Features galley - Gil Nelson
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GIL NELSON 30 the American Gardener M ENTION HOLLIES to most gardeners and they immedi- ately conjure images of shiny, spiny, dark green leaves, a conical form, and bright red fruits glistening in the De- cember sun. There is little doubt that the winter beauty of evergreen hollies strikes a chord with many plant lovers. But evergreens are not the only hollies worthy of our attention. Deciduous hol- lies, too, can make dramatic statements in our gardens and landscapes. Unlike some deciduous plants, whose charm diminish- es with their falling leaves, deciduous hol- lies come into their own in fall and winter, their branches festooned with showy fruits that, botanically speaking, are termed drupes. As with their evergreen cousins, their brightly colored jewelry hangs on well into winter, providing birds and squirrels with a nutritious food source. There are 11 species of deciduous hol- lies native to the United States and southeastern Canada. Some, such as winterberry (Ilex verticillata), have a very broad range. Others, such as Suwa- nee River holly (I. curtissii), are confined to a very localized habitat. All are dioe- cious, meaning that some plants are male and others female. To ensure opti- mal fruit production, gardeners need to plant both male and female selections. (For a brief description of the holly fam- ily and its origins, see the web special linked to the online version of this arti- cle at www.ahs.org.) WINTERBERRY The most popular and widely grown na- tive holly is winterberry (I. verticillata, USDA Hardiness Zones 3–9, AHS Heat Zones 9–1). A wetland species in nature, winterberry is found predominantly along streams and at the edges of bogs, pocosins, floodplains, and swampy woods from Canada to northernmost Florida and west to Louisiana. It is much more common in the northeast than the Deep South and is one of the hardier deciduous hollies. Nev- ertheless, it readily adapts to garden soils and at least some hardy selections perform deciduous native Hollies BY GIL NELSON Even after shedding their leaves, these hollies shine in the fall and winter garden. This is the first of a two-part series by Gil Nelson; evergreen native hollies will be featured in the November/December issue.
Transcript of Features galley - Gil Nelson
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AL T H O U G H B E S T L O V E D fortheir clusters of fall and winterberries that appeal to both gar-
deners and wildlife, evergreen holliesmake a substantial statement in the gar-den throughout the year. And severalNorth American species and selectionsare among the most stunning of the lot.
The holly family (Aquifoliaceae) isconsidered by most taxonomists to bemonotypic, meaning that all of its
species are contained within a singlegenus—in this case, Ilex. There areabout 400 holly species worldwide, and17 or so are indigenous to North Amer-ica, distributed throughout the easternhalf of the continent from New Englandto the southern tip of the Florida penin-sula and west to Minnesota and Texas.Eight of these are evergreen, mostlyranging in the wild from Virginia toLouisiana.
AMERICAN HOLLYOf the red- or yellow-fruited evergreenhollies native to the United States, theAmerican holly (Ilex opaca, USDA Hardi-ness Zones 5–9, AHS Heat Zones 9–5) isprobably the best known and most widelydistributed. Because of its similarity to thehighly valued English holly (I. aquifolium),this was likely one of the first Americantrees to catch the attention of early Britishcolonists. Its hallmark appearance is a com-
Second of a two-part series on hollies native to North America; deciduous hollies were covered in the September/October issue.
America’sEvergreen Hollies
BY GIL NELSON
From leaves and bark to berries, these native evergreens offer four seasons of landscape appeal.
America’sEvergreen Hollies
BY GIL NELSON
bination of glossy, dark green, spiny leaves,bright red fruit, and attractive grayish bark.The availability of hundreds—perhapsthousands—of named cultivars and selec-tions attests to the American holly’s en-during popularity.
“We sell about 30 Ilex opaca cultivarshere in Baltimore,” says Bill Kuhl ofMcLean Nurseries, a well-known Mary-land garden center that has specialized inpropagating and growing hollies since
1946. “Everything we sell is one of my fa-vorites, but ‘Dan Fenton’, ‘Jersey Princess’,‘Miss Helen’, and ‘Satyr Hill’ stand out.”‘Satyr Hill’ earned recognition as theHolly Society of America (HSA) 2003Holly of the Year.
Mature American hollies growing innatural habitats tend to be pyramidal inshape with an open crown. The lowerbranches usually fall off naturally, allowinga clear view of the smooth, grayish, and
mottled bark. Cultivated specimens, espe-cially those grown in sunny locations, areoften more compact, with branching near-ly to ground level. Southern trees—thosefrom the Carolinas southward—averageabout 50 feet tall at maturity, but can betwice this height in optimal conditions;northern trees are often somewhat shorter.
Female trees produce conspicuousclusters of bright red fruit that contrastsharply with the dark green leaves. The
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FLOWERS, FRUIT, AND POLLINATIONHollies are textbook examples of a dioecious species—onewhose flowers are functionally unisexual and borne on sepa-rate individuals.
The female flowers contain an obvious superior ovary, usu-ally surrounded by several reduced, clearly non-functional sta-mens. The plump ovary is typically topped by a short, thickstyle and a flattened, buttonlike stigma, although in somespecies the style is absent and the sticky stigma sits directlyatop the ovary.
Typical male flowers have prominent stamens with con-spicuous pollen-filled anthers surrounding a diminutive ovarythat in some species aborts early, leaving a tiny cavity in thecenter of the flower. Male plants seem to produce more flow-ers per cluster and are often showier in the spring than fe-male plants, but only females produce the colorful fruits forwhich hollies are best known.
Gardeners who value winter fruit should plant mostly fe-male selections, adding a few males to ensure pollination.
Where native hollies are relatively abundant in nearby wood-lands or neighboring yards, additional male plants may notbe needed for abundant fruit production. In landscapes de-void of other native hollies, however, planting one male forevery five or six females is the suggested ratio.
For maximum pollination and fruiting, it is usually best toplant male and female plants of the same species. Hollies,however, tend to be somewhat promiscuous. Male plants ofone species might contribute pollen to female plants of an-other species if flowering times overlap—especially if thetwo are closely related.
The fruits of the hollies are commonly called berries, or de-scribed as “berrylike.” But in botanical terms, they are moreaccurately considered drupes. Berries are defined as fleshyfruits with a skinlike covering (exocarp) surrounding a juicypulp (mesocarp) that contains naked seeds. In a drupe, theseed is protected by a hard, bony structure called an endocarp.
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Opposite page: This mature specimen of the cultivar ‘Merry Christmas’ illustrates American holly’s attractive pyramidal shape. Above: Manyother selections of American holly are available, including the popular red-fruited ‘Jersey Princess’, left, and yellow-fruited ‘Canary’, right.
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best of the red-fruited female cultivars in-clude ‘Old Heavy Berry’, ‘Satyr Hill’, and‘Vera’. As many as 50 yellow-fruited selec-tions are available, including ‘Canary’,‘Oak Grove’, ‘Fire Chief ’, and ‘Fallaw’, aswell as I. opaca forma xanthocarpa.
Selections like ‘Slim Jane’, a red-fruitedfemale, and the yellow-fruited ‘Lady Blake-ford’ display a tighter, more columnarform than typical plants and are suited forsmall spaces. For pollination services, ‘Jer-sey Knight’, ‘David’, and ‘Baltimore Buzz’are good males, especially for the mid-At-lantic and Northeast.
Ilex opaca is not a tree for impatientgardeners. Although it grows faster in sunthan shade, it may take 20 years or moreto attain its most attractive form. Somegardeners report faster growth with inten-sive fertilization. Providing sufficientwater in the heat of summer also tends tospur the growth rate.
“Ten to 12 inches of growth per year isa reasonable expectation in the mid-At-lantic,” Kuhl says, “perhaps somewhatfaster for the cultivar ‘Glen Ellen’. It maybe that the forms with larger leaves grow alittle faster than those with smaller leaves,but I know of no research that confirmsthis.” As it turns out, Kuhl’s hunch may bespot on. The faster-growing cultivars forUSDA Zone 8 and northward include‘Angelica’, ‘Carnival’, and ‘Clarissa’, all ofwhich are female plants with at least mod-erately large leaves.
The scrub holly (I. opaca var. arenicola,Zones 8–9, 11–9) is a smaller, often shrub-bier variety of American holly that is espe-cially suited for xeric sites. The smallerleaves—usually less than three incheslong—and strongly rolled leaf margins areparticularly attractive. Scrub holly growsnaturally only on sandy inland dunes ofthe central Florida peninsula but has beenplanted successfully as far north as theFlorida panhandle and may have evenwider uses in xeric gardening. Unfortu-nately, its availability is currently limited.
TOPEL HOLLYThe original topel holly (Ilex ✕attenuata,Zones 6–9, 9–4) arose as a natural hy-brid whose parentage likely includes theAmerican and dahoon hollies (I. cassine),although the myrtleleaf holly (I. myrtifo-lia) is also a suspected parent. The selec-tions ‘Savannah’ and ‘East Palatka’ are
good fast-growing substitutes for Amer-ican holly, particularly in USDA Zones 8and 9. Both are similar to American hollyin form and foliage.
‘East Palatka’ was selected by leg-endary holly expert H. Harold Hume inthe 1920s from a tree growing near EastPalatka, Florida. It produces abundantfruit on plants that grow 30 to 45 feet talland 15 feet wide. With their dark greenfoliage and symmetrical crowns, theymake excellent specimen trees. Unifor-mity in shape and size coupled with apositive response to pruning make ‘EastPalatka’ useful where consistency is im-portant. Huge ‘East Palataka’ hollies arescattered throughout the campus ofFlorida State University in Tallahassee,
where they have maintained their beau-ty despite being trampled by foot trafficand crowded by parking lots for years.
‘Savannah’ (Zones 7–9, 9–4) wasfound in the 1960s in Savannah, Georgia.It more closely resembles I. opaca in leafform than does ‘East Palatka’, but its fo-liage is often a lighter, yellowish green.‘Savannah’ features a dense, symmetricalcrown and abundant bright red fruitsthat give winter trees a reddish cast evenfrom a distance. It grows faster thanAmerican holly and can become 45 feettall with a six- to 10-foot spread.
The Foster hybrids (sometimes listed asIlex ✕attenuata ‘Fosteri’, 6–9, 9–4) startedas chance seedlings of crosses of the da-hoon and American hollies, in Bessemer,
An attractive screening and hedge plant, ‘Foster #2’ is a cultivar of topel holly.
Alabama, in the 1940s. ‘Foster #2’, proba-bly the best female selection, is a denseconical tree with glossy, dark green leavesthat are often longer than wide and bearconspicuous marginal teeth. This is one ofthe few Ilex ✕attenuata selections that per-forms well north of the southeasterncoastal plains. Typical trees are 15 to 25 feettall, about 12 feet wide, upright and pyra-midal. It is excellent as a screening hedgeon large properties.
Three yellow-fruited selections of Ilex✕attenuata are particularly attractive.‘Alagold’ originated as a seedling of ‘Foster#2’, to which it is very similar in form and
foliage. The bright-yellow-fruited ‘Bi-enville Gold’, with its narrow form anddark green leaves, was introduced in 1995by Tom Dodd, owner of Dodd & DoddNative Plant Nursery in Semmes, Alaba-ma, and is suitable for warmer climates.‘Longwood Gold’, introduced in the late1980s by Longwood Gardens in KennettSquare, Pennsylvania, is reportedly morecold hardy than typical red-fruited hybrids.
Even with its coastal plains origin, Ilex✕attenuata can be used well north of itssouthern provenance. “We’ve had somehighly favorable experiences with clonesof Ilex ✕attenuata,” says Richard Larson,propagator for the Dawes Arboretum incentral Ohio. “‘Sunny Foster’ holly fromthe U.S. National Arboretum has done
super here with only slight damage fromthe severe cold we had last winter.”
YAUPONYaupon (Ilex vomitoria, Zones 7–10, 12–7)is the native holly most often grown in thesoutheastern United States. This is pri-marily a plant of the coastal plains fromsoutheastern Virginia to Florida and westto Texas, but it has a much wider range incultivation. Its many forms, selections, andcultivars are favorites of home gardeners,growers, and commercial landscapers.
The leaves are small and mediumgreen with bluntly toothed margins.
Those of cultivated plants are usually lessthan an inch-and-a-half long and notmore than about a half-inch wide, withthe leaves of shade-grown plants beinglarger and darker green than plants grow-ing in full sun. Female plants typicallyproduce abundant, conspicuous brightred drupes in winter.
For gardeners who enjoy plants withcultural connections, yaupon is unsur-passed. It is touted by ethnobotanists asthe plant from which certain NativeAmerican tribes brewed a ceremonialblack drink, a caffeine-rich concoctionthat also served as a purgative when con-sumed in quantity—hence the specificepithet. A similar beverage was also usedby American colonists as a tea substitute.
Yaupon’s popularity as a landscapeshrub stems more from garden-worthinessthan from its historic significance as a folkremedy. It is tough, adaptable, drought andsalt tolerant, requires little maintenance,and with its numerous forms, it fulfillsmany landscape needs. Dwarf, densely fo-J
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Yaupon holly selections come in a range of shapes and sizes, including the compact ‘Nana’.
SourcesArborvillage, Holt, MO. www.arborvillagellc.com.
Fairweather Gardens, Greenwich, NJ.www.fairweathergardens.com.
Forest Farm, Williams, OR.www.forestfarm.com.
Mail Order Natives, Lee, FL.www.mailordernatives.com.
McLean Nurseries, Parkville, MD.(410) 882-6714.
RareFind Nursery, Jackson, NJ.www.rarefindnursery.com.
TNZ Nursery, Louisville, KY.www.tnz.us.
Woodlanders, Aiken, SC. www.woodlanders.net.
Resources Florida’s Best Native Landscape Plantsby Gil Nelson. University Press ofFlorida, Gainesville, Florida, 2003.
Hollies: A Gardener’s Guide by BrooklynBotanic Garden and the Holly Societyof America. Brooklyn Botanic Garden,Brooklyn, New York, 1993.
Hollies for Gardeners by ChristopherBailes. Timber Press, Portland, Oregon, 2006.
Hollies: The Genus Ilex by Fred C.Galle. Timber Press, Portland, Oregon, 1997.
Holly Society of America,www.hollysocam.org.
liaged compact forms such as ‘Schillings’,‘Nana’, and Bordeaux™ make excellent lowhedges or borders and can be pruned toany size up to about three feet tall.
Most of the dwarf forms are similar toone another and can be mixed in a singlehedge that includes both male and femaleplants. Bordeaux™ is a sport of ‘Schillings’that features burgundy-colored winter fo-liage. Larger upright forms include ‘Gray’sGreenleaf ’, ‘Lynn Lowery’, ‘Fencerow’,‘Will Fleming’, and the yellow-fruited‘Yawkey’, all of which can grow 20 feet tall.
The weeping forms of yaupon are ar-guably the most attractive of this species;cultivars such as ‘Pendula’ and ‘Folsom’sWeeping’ are widely available and are per-fect for accenting corners or tall facades.Both are narrow and upright, grow toabout 20 feet tall, and have strongly droop-ing branches that should be allowed tohang gracefully and never be pruned, ex-cept to keep the branch tips off the ground.
DAHOONThe dahoon holly (Ilex cassine, Zones7–10, 12–7) is naturally distributed alongthe coast from southeastern North Caroli-na to Louisiana, including all of Florida. Itis primarily a wetland tree, but it adaptswell to the garden, even in relatively drysites. Dahoon is faster growing than Amer-ican holly and will produce fruit in partshade or full sun. The one- to four-inchleaves are much longer than wide, mediumgreen, somewhat glossy, and typically lackspiny lobes. Dahoon produces flowers andfruit at an early age, responds well to prun-ing, and bears numerous bright red drupesin winter. Mature plants in the wild cangrow 35 feet tall, but garden plants rarelyexceed 20 feet.
The best dahoon cultivars include ‘Per-dido’ and ‘Tensaw’, introduced by TomDodd. ‘Perdido’ is a small, adaptable treeor large shrub with a mostly roundedcrown and a profusion of red winter fruit.‘Tensaw’ is slightly smaller, but is also a sin-gle-trunked tree or medium-sized shrub.Its densely borne leaves are shorter androunder than other dahoon selections. Yel-low-fruited forms are sometimes market-ed as I. cassine forma aureo-bractea.
Ray Head, president of the Holly Soci-ety of America, grows ‘Tensaw’ and ‘Per-dido’ in his North Carolina garden andcounts them among his favorite evergreen G
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Top: The ‘Perdido’ selection of dahoon holly shows off pearly pink and red fruits. Above:The aptly named inkberry is widely adaptable in American gardens.
hollies. “These may be coastal plain plantsbut they do very well for me here in thePiedmont where winter temperatures candrop to zero,” says Head. “My plants pro-duce loads of winter fruit to feed robinsand waxwings. The fruit of ‘Tensaw’ is anorange color, which adds to its interest.”
MYRTLELEAF HOLLYThe closely related myrtleleaf holly (I. myr-tifolia, Zones 7–10, 12–7) is considered bysome authorities to be a variety of dahoonbut is probably better treated as a distinctspecies. It has the smallest leaves of any ofour native evergreen hollies, averaging lessthan an inch long and only about a quar-ter-inch wide, similar in length to those ofyaupon, but much narrower. The marginsare usually smooth, rarely with a few tinysharp teeth. Myrtleleaf holly grows toabout 15 feet in cultivation, with an opencrown. Yellow-fruited forms of this speciesare particularly stunning.
BLACK-FRUITED HOLLIESAmong the native black-fruited hollies,inkberry (Ilex glabra, Zones 4–10, 10–4) isthe most popular and widely available. It isprimarily a wetland plant in nature, broad-ly distributed in low pinelands and alongswamp margins from Nova Scotia south toTexas. But it adapts well to garden soils, aslong as they are at least moderately acidic.Mature plants can potentially grow toeight feet tall, but are usually much small-er. They can be pruned to a more compactform, lending themselves to use in foun-dation plantings or along walkways. Themain stem of inkberry grows somewhatslowly, but plants can spread fairly rapidlyby vigorous, quick-growing undergroundrunners. Mature plants of some selectionscan create a dense hedge if pruned.
There are at least two dozen inkberrycultivars, distinguished mostly on the basisof form, foliage, and fruit color. Compactforms are most popular, the best of whichinclude ‘Compacta’, ‘Densa’, and ‘Nigra’.Unlike other selections, ‘Nigra’ does notlose its lower leaves with age—a typicalproblem for standard inkberries.
‘Leucocarpa’ (sometimes referred to asI. glabra forma leucocarpa) is a white-fruit-ed form that has been available in nurseriessince at least the 1950s. ‘Ivory Queen’ and‘Alba’, both of which are probably selec-tions of ‘Leucocarpa’, also bear white fruit.
Like many natives, inkberry does wellin the garden beyond its natural range.Eric Garris, curator of the holly collectionat the Bernheim Arboretum and ResearchForest in north-central Kentucky, growsseveral cultivars. “Ilex glabra is not nativeto Kentucky but performs well here,” saysGarris. “We currently have nine cultivarsin our collection. I like ‘Compacta’ for itshardiness and rounded form and ‘IvoryQueen’ for its great, glossy foliage andwhite berries. ‘Winter Wine’ is also a fa-vorite because it is very hardy and has aburgundy tint during winter.”
HOLLIES IN THE GARDENWhether you’re seeking winter interest,four-season appeal, or sources of food forwildlife in your garden, you can’t gowrong with native evergreen hollies.“They can add wonderful year-roundtexture and depth to any landscape,” sayslandscape architect Lisa Delplace ofOehme, van Sweden and Associates in
Washington, D.C. “This is particularlytrue when used in the mid-ground of aplanting bed where the leaf shape, gloss,and berries are visible.”
Several make stunning specimens, ei-ther with a single or multiple trunks. Someselections perform as elegant street trees.Others can be massed as a screen, plantedas an informal hedge, or pruned for a moreformal landscape. “Hollies are a wonderfulcounterpoint to the seasonal variations ofperennials and grasses,” says Delplace.
While other components of the gardenwax and wane throughout the year, ever-green hollies contribute elegant stability.Few native species equal them for en-livening the winter landscape. �
Gil Nelson is an author, photographer, andbotanist based in Georgia. His next book,The Best Native Plants for Southern Gar-dens: A Handbook for Gardeners, Home-owners, and Professionals, is scheduled forrelease by University Press of Florida in 2010.K
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‘Will Fleming’, an upright yaupon holly selection, forms an allée in this Austin, Texas, garden.
