson. var. drupaceae, which has been cited by many z9 M. T. Masters, op. cit. references to C var. prominent separate harnngtoma ~° Alfred Rehder in the 1941 article, "New species, drupaceae from other Cephalotaxus In reality, this varieties and combmations from the herbarium and trait can be seen on many plants of Cephalotaxus the collections of the Arnold Arboretum" (Journal of regardless of species-see, for example, W. J. Bean, the Arnold Arboretum 22: 569-571) changed the Trees and Shrubs m the Bntzsh Isles Hardy (England: name of what had been called C drupaceae to C. P Den Ouden and B. K. John Murray, 1950), 405-406; harrmgtoma ~he concluded that harnngtoma was the Manual Cultivated Boom, of Comfers (The Hague: older of the two specific epithets), and hence, all of Martinus Nijhoff, 1965), 65-69; Hillier Nurseries, the included botamcal varieties became C. The Hilher Manual Trees and Shrubs, 6th ed. of harringtonia Subsequently, H. L. Li, m his 1953 David and " (Devon, England: Charles, 1991), 584- article, "New species and varieties m Cephalotaxus, G 585, 677, 679; Krussman, op. cit ; J Lewis, elevated it to the species C smensis. The European Garden Flora, "Cephalotaxaceae," 31 H L. cit. vol. ed. S. M. Walters et al. Li, 1963, op. I, (London: Cambridge 32 University Press, 1986), 73-74; and H. J. Welch, For further information on propagation of Cephalo- see M A. Dirr and C. W. The op. cit. taxus, Heuser, Jr., Manual Plant 19 S. Y. "The flora and its Reference of Woody Propagation Hu, Metasequoia A. Fordham the Arnold ~Athens, GA: Varsity Press, 1987/, 104, phytogeographic sigmficance," Journal of and L. manual of selected Arboretum (1980) 61: 41-94. Spraker, "Propagation gym- nosperms," Arnoldia 1977/ 37/ 1 /: 48; and J. A. Young 20 Fortune collected this species and sent Interestingly, and C. G Young, Seeds of Woody Plants in North it back to the USDA as of a of material part shipment America (Portland, OR: Dioscorides Press, 1992), 93. collected on an m search of the best forms expedition 33 cites a low of tea plants (Camelha smensis) (see R. Gardener, Huang, op. cit., naturally pollination rate, and Luo et "Robert Fortune and the cultivation of tea in the al., op. cit, report infrequent regeneration, but neither source cites other work m of Umted States," Arnoldia ( 1971 ~ 31 ( 1 /: 1-18 This was support these statements. It is that a combination of a fortuitous opportumty to mclude Cephalotaxus as possible dioecious slow seed part of the collections. reproductive biology, relatively 21 maturation and germination, seed predation by birds In fact, C. olmem was originally confounded with C and mammals, increasingly sparse distribution of grzffithzi Oliver’s 1890 illustration of C. gmffithn was " mature and destruction of habitat C olmen D. plants, general (see Oliver, "Cephalotaxus griffithii," favorable for seedling survival and development, p1.1933, Hooker’s Icones Plantarum, vol. X, pt. I, 3rd leads to the reported infrequent regeneration of series, J. D. Hooker, 1890) This was later clarified by Masters The Gardener’s Chronicle Cephalotaxus (see [1903] 850: 34 226-228)./. J. Jamck et al., "Micropropagation of Cephalotaxus HortScience 120-122. z2 D. Flora Bntish India, vol. V harringtoma," (1994) 29/2/: J. Hooker, of (London, 35 1890), 647-648. For details of taxa collected on specific expeditions 23 and early taxonomic commentary on various taxa, As reported by J. Ohwi in the 1965 Flora of Tapan see A. Rehder, "Enumeration of the ligneous plants of (Washtngton, D. C.: Smtthsoman Instttution~, p. Ill, northern China," Journal of the Arnold Arboretum and as observed by S. Spongberg when traveling (1923) 4~3/: 117-128; A. Rehder, "New species, m Japan. za vane ties and combinations from the herbarium and For notes on collections made during the Spongberg the collections of the Arnold Arboretum," Journal of see S A. and Weaver expedition to Japan and Korea, the Arnold Arboretum 4. A. Rehder and E Arnoldia (1923) 107; Spongberg, "Korean Adventure," (1978) H. Wilson, "Enumeration of ligneous plants collected 132-152, and S. A. and R. E. Weaver, 38(4~: Spongberg by J. F Rock on the Arnold Arboretum expedition to Jr., "Collecting expedition to Japan and Korea," northwestern Chma and northeastern Tibet," Journal Aznoldza ( 1978~ 38/ 1 28-31 of the Arnold Arboretum (1928) 9~ 5-20; A. Rehder zs ’Korean Gold’ was descnbed in C. Hahn and B. and E. H. Wilson, "Cephalotaxus"; E H. Wilson, Yinger, "Cultivars of Japanese plants at Brookside "The taxads and conifers of Yunnan," Journal of the Gardens," Arnoldia (1983) 43/4/. 3-19. Arnold Arboretum (1926) 7’ 39-68, and E. H. Wilson, 26 Hillier Nurseries, op. cit. The Comfers and Taxads of Japan, op. cit.