Cephalotaxus: The Plum Yews

Kim E. Tripp

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

Wilson was describing the surprisingly largespecimens of Cephalotaxus harringtonia he hadseen growing in Kyushu, Japan. Although it wasWilson who introduced the plant into cultiva-tion in the United States, he was not the firstWestern plant explorer to collect it and extoll itsbeauties. Long before, around 1829, the promi-nent plant collector and principal author ofFlora Japonica, Philipp Franz von Siebold, hadsent Cephalotaxus to Europe where it was re-ceived with interest and appreciation.2 Sieboldgrew five different Cephalotaxus in his owngarden in Japan, along with many other plantshe had discovered, cultivating them for theirbeauty and for evaluation as garden plants.

Today, although plum yews are widely con-sidered some of the most beautiful and useful of

evergreen conifers, their potential as ornamen-tal and medicinal plants has yet to be fullyexplored and utilized. The endangered statusof Cephalotaxus in the wild-particularly inChina, its "distribution center and refuge,"3where it is vulnerable to the increasing demandsof an exploding human population-lends asense of urgency to efforts to learn moreabout this fascinating genus. At the ArnoldArboretum, we are working to help conserveCephalotaxus while continuing to study andpropagate the genus for use in cultivation.

CephalotaxusThe modern natural range of Cephalotaxus hasdiminished considerably from that of its early

antecedents. Now the genus is restricted tosouthern and eastern Asia-Japan, Korea, south,central, and eastern China, Hainan, Taiwan,India, Burma, Laos, and parts of Vietnam.4Cephalotaxus was also found in Europe andnorthwestern North America in the Mioceneand Pliocene eras; moreover, during the Jurassicera its antecedents extended into what is nowGreenland.s

Because Japanese plum yew has been in culti-vation in Europe and the United States forclose to a century, many modern horticultur-ists are familiar with the Japanese speciesCephalotaxus harringtonia, named in honor ofthe Earl of Harrington, one of the first to growthe plant in a European garden. Far fewer areaware of other equally beautiful members of thegenus that were not found by Western explorersuntil the turn of the century. Six to twelve

species and botanical varieties, depending onthe taxonomist consulted, comprise an elegantgenus with an inelegant name.While today Cephalotaxus is most often con-

sidered the single genus of the coniferous

Cephalotaxaceae, it was earlier included in theTaxaceae with taxads like Torreya, Taxus, andPseudotaxus.~ Distinctive aspects of the em-

bryogeny and development of Cephalotaxus setit apart from this group, however, in spite ofshared adult morphological characteristics likefleshy seed coats, two-ranked needles of similarshape, and low shrub to small tree habits.’ A fewmodern authors include Amentotaxus in the

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

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

Cephalotaxaceae, resulting in occasional refer-ences in the literature to two genera in theCephalotaxaceae.8Plum yew’s botanical name is apt. "Cephalo-

taxus" means "head-yew," from the Greek"kephale" for head and the botanical name"taxus" for the yew genus. "Head-yew" refers tothe flowering structures that are borne in tightclusters or "heads" and to its needles, which re-semble those of yew. Another, more appealingcommon name, plum yew, refers to the plum-like shape and color of the ripened fleshy"cone."

Cephalotaxus is most often found growing asshrubs or small trees in soils rich in humus inmoist subtropical or warm-temperate forests,generally as understory plants in at least lightshade. They are primarily low- to mid-altitudeplants, but a few variant types are found athigher elevations and on chalky gravel cliffs.The entire range of the genus, however, extendsfrom tropical to cool temperate climates, andcold hardiness of cultivated taxa corresponds toprovenance.

While the foliage of plum yews generally re-sembles that of true yews, the reproductive stro-bili are quite distinct. Most of us are familiarwith the bright red (or occasionally yellow),fleshy, nonpoisonous "aril" that incompletelysurrounds the yew’s very poisonous, small,rounded seed. Fewer are likely to be familiarwith the seed of plum yew, which is signifi-cantly larger than that of yew, being about thesize and shape of an olive or very small plum(0.75 to 1.25 inches long and 0.25 to 0.75 incheswide) and completely enclosed by a thin, hardshell and an outer fleshy coat. As the seedripens, the fleshy coat changes color, maturingfrom an attractive, glaucous blue-green, througha warm cinnamon-red (hence "plum yew"), andfinally to a dull tan or purple-brown before ab-scission of the entire "cone" and/or degradationof the fleshy tissue.Male and female plum yew strobili are borne

on separate plants. Male strobili develop in flat-tened heads of numerous small clusters ofanthers, about 0.25 inches in diameter, regularlyarranged in the axils of the needles along the

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length of the branchlets. Female strobili developas clusters of six to twelve ovules in pairs heldon an odd-looking, oval, initially mauve-coloredhead (or "cone"), that expands from about 0.5inches in length at first visibility to the maturelength of 0.5-1.25 inches (depending on the spe-cies). Usually only one seed matures per head.9Three to five female heads are borne on stalks ator near the end of the current or previous year’sbranchlets.’° Female cones are wind pollinated.

Seeds of Cephalotaxus have a relatively longperiod of development. Depending on speciesand region, pollen cones require nine to elevenmonths to mature (from initiation to pollendispersal), while female cones can take as longas twenty-one months, generally maturingat the end of the second growing season afterinitiation."

Cephalotaxus is now rare and endangered insignificant areas of its range.’2 Its lengthy seedmaturation period, combined with a dioeciousreproductive habit and an often sparse naturaldistribution throughout much of its range, maycontribute to the seemingly low frequency ofregeneration for the genus in the wild. Accord-ing to Huang, animals and birds may also eat theseed.’3 There is also pressure on Cephalotaxusfrom human activity. It is harvested for timberin various parts of its range as well as usedfor firewood and for medicinal purposes. Thefemale cones are sometimes collected for theoil expressed from the seed. 14

Ironically, increasing awareness of the endan-gered status of Cephalotaxus comes at a timewhen its potential value has expanded beyondhorticultural uses to include anticancer com-

pounds found in its seed and vegetative tissues.Experimental work with the ester alkaloidscephalotaxme, harringtonine, and allied chemi-cals has shown promise, although apparently nowidespread therapeutic applications have yetbeen introduced.’S Sadly, two of the three spe-cies that are especially rich sources of thesealkaloids, C. hainanensis and C. oliveri, arecurrently endangered, although the third, C.fortunei, is less vulnerable.’6

Cephalotaxus as a Garden PlantThe various taxa of Cephalotaxus are of interestand value not only as endangered sources of

useful materials, but as exquisitely beautifulevergreens for a variety of modern landscapes,combining graceful habits and foliage with thetough stress resistance and ease of maintenancerequired by modern gardeners and landscapecontractors.

Cephalotaxus are slow-growing conifers withdark olive to black-green foliage. Because theirhabits range from upright and shrubby to lowand informally mounding, they can serve ashedges, masses, groundcovers, specimens, andfoundation or container plants. They thrive ina variety of soils, including extremely denseclays. They are not only tolerant of shade but-with only one exception-perform well evenin heavy shade, an unusual trait for a needledevergreen. Indeed, most Cephalotaxus producethe best foliage when given at least some shade,although some maintain excellent foliage colorin either full sun or shade.Plum yews are extraordinarily heat tolerant

in humid climates, another unusual trait for aneedled evergreen. For this reason, they havebeen called "the yew of the south," althoughthey can serve as excellent landscape plants inan area extending far beyond the Southeast.Once established, they are tolerant of extendeddry periods such as those experienced duringmost of our eastern summers. However, theyare not good choices for hot, dry climates likethose in much of the southwestern UnitedStates.

Cephalotaxus are relatively deer resistant (Ihave come to believe that no evergreen is totallydeerproof). Deer feeding on plum yews havebeen reported in areas with very heavy deerpopulations (for example, central New Jerseyand Pennsylvania). Even in these cases, how-ever, with only one exception, deer turned toCephalotaxus foliage only as a last resort.

Nomenclature and TaxonomyUnfortunately, there is no current monographon Cephalotaxus available. This is especiallytroublesome since the nomenclature of this

genus is particularly confusmg and is likely toremain a challenge for the foreseeable future; tothe best of my knowledge, no taxonomic mono-graph of the entire genus is currently underway.Hence, one must simply dive in and make a first

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attempt at creating some order out of the chaos.Key characters listed in the literature have

rarely been useful to me when dealing withplum yews. I have observed that widely citedkey characters such as stomatal band whiteness,length and shape of needle, and bark color canvary with age of the plant and the microenviron-ment in which it is grown." Full sun, cooltemperatures, and leaf maturity, for example,appear to promote whiteness of the stomatalbands on plants of the four species now grown inNorth America. In another case, an oft-cited,characteristic V-shaped trough formed by theangle at which needles are held-which hasbeen used to separate what is now called C.harringtonia var. drupaceae from the rest of thespecies’a-can frequently be seen on plants ofvarious species.

What this translates to on a practical basis isthat confirmed provenances and commercialsources are critical when working both withspecies and with cultivars. In the case of species,identifying individual plants is especially chal-lenging because the key characters are mostlymorphological intergrades. Therefore, knowl-edge of geographic origin is important, and evenwhen armed with such knowledge only themorphological extremes of the genus (e.g., C.fortunei with very long needles versus theshorter-needled C. harringtonia) can be reliablyand consistently separated from each otherex situ. Judging from what I have observed ondiverse live plants and herbarium specimens, apragmatic taxonomist might argue for includingmuch of the genus in a single species, at least forplants found on the Asian mainland. The fol-

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

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lowing discussion of forms offers a brief intro-duction to the diversity of plum yews.

Cephalotaxus fortunei Hooker(Fortune’s plum yew, San-chien-shan,Lo-han-shu, three-pointed fir)Fortune’s plum yew is native to China, where inaddition to wild populations, it is found plantednear shrines and temples. This species has awidespread range in central and eastern Chinasouth of the Yellow River and has been collectedin Shui-sa-pa (the "Water Fir Grove" near theborder of Hubei and Sichuan provinces) as partof the Metasequoia flora. 19 It was introduced toboth Europe (around 1849) and the United States(around 1858) by Robert Fortune, who collectedit in China.2°The needles of Cephalotaxus fortunei are the

longest of the genus, varying from two to overfour inches; the most dramatically long-needledplants are the most elegant. Needle diameterranges from extremely slender (1/16th inch) tonearly as wide as that of other species ( 1 /6thinch), with color of the stomatal bands on theundersides of the needles varymg from brightwhite to green. Bark is reddish-brown to darkbrown and peels in plates as plants age. Maturefemale cones are longer (one-and-a-half to twoinches) and often narrower than those of otherspecies.Cephalotaxus fortunei is a multistemmed

shrub or small tree with an open, looselyrounded habit and slightly pendant branchlets.Height and spread will vary with provenance ofseedlings and the climate in which the plantsare grown. In China, depending on locale, C.fortunei is found as a shrub or as a small tomedium-sized, multitrunked tree reachingheights in the range of thirty feet.

In Europe and North America, warmer re-gions give faster, more upright growth, whilecooler temperatures lead to shrubbier, slower-growing plants. All of the C. fortunei selectionsI have seen do best in shade, which results in amore open habit than is found in sunny situa-

tions ; in North America, full sun usually causesat least some winter burn on the foliage. Theyprefer moist, loamy soil, but will also stand upto heavy clays if grown in light shade. They arereliably cold hardy through zone 7, and in shel-

tered, shaded sites, into the warmer parts ofzone 6.

Cephalotaxus fortunei var. alpina Li is alow form found in the mountainous forests ofnorthwestern Yunnan and western Sichuan. C.

fortunei ’Grandis’ is an especially long-needledfemale form, originally from Hillier Nurseries.C. fortunei ’Lion’s Plume’ is yet another long-needled cultivar, originally received in the1950s at the Willowwood Arboretum in New

Jersey but no longer in the collections there.C. fortunei ’Prostrate Spreader’ (’Prostrata’)is a long-needled, low, mounding form, alsofrom Hillier Nurseries, with lovely dark-greenfoliage; several other prostrate selections avail-able in the United States may or may not beclones of the Hillier Nurseries plant.

Cephalotaxus griffithii Hooker(Griffith’s plum yew)Griffith’s plum yew is one of the species foundin India, specifically in the Mishmi Hills ofAssam (at about 6000 feet) where it is a smalltree fifteen to thirty feet in height. It is alsofound in western Sichuan, China. Needles aretwo to three inches long by 1/8th inch wide.Herbarium specimens of this species appearsimilar to those of the geographically overlap-ping species C. mannii, C. oliveri, and C.sinensis.zl In the past, C. griffithii was culti-vated at Kew, which received specimens fromthe Calcutta Botanical Garden sometime before

1890,zz but Kew’s inventory does not currentlylist this species. I have not seen it in cultivationanywhere in the United States. Cold hardinessof this species outside of Asia is unknown.

Cephalotaxus hainanensis Li(Hainan plum yew)Hainan plum yew is a tropical species found onthe island of Hainan, China. Some authors in-clude this taxon as part of C. mannii, which ap-pears to be its closest relative. On Hainan, it cangrow to tree size, reaching fifty to seventy feetin height. Needles are long and slender (two orthree inches by 1/8th inch); most herbariumspecimens appear nearly identical to those of C.mannii except for a greater variability in needlelength. Because of timbering and bark stripping,Hainan plum yew is seriously threatened in its

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natural range; it is also one of the species rich inanticarcinogenic alkaloids. It is not in cultiva-tion in this country but is likely to be cold hardyonly into zone 9.

Cephalotaxus harringtonia (Forbes) Koch(Harrington’s plum yew, Japanese plum yew,Inugaya)This was the first plum yew to be collected byWesterners and has been longest in Western cul-tivation. It is widespread in Japan from Kyushunorth to Hokkaido and is also found in areas ofnortheastern China and Korea. In the warmerparts of its range it is usually seen as a smalltree; in colder areas it most often appears as arounded shrub of low to medium height. It isthis latter habit that most frequently developsin cultivation in Europe and North America. Itsneedles are relatively short and often wider thanthose of mainland taxa (one-to-two inches longand 1/6th inch wide), and its fruits are rounded-ovoid. The numerous cultivars have a variety ofshapes, sizes, and foliage variegations.

Siebold first sent this plant to the LeidenBotanical Garden in 1829 as Cephalotaxusdrupaceae. Most modern authors separate C.harringtonia var. drupaceae from typical C.harringtonia. The primary difference appears tolie in the arrangement of the needles on thestem. In the literature, both historical andmodern, the foliage of C. harringtonia var.drupaceae is repeatedly described as distinctivein its upright V-formation, but I have seen thischaracteristic on any number of Cephalotaxusspecies and cultivars in diverse sites. In NorthAmerica (and in a brief survey of southernEngland), the V-shaped character appears to bemore closely related to cultural conditions andto the stage of development of the needles andplants than to any consistent taxon-specificmorphological 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-bearingstrobili expand in the needle axils and appear topromote "lifting" of the two-ranked needlesinto a V-shaped trough. The degree of "V" alsoincreases somewhat throughout the seasonon all plants of various species as leavesmature and in response to dry periods. I have

The V-shaped foliage that is attributed to

Cephalotaxus harringtoma var drupaceae can

actually be seen m other species as well. Seen herem profile, from top to bottom, C. koreana, C.

fortunei, and C. sinensis exhibit varying degrees ofthis same characteristic

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Amass of mne Cephalotaxus koreana seedlmgs at the Arnold Arboretum has provcm itselr to be excepuonullyhandsome and durable.

had no success separating what is calledC. harringtonia var. drupaceae from C.

harringtonia in North America by relyingon these morphological characteristics. Coldhardiness and landscape performance of C.harringtonia vary with cultivar and botanicalvariety as noted below.Cephalotaxus harringtonia var. nana Nakai

(Hai-inugaya) is the variety found growingon seaside cliffs and mountamous areas ofHokkaido and eastern Honshu.23 Its needles areshorter and more slender than those of C.

harringtonia, and the plants themselves areshorter, with a more upright, suckering habit.Its fruits are also smaller. In the wild, C.

harringtonia var. nana spreads by layering;it does the same in cultivation, albeit slowly.Overall it is more compact and more finely tex-tured than the species and retains this habit incultivation. Plants grown from collections made

by Spongberg and Weaver have been cold hardy

in zone 6 at the Arnold Arboretum where foliagecolor remains attractive throughout the winterin the shade but bronzes heavily in full sun.24C. harringtonia var. nana has a distinctively de-mure character in the landscape, and it wouldmake a lovely small evergreen for shaded sites.

Cephalotaxus harringtonia ’Duke Gardens’ isa broadly rounded, dense shrub reaching aboutsix feet by six feet in about ten years, dependingon where it is grown. It was selected at Sarah P.Duke Gardens at Duke University in NorthCarolina. It makes a beautiful mass in sun orshade in zones 7 to 9 and thrives in soils fromsandy loams to clays.Cephalotaxus harringtonia ’Fastigiata’ is a

distinctive upright cultivar with dark greenneedles whorled around the stem m a bottle-brush manner. ’Fastigiata’ grows even moreslowly than the average Cephalotaxus, retain-mg its broad columnar habit for the first ten totwelve years before beginning to spread into a

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The bold fohage of Cephalotaxus koreana remams black-green and glossy even in winter.

multibranched, upright mound. It does best inpart shade; full shade causes it to open up andbecome untidy, while full sun can result inwinter burn in severe years. ’Fastigiata’ is reli-ably cold hardy through zone 6 and much ofzone 5, especially in walled gardens and othersemiprotected areas, but it will suffer fromsnow and ice damage in severe winters. C.harringtonia ’Fastigiata Aurea’ is nearly identi-cal to ’Fastigiata’ except that its needle marginsare gold.

Cephalotaxus harringtonia ’Fritz Huber’ is alow-spreading cultivar with stiffer branches anda stiffer habit than other low-mounding types.Its needles are a brighter, more emerald greenthan other selections. C. harringtonia ’Gnome’is a dwarf, rounded mound growing to two feetin height, with light green foliage and shorter,stiffer needles than the species. It is a striking,impish little plant from Hillier Nurseries.C. harringtonia ’Korean Gold’ (’Ogon’, ’OgonChosen Maki’~zs is identical to ’Fastigiata’

except that new growth emerges bright yellow-gold in spring and fades to green in summer.Also, its growth is slower than that of

’Fastigiata’. ’Korean Gold’ is very effective inthe spring garden.The name Cephalotaxus harringtonia

’Prostrata’ is generally applied in this country toany and all selections with a low-spreading,low-mounding habit-plants often have some-what pendant branchlets as well. However, itshould, at this time, be used only for the HillierNurseries selection.2~ (See "A Plethora of’Prostrata’s" on page 35.) The true Hillier Nurs-eries cultivar ’Prostrata’ is especially tolerant offull sun and shows no foliar burn in the north-eastern United States, where other forms doburn. With its particularly pleasing, informallyirregular, cloudlike silhouette, it is one of themost beautiful and useful selections of plumyew available to gardeners. Its quality was re-cently recognized by the Pennsylvania Horticul-tural Society with a Gold Medal Award. There is

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a reliably named, exceptionally handsome oldplanting of C. harringtonia ’Prostrata’ at theBrooklyn Botanic Garden.

Cephalotaxus koreana Nakai(Korean plum yew)Korean plum yew is found at low to middle el-evations in Korea, northern and central Japan,and northeastern China. It is an upright, slow-growing shrub with broad, relatively coarse,black-green needles (about two inches by 1/6thinch). Plants will reach eight to ten feet in asmany years, with a narrow spread. Its densebranching and foliage cover make this speciesone of the most effective for massing. It retainsits remarkably beautiful black-green foliagethroughout the entire year, even in an exposedwinter site at the Arnold Arboretum (zone 6)where other species have bronzed heavily. Coldhardiness will vary with provenance, but C.koreana is hardy at least through zone 6 andlikely into zone 5. Further collections from thecoldest parts of its range would be desirable.

Cephalotaxus lanceolata FengC. lanceolata is known from only a few placesin northwestern Yunnan Province. It closelyresembles C. fortunei; indeed, the majority ofherbarium specimens are practically indistin-guishable from those of C. fortunei. Its needlesare long and slender (about three inches by I/8thinch) and often with needle edges that are dis-tinctly parallel up to a sharply acute apex (asopposed to tapering more gradually to an acumi-nate apex). Chinese authors distinguished thisspecies from C. fortunei on the basis of itswider, thinner needles with sharper apices(hence its name, lanceolata).z’

Cephalotaxus mannii Hooker(Mann plum yew)This species grows into a tree of about seventyfeet in height. It is the southernmost taxon andcan be found at low to middle elevations onmoist, shaded slopes and gullies in woodlands insouthern China, northeastern Burma, India,Laos, and Vietnam (and Hainan if one includesC. hainanensis within C. mannii). C. mannii issparsely distributed and seriously endangered byharvesting for timber and for medicinal pur-

poses. Its foliage as seen in illustrations and onherbarium specimens is slender, gracefullytapering, and variable in length;28 even in a driedstate it is strikingly beautiful. C. mannii is notin cultivation in the United States and is notlikely to be cold hardy north of zone 9. It isexciting to learn that the Royal Botanic Gardenat Edinburgh has recently acquired cuttings ofthis species for propagation.

Cephalotaxus oliveri Masters(Oliver plum yew)The foliage of this species is among the mostdistinctive of the genus with short, broadneedles (one or one-and-a-half inch by 1/6th

The distinctive foliage of Cephalotaxus olivem is wellillustrated in this figure from The Gardener’sChronicle (Apnl 1903), m which "the leaves aredisposed, hke the teeth of a comb."

"

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inch) arranged in two militarily precise, nearlyoverlapping ranks. The needles are pectinate,that is, arranged "like the teeth of a comb";29this trait remains distinctive even on diverseherbarium specimens. C. oliveri is a large shrubor small tree reaching ten to fifteen feet. It issometimes found in drier, cooler areas than theother subtropical species of China, but is gener-ally found growing at middle elevations in cen-tral, south central, and southwestern China,eastern India, and northern Vietnam. It wasonce in cultivation at Kew but is no longerlisted in their inventory. It is not in cultiva-tion in this country, but it might be a usefulhorticultural species thanks to its occurrencein somewhat drier and colder areas than other

subtropical taxa, as well as because of itsdistinctive foliage and its moderate size. C.oliveri is an endangered species and is rich inanticarcinogenic alkaloids.

Cephalotaxus sinensis (Rehder and Wilson) Li(Chinese plum yew)Currently also known as C. harringtonia var.sinensis and historically as C. drupaceae var.sinensis, this is another very widespread spe-cies. It is a medium-sized, somewhat open androunded shrub with slender, medium-lengthneedles (about two inches by 1/8th inch). It willeventually reach ten to twelve feet in heightwith half the spread. It occurs naturally in moistwoodlands and thickets on limestone slopesthroughout eastern, central, and northwesternChina, including Sichuan and Yunnan prov-inces. This species was first collected for theWest and brought to the United States byWilson as C. drupaceae var. sinensis; Rehderlater changed the name to C. harringtonia var.sinensis and Li ultimately elevated it to C.sinensis.3° Plants are generally cold hardythrough zone 6; they may suffer winter burnin exposed sites but have held up well to iceand snow in Boston. C. sinensis makes a lovelyevergreen shrub in appropriately shaded sites,where it contributes an elegant, yet informalornamental character.

Cephalotaxus wilsoniana Hayata(Wilson plum yew, Taiwan plum yew)This species is endemic to Taiwan, being widelybut sparsely distributed in diverse woodlands at

middle elevations.31 It is a medium-sized tree,growing to thirty feet with pendant branches. Itsneedles tend to be slender and of moderate

length (about two inches by 1/8th inch). In theUnited States, it is likely be cold hardy intozone 8. C. wilsoniana is in cultivation at Kewand the Royal Botanic Garden at Edinburgh, butit is not in this country.

Propagation ,

My work with four of the most hardy speciesand several cultivars indicates that similar

propagation techniques are likely to apply to allCephalotaxus.32 Propagation from seed or cut-tings is quite a long process. Seed gives bestgermination after ten to twelve weeks of coldstratification and after removal of the fleshyseed coat (which, unlike the similarly con-structed Ginkgo, is usually only very slightlymalodorous). Seeds that have overwintered out-doors under the mother plants give reasonablegermination results as well. Even in a warmgreenhouse, seedlings take a worrisome lengthof time to completely emerge, and it is particu-larly important to maintain consistently moder-ate moisture during this period. One is temptedto conjecture that this slow seedling emergencemay contribute to the apparently low regenera-tion rate of Cephalotaxus in the wild.33

Propagation from stem cuttings is not diffi-cult, but it too is slow. In the northeasternUnited States, four- to six-inch stem cuttingscan be successfully rooted throughout the yearonce the spring flush has been completed andfoliage has hardened off somewhat (betweenJuly and March). In the southeastern UnitedStates, cuttings root best when taken during fallor winter (October to February), avoiding thepeak heat of the summer. Stem cuttings willroot even without rooting hormones, but mod-erate concentrations result in slightly larger,fuller root systems. With bottom heat, cuttingsgenerally take about four months to develop aviable root system, although they can take aslong as six months in low light. Heavily flower-ing branches from male plants should beavoided since profuse flowering competes withdeveloping roots, and male flowers are a havenfor fungal spores. Flowers on female shoots, onthe other hand, have little effect on rooting anddo not cause fungal problems. Informal observa-

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A Plethora of ’Prostrata’sThere is great confusion in the trade over plum yew selections with low, creeping,horizontally spreading or prostrate growth habits. A plethora of prostrate forms havebeen propagated and given names like variety prostrata, forma prostrata, or cultivar’Prostrata’, ’Prostrate Form’, or ’Prostrate Spreader’. Most of these prostrate forms arean 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 soyoung plants grow horizontally for many years. Eventually, such plants will develop atleast one upright leader and will begin to grow as an upright shrub or small tree, as mostseedlings do in nature. It can take anywhere from three to thirty years for plants grownfrom lateral branch cuttings to develop a leader, depending on growing conditions andcharacteristics of the parent plant. Historically, many plants have been used as sourcesof cuttings for these prostrate forms. Thus, two individual prostrate plants, both, forexample, with the botanical name prostrata may have been propagated from two verydifferent parent plants. One, both, or neither of the parent plants, however, may havebeen 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 inthe mid-1900s when the botanical designations forma and varietas were uncriticallytranslated 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 implyclonal parentage.2 This has become a particular problem with prostrate plum yews.3 Forexample, Hillier Nurseries now lists their exceptional selection of prostrate Japaneseplum yew as cultivar ’Prostrata’.4 Unfortunately, that cultivar name has been indis-criminately applied in this country to many other plants propagated from the lateralbranches of random parent plants, which may or may not have been propagated fromclones of the Hillier plant. Horticulturists desiring all of the exceptional qualitiesassociated with the Royal Horticultural Society’s Gold Medal Award-winning C.harringtonia ’Prostrata’ must look for plants produced from clonal propagations ofthe 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 theresulting propagules ’Prostrata’, regardless of parentage /or quality of the plant), has led to greatconfusion 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 analtitude of 4000 feet near Wa-shan, Chma, September, 1908.

37

tions in the eastern United States indicate thatterminal cuttings are slower to root than lateralones, sometimes needing an additional two tofour weeks; these will, however, result in plantswith upright growth. Lateral cuttings, whilequicker to root, result in plants with prostrategrowth, at least for a number of years. For someas yet unexplained reason, ’Duke Gardens’ hasbeen more difficult to root than other cultivars.The only challenge in propagating this genus

is the degree of patience required. It would beworth experimenting with fog systems to see ifthey might hasten the process of rooting. Janicket al. reported success with micropropagation ofC. harringtoma,34 but to the best of my knowl-edge no one has yet applied the technique on acommercial scale.

Cephalotaxus at the Arnold ArboretumThe Arnold Arboretum has had a long and sig-nificant relationship with Cephalotaxus, havingbeen among the first to collect and cultivate the

genus in this country. Several men made impor-tant collections of Cephalotaxus for the Arbore-tum, among them Frank Meyer, William

Purdom, Joseph Rock, and Charles Sargent;however, the many collections made by E. H.Wilson included some of the most interesting.In Japan, Wilson collected C. harringtonia,C. harringtonia var. nana, and C. koreana. InChma, he collected C. fortunei, C. harringtonia,and C. oliveri, and was the first Westernerto collect what would eventually be namedC. sinensis. Throughout his collecting yearshe consistently expressed an interest in thegenus. Both Wilson and Alfred Rehder workedon describing and naming the genus over manyyears.3sWhile none of the Wilson-era accessions

or their progeny survive at the Arnold, theArboretum remains actively interested in

Cephalotaxus, and its living collections arehome to one of the country’s most diverse col-lections of source-documented, wild-collectedgermplasm. Among others, Stephen Spongberghas collected material in China, Japan, andKorea. The most recent collections of Cephalo-taxus for the Arboretum were made by PeterDel Tredici in China last year. We are especiallypleased to have new germplasm of C. sinensis

collected by Peter from the northerly portionof its range, which may offer improved cold har-diness and winter performance in the winterlandscape.

Cephalotaxus was once an integral part of theprehistoric, indigenous flora of both NorthAmerica and Asia. This genus has long sincedisappeared in North America and is now seri-ously endangered in Asia, yet plum yews areamong the most interesting, beautiful, and use-ful of evergreen conifers. Cephalotaxus war-rants increased study and conservation-withrespect for its importance as both a wild andcultivated conifer.

AcknowledgmentsThe author gratefully acknowledges Shiu-ying Hu fortranslation and interpretation of texts from relevantChmese systematic references, and smcerely thanks JackAlexander, Allen J. Coombes, Peter Del Tredici, MichaelDirr, Al)os Far~on, Martm Gardner, Richard Hartlage,Andrew Knoll, Gary Koller, Cynthia Osman, M.D.,Stephen Spongberg, Chris Strand, Bemto Tan, Tom Ward,and Elizabeth Wheeler for critical discussion, usefulinformation, or helpful suggestions.

Kim E. Tripp is a Putnam Fellow at the Arnold Arbo-retum, usmg the living collections for research, teaching,and writing.

Notes1 E H. Wilson, The Comfers and Taxads of Japan(Cambridge: Publications of the Arnold Arboretum,University Press, 1916), v-viri, 6-9.

2 P. F. von Siebold and J G. Zuccanm, Flora Japomca(1835). ~.

3 L. K. Fu, "A study on the genus Cephalotaxus Sieb. etZucc.," Acta Phytotaxonomica Smca (1984~ 22(4/:277-288.

4 J. T. Buchholz, "Genenc and subgenenc distributionof the comferales," Botamcal Gazette ( 1948) 110( 1 /~80-91; W. C. Cheng, Sylva Smca /Berjrng: EditonalCommitee of Flora of Woody Plants of Chma, 1983), ),379-385; W. C Cheng, L. K. Fu, and C. S. Chao,"Cephalotaxaceae, Cephalotaxus, " Flora RezpubhcaePopulans Smicae, tomus 7 (Beijing: Science Press,1978), 422-436; H. H Hu, "Distribution of taxads andconifers in Chma," Proc 5 Pacif Sci Congr (1934~ 4:3273-3288; S. Y. Hu, "Cephalotaxaceae," m "Noteson the Flora of Chma IV," Taiwama ( 1964~ 10: 13-62,25-31; S. C. Lee, "Distribution of Woody Plants ofChma," Taiwama (1963) 9: 11-21; T. B. Lee (TchangBok Yi), Illustrated Flora of Korea (Seoul:Hyangmunsa, 1979), 58; H. L. Li., Woody Flora ofTaiwan (Narbeth, PA: Livingston, 1963), 38-39; H. L.Li, "New species and varieties in Cephalotaxus,

"

38

Lloydia (1953) 16(3): 162-164, H. L. Li, "Presentdistribution and habitats of the conifers and taxads,"Evolution (1953) 7: 245-261; J. Ohwi, Flora of Japan(Washington, D.C.: Smithsoman Institution, 1965),111; A. Steward, Manual of Vascular Plants of theLower Yangtze Valley of Chma (Corvalhs: OregonState College, 1958), 61-62.

5 R. Flomn, "The distnbution of conifer and taxadgenera m time and space," Acta Horu Bergiana ( 1963)20/4/: 121-326.

6 See, for example, A. Rehder and E. H. Wilson,"Cephalotaxus," Plantae Wilsonianae, vol. II, ed. C.S. Sargent (Cambridge: Harvard University Press,1916), 3-6. The exact position of Cephalotaxushas been argued back and forth since Neger placedit as a smgle genus in its own family m 1907(Die Nadelholzer (KomferenJ und ubngenGymnospermen, Leipzig[, which was contrary to A.W. Eichler’s original placement within the Taxaceae("Coniferae" in A Engler and K. Prantl’s DieNaturhchen Pflanzenfamihen, Leipzig, 1889).

~ Sigmficant differences m the embryogeny anddevelopment of Cephalotaxus from the taxads andother comfers were reported by J. T. Buchholz ("Theembryogeny of Cephalotaxus Fortunel," Bulletm ofthe Torrey Botamcal Club [1925] 52[6]: 311-322) butwere most definitively elucidated by H. Singh ("Thelife history and systematic position of Cephalotaxusdrupaceae Sieb. et Zucc.," Phytomorphology [1961]11: 153-197), whose work m this area has remained astandard reference for modern authors treating the

group.8 As, for example, m C. N. Page’s "Cephalotaxaceae,"The Famihes and Genera of Vascular Plants. 1

Ptendophytes and Gymnosperms, ed K. U. Kramerand P. S. Green (Berlin & NY: Springer-Verlag, 1990),299-302; and m The New Royal HorticulturalSociety Dictionary of Gardening (New York:Stockton Press, 1992), 569.

9 K. R. Sporne, The Morphology of Gymnosperms(U.K.: Hutchmson, 1965).

10 Page, op. cit.11 H. Singh, op. cit.12 A. Far~on, C. Page, and N. Schellevis, "A prelimmaryworld list of threatened conifer taxa," Biodiversityand Conservation (1993[ 2: 304-326.

13 Q. Huang, "Cephalotaxus mannm Hook. f.," ChmaPlant Red Data Book-Rare and Endangered Plants,vol. I, ed. L. K. Fu and J. M. Jm (Beijing. Science Press,1992), 24-25.

la Throughout the Cephalotaxus literature, both oldand new, there are recurring references to destructionof its habitat due to pressure from humans-bothfrom general activity, like forestry, and fromharvesting of the Cephalotaxus itself for vamouspurposes. E. H. Wilson noted the use of the seed as anoil source m Japan (op. cit., p. 7). Barry Ymger, afterseveral trips to Korea, reported the generaldestruction of populations of C. koreana by clear-cutting ("Notes on Cephalotaxus, the plum yew,"

Bull Amencan Comfer Society [1989] 6(3): 57-59). Ina 1988 pubhcation, Zou Shou-qmg reported that theforest cover of Xishuangbanna prefecture was cutfrom 60% to 33% over the prior twenty years andhsts C. olmem as one of the endangered relict speciesthere ("The vulnerable and endangered plants ofXishuangbanna prefecture, Yunnan provmce, Chma"Arnoldia [1988] 48(2): 3-7) Both Cephalotaxusspecies listed in the Chma Plant Red Data Bookare reported to be threatened by lumbermg, andC mannm is also reported to be endangered byharvesting for use as a medicinal herb (see Q. Huang,"Cephalotaxus mannn Hook. f," and Z. C. Luo et al.,"Cephalotaxus olmem Mast." m the Chma Plant RedData Book, 24-27).

~5 The importance of Cephalotaxus has expandedbeyond horticulture to include potential use as asource of anticancer compounds found m its

tissues (C. R. Smith, R. G. Powell and K. L.

Mikolajczak, "The genus Cephalotaxus, source

of homoharnngtonine and related anticancer

alkaloids," Cancer Treatment Rpt [1976] 60:

1157-1170). The ester alkaloids cephalotaxme,harrmgtonrne, and allied chemicals have shownsignificant antitumor activity m a number of m vitrostudies, and there are recent reports of phase I chmcaltrials (pharmacokinetic) (see D. M. Graifer et al.,"Effect of alkaloids of the Cephalotaxus group on theelongation of the polypeptide cham on humannbosomes," Molecular Biology [1991] 24(G/: 1344-1350), and phase II clinical tnals (therapeutic) onhuman subjects as well (see C. T. Tan et al., in CancerTreatment Reports [1987] 71 1245-48, cited m E. R.Wickremesinhe and R. Arteca, "Establishment offast-growmg callus and root cultures of Cephalotaxusharrmgtoma," Plant Cell Reports 12 [1993], 80-83/.Other recent publications indicate that progress hasbeen made m development of separation (see D. G.Cai et al., "Semipreparative separation of alkaloidsfrom Cephalotaxus fortunei Hook f. by high-speedcountercurrent chromatography," Journal LiqmdChromatography [ 1992] 15: 2873-2881) and syntheticproduction systems for cephalotaxmes and

harnngtonines (see T. P. Burkholder and P. L. Fuchs,"Total synthesis of the Cephalotaxus alkaloidsdl-cephalotaxme, dl-11-hydroxycephalotaxine, anddl-drupacme," journal Amencan Chemical Society[ 1990] 112: 9601-9613; and M. Ikeda et al., "Syntheticstudies on Cephalotaxus alkaloids. A synthesis of(=/-cephalotaxme," Chemical and PharmaceuticalBulletm [1993] 41(2): 276-281), as well as

improvements on Cephalotaxus tissue proliferationtechniques (see P. J. Westgate et al., "Approximationof continuous growth of Cephalotaxus harrmgtomaplant cell cultures using fed-batch operation,"Biotechnology and Bioengmeermg [1991] 38: 241-246 ; and E. R. Wickremesinhe and R Arteca, op. cit.)

1~ T. P Chu, "A study of the alkaloids m Cephalotaxusand their bearing on the chemotaxonomic problemsof the genus," Acta Phytotaxonomica Sinica (1979)17[4/: 7-20.

39

1~ The primary conifer references, such as Krussman’s1976 (1984 translation) Manual of CultivatedComfers (Portland, OR: Timber Press, 66-69), pl. 63,and Humphrey Welch’s 1990 The Comfer Manual,vol. I (Netherlands: Kluwer Academic) 191-194, relyon these often tenuous, morphological characters todistinguish Cephalotaxus taxa.

18 A specific example of such a tenuous morphologicaltrait used to distinguish a taxon is the "V" outlinesupposedly created by the fohage of C. harnngtomavar. drupaceae, which has been cited by manyprominent references to separate C harnngtoma var.drupaceae from other Cephalotaxus In reality, thistrait can be seen on many plants of Cephalotaxusregardless of species-see, for example, W. J. Bean,Trees and Shrubs Hardy m the Bntzsh Isles (England:John Murray, 1950), 405-406; P Den Ouden and B. K.Boom, Manual of Cultivated Comfers (The Hague:Martinus Nijhoff, 1965), 65-69; Hillier Nurseries,The Hilher Manual of Trees and Shrubs, 6th ed.(Devon, England: David and Charles, 1991), 584-585, 677, 679; G Krussman, op. cit ; J Lewis,"Cephalotaxaceae," The European Garden Flora,vol. I, ed. S. M. Walters et al. (London: CambridgeUniversity Press, 1986), 73-74; and H. J. Welch,op. cit.

19 S. Y. Hu, "The Metasequoia flora and its

phytogeographic sigmficance," Journal of the ArnoldArboretum (1980) 61: 41-94.

20 Interestingly, Fortune collected this species and sentit back to the USDA as part of a shipment of materialcollected on an expedition m search of the best formsof tea plants (Camelha smensis) (see R. Gardener,"Robert Fortune and the cultivation of tea in theUmted States," Arnoldia ( 1971 ~ 31 ( 1 /: 1-18 This wasa fortuitous opportumty to mclude Cephalotaxus aspart of the collections.

21 In fact, C. olmem was originally confounded with Cgrzffithzi Oliver’s 1890 illustration of C. gmffithn wasC olmen (see D. Oliver, "Cephalotaxus griffithii,"

"

p1.1933, Hooker’s Icones Plantarum, vol. X, pt. I, 3rdseries, J. D. Hooker, 1890) This was later clarified byMasters (see The Gardener’s Chronicle [1903] 850:226-228). /.

z2 J. D. Hooker, Flora of Bntish India, vol. V (London,1890), 647-648.

23 As reported by J. Ohwi in the 1965 Flora of Tapan(Washtngton, D. C.: Smtthsoman Instttution~, p. Ill,and as observed by S. Spongberg when travelingm Japan.

za For notes on collections made during the Spongbergand Weaver expedition to Japan and Korea, see S A.Spongberg, "Korean Adventure," Arnoldia (1978)38(4~: 132-152, and S. A. Spongberg and R. E. Weaver,Jr., "Collecting expedition to Japan and Korea,"Aznoldza ( 1978~ 38/ 1 28-31

zs ’Korean Gold’ was descnbed in C. Hahn and B.

Yinger, "Cultivars of Japanese plants at BrooksideGardens," Arnoldia (1983) 43/4/. 3-19.

26 Hillier Nurseries, op. cit.

27 See, for example, the primary reference, W. C Chenget al., op. cit.

28 Pl. 1523 m J. D. Hooker’s "Cephalotaxus mannm" "

~op. cit., 1890) shows the elegant character of thisfoliage beautifully. Hooker remarks in the

accompanying text on C mannm, "A very distinct

species ... but so hke Taxus baccata as to be easilymistaken for it." Recall the elegant, gracefullytapering outline of English yew, and you willunderstand the companson.

z9 M. T. Masters, op. cit.~° Alfred Rehder in the 1941 article, "New species,

varieties and combmations from the herbarium andthe collections of the Arnold Arboretum" (Journal ofthe Arnold Arboretum 22: 569-571) changed thename of what had been called C drupaceae to C.harrmgtoma ~he concluded that harnngtoma was theolder of the two specific epithets), and hence, all ofthe included botamcal varieties became C.

harringtonia Subsequently, H. L. Li, m his 1953article, "New species and varieties m Cephalotaxus,

"

elevated it to the species C smensis.31 H L. Li, 1963, op. cit.32 For further information on propagation of Cephalo-

taxus, see M A. Dirr and C. W. Heuser, Jr., TheReference Manual of Woody Plant Propagation~Athens, GA: Varsity Press, 1987/, 104, A. Fordhamand L. Spraker, "Propagation manual of selected gym-nosperms," Arnoldia 1977/ 37/ 1 /: 48; and J. A. Youngand C. G Young, Seeds of Woody Plants in NorthAmerica (Portland, OR: Dioscorides Press, 1992), 93.

33 Huang, op. cit., cites a naturally low pollination rate,and Luo et al., op. cit, report infrequent regeneration,but neither source cites other work m support ofthese statements. It is possible that a combination ofdioecious reproductive biology, relatively slow seedmaturation and germination, seed predation by birdsand mammals, increasingly sparse distribution ofmature plants, and general destruction of habitatfavorable for seedling survival and development,leads to the reported infrequent regeneration ofCephalotaxus

34 J. Jamck et al., "Micropropagation of Cephalotaxusharringtoma," HortScience (1994) 29/2/: 120-122.

35 For details of taxa collected on specific expeditionsand early taxonomic commentary on various taxa,see A. Rehder, "Enumeration of the ligneous plants ofnorthern China," Journal of the Arnold Arboretum(1923) 4~3/: 117-128; A. Rehder, "New species,vane ties and combinations from the herbarium andthe collections of the Arnold Arboretum," Journal ofthe Arnold Arboretum (1923) 4. 107; A. Rehder and EH. Wilson, "Enumeration of ligneous plants collectedby J. F Rock on the Arnold Arboretum expedition tonorthwestern Chma and northeastern Tibet," Journalof the Arnold Arboretum (1928) 9~ 5-20; A. Rehderand E. H. Wilson, "Cephalotaxus"; E H. Wilson,"The taxads and conifers of Yunnan," Journal of theArnold Arboretum (1926) 7’ 39-68, and E. H. Wilson,The Comfers and Taxads of Japan, op. cit.