What is a Conifer Tree?

• Conifers are, most simply, plants that have cones. So yes, pine trees are conifers; we all know about pine cones!

• Are all conifers pine trees? No, there are spruce and fir and cypress and redwoods and dozens more. However, the pine family is the largest family within conifers, and both spruces and firs are members of the pine family (Pinaceae) so for most of us, many of the conifers with which we are most familiar, are pines!

• Are all conifers trees? We all know that classic, Christmas tree shape, and unfortunately conifers get tagged as boring because there is an idea that all conifers look like that. Did you know that conifers naturally occur in 10 completely different shapes, from tall and upright to weeping to flat and spreading? Conifer shapes

• All conifers are not evergreen! Ever heard of a bald cypress, the denizens of the Southern bayous? They got the nickname ‘bald’ because they lose their needles in the winter. So do larch and dawn redwood, but they are still conifers, because they bear cones.

• Not only are all conifers not evergreen, they are not all green! Colorado blue spruce is vividly blue, many other conifers are vibrant yellow or gold, and you can find colors ranging from silver and white through yellows and blues to purple, brown and reddish at different times of the year. Oh, and of course, green!

• So ok, we get it now, conifers are complicated, but they all have cones and we know that they all have needles instead of leaves, right? Well…sorry to make it even MORE complicated, but there are a few conifers that don’t have needles, they have leaves! Native to Australia, they don’t look anything like our idea of conifers. So what makes them conifers then? Remember the first bullet point: they bear cones!

Conifers of Southern United States

By Web Editor
December 6, 2019

Discover the rich diversity of conifers in South Carolina.

The conifer, Pinus palustris (longleaf pine)

When one conjures up images of the deep South, they typically think of azaleas, magnolias, live oaks, and yes, that noxious vine from China, kudzu. Aside from the ubiquitous pines, scant attention is afforded conifers. After all, when one thinks of conifers, the vast forests of spruce and fir that dominate boreal regions often come to mind.

Although conifers are found in a variety of climates throughout the world, people with a passion for growing conifers and widespread landscape use of conifers is still largely a northern and Pacific Northwest phenomenon. In what is now the southern United States, an immense coniferous forest dominated by longleaf pine (Pinus palustris) once covered more than 90 million acres from Virginia to Texas. This and several other southern pines are still mainstays of the forest products industry.

The conifer, Araucaria angustifolia (Paraná pine)

Native Pines in the South's Best Small Town

I live and garden in Aiken, South Carolina, which sits squarely in this pine forest region. Today, the 11 pine species native to the southern United States are all represented in Aiken. Other native conifers including Taxodium, Juniperus, and Chamaecyparis are also found here. Soils, climate, and cultural history combine in Aiken to provide a rich horticultural history. Today, there are few communities that can match Aiken’s diversity of trees and other plants.

The International Oak Society has credited Aiken with having the most comprehensive collection of oaks in the United States, but Aiken likewise has a wealth of cultivated conifers. Many genera and species not hardy in colder regions, and/or generally uncommon in cultivation, are represented. Last year, when past ACS president Tom Cox visited me, I could sense that he was surprised at the species diversity found within such a concentrated area.

The conifer, Afrocarpus falcatus (Outeniqua yellow-wood)

Conifers at the Hitchcock Woods Preserve

The city of Aiken was laid out in the 1830s by the railroad being built to provide a link from Hamburg (across the Savannah River from Augusta, Georgia) to Charleston, South Carolina. At the time of completion, the railroad was the longest in the world. In the antebellum period, Aiken was a popular summer retreat for coastal planters. In the late 19th century, it became a popular health resort and, later, a winter home for wealthy northerners who pursued hunting and equestrian sports.

It now is a small, vibrant city, retaining an equestrian focus and attracting a growing population of retirees. Today in Aiken’s 2,000-acre Hitchcock Woods Preserve, one can see ancient longleaf pines and other native conifers, including disjunct occurrences of Juniperus communis and Pinus virginiana. In the beautiful Hopelands Gardens, enormous deodar cedars (Cedrus deodara), pines, and rare conifers such as Fokienia hodginsii and Cupressus funebris can be seen. Throughout Aiken’s historic district, broad tree-filled parkways display a remarkably varied tree collection that includes many noteworthy conifers. Quite a few private estates and home landscapes have notable conifers.

The conifer, Wollemia nobilis (Wollemi pine)

Woodlanders in the South

One private estate has an especially varied collection with many rare species from around the world; included are many Southern Hemisphere rarities such as Araucaria angustifolia, A. araucana, Afrocarpus falcatus, Podocarpus parlatorei, and Wollemia nobilis. Everything within a 4-mile radius of downtown Aiken is included within the Aiken Citywide Arboretum project area.

Efforts to locate, identify, and GPS a typical, outstanding, or sole example of every tree species within the project area is underway. The conifers have been largely completed, enabling one to pinpoint an example of many species. While various horticultural varieties of conifers are included, there has not been any special effort to pursue the endless variety of named selections and mutant forms popular with conifer collectors.

Aiken’s collection, therefore, is species focused. We are proud of our tree program and pleased to have this opportunity to introduce a diverse collection of conifers growing in a region of the United States where most visitors may not expect to find them.

Text by Bob McCartney.

Bob McCartney and George Mitchell operate Woodlanders, Inc., an internationally known source for more than 1,000 kinds of rare and hard-to-find plants, located in Aiken, South Carolina.

Intermediate Conifers: Creating Variety in your Garden

By Web Editor
December 7, 2019

Looking to spice up your landscape? Find out more about “the forgotten conifers.”

In the two most recent installments of Conifer Corner, I’ve been discussing outstanding conifers in each of the four size categories recognized by the American Conifer Society (ACS), beginning with the smallest size category (Miniature conifers) and working up to larger conifers. In this edition of Conifer Corner, I continue this discussion by considering Intermediate conifers.

The ACS defines intermediate conifers as those that grow 6-12” per year and reach a height of 6’ to 15’ at age 10. They are not adorable little miniatures or dwarfs that can fit into a container or rock garden. Conversely, intermediates won’t dominate a landscapeas a specimen, like a large conifer. Nevertheless, intermediate conifers are an important group of trees because they fulfill an important function in landscape design and development.

Unlike their smaller cousins, miniature and dwarf conifers, intermediate conifers are less likely to get “lost in the shuffle” in a busy landscape design. Unlike large conifers, intermediates are less likely to interfere with power lines or other overhead obstruction and are better suited to planting closer to houses and allow greater flexibility in site selection.

As with all of the trees that I’ve discussed in this series on conifers in the ACS size classes, there is considerable variation in growth depending on site and cultural practices. This is especially true with intermediates. Some intermediate conifers growing on a good site could reach a size comparable to large conifers.

There is no single “official” trial garden where conifer sizes are determined. Size classes are based on observations by growers and conifer enthusiasts and a given cultivar may be listed as an intermediate in one reference and as a large in another. In general, size classes referred to in Conifer Corner articles are based on the ACS Conifer Database.

Intermediate Conifers for the Central Region

Pinus cembra ‘Silver Sheen’ Swiss stone pines
are reliable conifers in Michigan landscapes

Pinus cembra (Swiss stone pine)

Conifer expert Chub Harper has a passion for plants that is matched by few and few plants get him as excited as Pinus cembra. Just mention Pinus cembra and Chub goes all Will Rogers. “I’ve never met a cembra I didn’t like," Chub enthuses. “This is one of those plants I just don’t understand why we don’t use more.” Indeed, it’s easy to understand Chub’s swooning for Swiss stone pine. This species maintains a tight compact form with a straight single leader, giving it a stately elegance without pruning.

Moreover, Pinus cembra has beautiful blue green needles that often take a silvery sheen. Cembra is fairly tolerant of a range of sites and is variously listed as zone 3 or 4, so it is hardy in most of the Lower Peninsula. Pinus cembra is one of those plants that even the straight species is distinctive enough tomake an impression. In addition, there are a number of cultivars on the market. Note that some of the cultivars included here fit into the Dwarf size class.

.

• Pinus cembra ‘SilverSheen’
  A striking cultivar of P. cembra with silvery blue needles. Zone 5.

• Pinus cembra ‘Chalet’
  A pyramidal to upright form of Pinus cembra. There is a terrific specimen in the Harper Collection. Zone 4, though also reported to Zone 3.

• Pinus parviflora (Japanese white pine)
  A solid performer in Michigan. There are a variety of cultivars of Japanese white pine, some of which I’ve mentioned in earlier Conifer Corners.

• Pinus parviflora ‘Bergman’
  This is one of the more striking forms of Japanese white pine, with twisting bluegreen needles. Variously listed as a dwarf or an intermediate.

• Pinus parviflora ‘Fukuzumi’
  The formon this plant can be variable, but its recurved blue-green twisted needles give it consistent appeal.

The color and texture of the conifer, Chamaecyparis pisifera ‘Filifera Aurea’ make it a show-stopper.
Golden thread falsecypress (Chamaecyparis pisifera 'Filifera Aurea’)
welcome visitors to the Harper Conifer Collection at Hidden Lake Gardens. Photograph by Jack Wikle

Chamaecyparis pisifera ‘Filifera Aurea’ (Golden thread false cypress)

Yes, the Latin name is a mouthful, but this plant is a show-stopper like few others. ‘Filifera Aurea’ generate interest from a distance due to their bright yellow color and upright weeping form, as well as up close due to their impossibly long threadlike foliage.

Abies concolor ‘Conica’ is a striking upright form of
concolor conifer that is well adapted in Michigan

Abies concolor ‘Conica’

Continues the theme of color – this time striking blue. Abies concolor ‘Conica’ also continues the theme of underused conifers. This tree’s stately upright form makes it a prime choice as a specimen plant. Put one of these in your yard and you’re guaranteed to have all of the neighbors asking “Whatzzat?”

Picea glauca ‘Pendula’

Technically this is listed as an intermediate, but on better sites it may push toward the large category. Also, this cultivar has been around long enough that it’s possible to find some decades-old larger specimens. The tight form and drooping branches make it easy to envision this plant in a snow-blanketed mountainside.

Abies koreana ‘Silberlocke’

Gets double marks for showmanship. The needles on this cultivar of Abies koreana are highly recurved, that is, they are turned upward to reveal their silvery underside. While that alone is enough to give the tree tremendous ornamental appeal, ‘Silberlocke’, like most Korean firs, also produces prodigious amounts of colorful cones. Although cones on firs make Christmas tree growers cringe, in this case it adds to the plant’s landscape appeal.

Need a break from“blue spruce burnout”? Abies lasiocarpa ‘Arizonica Compacta’
has outstanding conifer form and color

Abies lasiocarpa var. arizonica (Corkbark fir)

An argument for the lumpers and splitters. Some references list this as a variety or even sub species of Subalpine fir (A. lasiocarpa) while others (for example, the Gymnosperm database) list corkbark fir as its own species (A. bifolia). In the nursery trade, var. arizonica holds sway. Another high elevation conifer from the mountain southwest, corkbark fir is a striking tree that can often match Picea pungens for blue color.

Larix kaempferi provides a dramatic contrast in conifer form and color

Larix kaempferi ‘Pendula’

Deciduous conifers always make a unique contribution to the landscape and this weeping larch is no exception. This plant commands interest anytime during the growing season, but especially in the early spring when the new bright green needles are just beginning to flush. According to the ACS, this tree is widely mislabeled as Larix decidua ‘Pendula’.

 The yellow highlights of the conifer, Picea pungens ‘Walnut Glen’
can brighten up even a dreary fall day in Michigan

Picea pungens ‘Walnut Glen’ (Walnut Glen Colorado blue spruce)

Is an interesting twist on the old standby, Colorado blue spruce. This P. pungens cultivar has a golden cast to its needles, which often make it look like the sun is shining on it even when it’s in the shade. Reportedly adapted to a fairly wide range of site conditions though the variegated yellow needles may suffer scorch under stress.

Pinus aristata (Bristlecone pine)

We can’t really recommend bristlecone pine as an outstanding grower in Michigan, but it’s a fascinating tree and it will grow on suitable sites here in Michigan. In their native habitat, bristlecone pines are among the oldest living things on earth. The Rocky mountain form (P. aristata) can live to nearly 3,000 years old and specimens of the Great Basin form (P. longaeva) have been found that are over 4,800 years old. Although we don’t expect a Bristlecone pine to live thousands of years in Michigan (and, in any case, we won’t be around to see it), this makes an interesting specimen in the right spot. Look for a site with good drainage and relatively good air flow. Like many trees adapted to the arid west, these pines don’t like wet feet or high humidity.

Columnar conifers such as Thuja occidentalis ‘Degroot’s Spire’ are especially
dramatic when grouped for effect

Thuja occidentalis ‘Degroot’s Spire’

In general, arborvitae are the kinds of plants that don’t usually get people too excited. However, this upright columnar form makes a great accent and can add a formal appearance as a border or can be grouped for effect.

Thuja occidentalis ‘Hetz Wintergreen’

Another upright form of arborvitae. ‘Hetz Wintergreen’ is noteworthy for a couple of reasons. It tends to maintain its green color throughout the winter when many other conifers turn off-color and it tends to maintain a strong central leader, whereas many columnar arbs can develop multiple leaders or bend over under snow loads. Excellent for a year-round screening hedge and windbreak.

Picea omorika ‘Pendula Bruns’ (Weeping Serbian spruce)

It’s always hard to go wrong with a Serbian spruce. ‘Pendula Bruns’ is a little slower growing and has a little tighter form than ‘Pendula’and ‘Berliners Weeper’ – more on those two in the next Conifer Corner.

Picea glauca 'Densata’ (Blackhills spruce)

Depending on the reference, Black hills spruce is listed as either a true botanical variety (var. densata) or simply as a cultivar. Regardless of the taxonomy, this is a versatile tree that we’ll likely see more of in the future. As the Latin name ‘Densata’ implies, Black hills spruce has a tight, dense growth habit and maintains a nice pyramidal form. Its growth rate is slower than the straight species or blue spruce so it’s less likely to get out of hand and provides more flexibility in site selection. With its uniform compact growth, Black hills spruce also shows promise as a table top Christmas tree.

Text and photographs by Dr. Bert Cregg. Additional photograph by Jack Wikle.

Dr. Bert Cregg is an Associate Professor in the Departments of Horticulture and Forestry at MSU.

Evergreens and Companion Planting

By Dave Resavage
February 22, 2020

Find companion plants for your evergreen conifer garden to add a splash of color and texture!

A companion plant, Bigleaf Hydrangea (Hydrangea macrophylla ‘David Ramsey’)
Photo:Eaton Farms / Pennsylvania Pride Trees

Conifers, most of which are evergreens, naturally make great neighbors to ornamental companion plants in the garden. Many novice gardens and homeowners embarking on a new garden design or landscape renovation are unaware of the magic conifers will bring to their schemes when combined with their favorite ornamental flowering shrubs, trees, perennials, grasses, and even tropical plants, such as bananas! The horticultural marriage between evergreen conifers and companion plants can ensure years of gardening bliss when thoughtfully arranged.

Combining Conifers and Companion Plants

The vast array of conifers and companion plants offered in the market today make it possible for harmonious, interesting, and dramatic garden designs. Particular attention must be paid to size, scale, and growth rate of companion plants. If ignored, unwanted consequences and disappointment may ensue.

It would be foolish to invest time and money into a rare and unusual conifer and to plant it directly next to your favorite shrub or tree companion, only to see it become quickly outgrown by its companion, causing irregular growth for both plants!

Scale and maturation of companion plants is essential to achieving a visually pleasing garden of mixed arrangement. Beginning gardeners in the planning stage should allow ample room for growth between their conifer specimens and companion plants. Some plants, especially woody ornamentals and perennials, are notorious for growing larger than the printed information tag accompanying them.

The companion plant, the Blue Holly (Ilex x meserveae ‘Honey Maid’)
Photo: Eaton Farms / Pennsylvania Pride Trees

I have found myself in this difficult situation; faced with the task of removing the old in order to make room for the new and exciting, then finally arriving at a happy conclusion that most times the removal was for the best, as a garden landscape is ever changing.

Many new plants offered today, both conifers and companion plants, are far superior to the cultivars of yesteryear and new additions to the garden can be a welcome breath of fresh air, especially in a mature garden. Broadleaved evergreens, such as rhododendron, also make good companion plants for conifers.

Conifers and Woody Ornamentals Combinations

Since evergreen conifers afford texture and year-round color, woody ornamentals, like trees and shrubs are natural companion plants with their seasonal changes in appearance. Always bear in mind their ultimate size and mature visual appearance next to their conifer neighbors.

It only takes one visit to a well-stocked nursery to realize that your only limit when choosing companion plants is your imagination. (I don’t like to say budget is a limit when choosing garden plants because plants, unlike most other purchases, will GROW! You can always buy smaller plants, just be patient and offersome extra TLC with young plants.)

While at your favorite nursery, look for what is currently in bloom, but also be attentive to how the plant will look later in the season, after the flowering period is complete. Many woody ornamentals add great winter interest to the garden with colorful stems, heavily textured bark and unique branching structure.

A conifer complement, the Golden Hinoke Cypress (Chamaecyparis obtusa ‘Crippsii’)
Photo: Eaton Farms / Pennsylvania Pride Trees

Additionally, old garden favorites are now offered in variegated and all golden foliage forms, such as the hardy blue holly (Ilex x meserveae ‘Honey Maid’)! This spectacular new variegated evergreen holly, offering a dark green leaf outlined with a rich golden margin, is very hardy. It makes an outstanding complement to bluish colored conifers, especially during the winter months.

The lush, blue, purple and lavender colored flowers of Hydrangea macrophylla ‘Endless Summer’ or Hydrangea macrophylla ‘David Ramsey’ when combined with a golden conifer, such as Chamaecyparis obtusa ‘Crippsii’ or Taxus cuspidata ‘Dwarf Bright Gold’ can transform the sunny summer garden into a visual explosion of color!

Best of all these two new big leaf hydrangea cultivars are repeat bloomers, June through October, and will reliably produce flowers every year, even after a harsh northeastern winter. They produce flowers on both old growth and new woody stems, thus ensuring outstanding flower display.

Equally, the shady summer garden can be brightened up with the unusual pairing of the shrubby form, leathery-leafed, evergreen Aucuba japonica ‘Variegata,' combined with such mounding/prostrate conifers, as Taxus baccata ‘Repandens’ or Cephalotaxus harringtonia ‘Duke Gardens.'

Those gardeners with restricted space who desire a small spring flowering tree, would benefit from the association of the pink flowering Cercis canadensis ‘Forest Pansy’ with Picea pungens ‘Procumbens’. The new, bluegreen flush of growth on the picea, combined with the rich crimson leaf color of the cercis, make for an unforgettable spring show, guaranteed to only improve with each passing season!

With so many trees and shrubs available, the association between conifers and woody companion plants is endless. Woody ornamentals will provide seasonal colors and textures, but rely upon the conifers to continue the show year round. Be creative, look for interesting attributes that will give woody companion plants year round appeal with your conifer gems!

A companion plant, the 'Forest Pansy' Redbud (Cercis canadensis ‘Forest Pansy’) Photo: Eaton Farms / Pennsylvania Pride Trees

Perennials, Grasses, and Tropical Plants with Conifers

A garden consisting of only woody ornamentals and conifers would be pretty but sometimes not visually interesting. When associating perennials, grasses and YES, even tropical plants with conifers and woody ornamentals, a garden is yet again transformed, taking on an added dimension of depth, scale, and drama.

With limited space in this article, I can only offer some interesting suggestions utilizing these associations in the garden. But again, the same rules apply. Always be mindful of mature plant size and scale.

Perennials and grasses are best used in mass plantings if space permits. They should be at the very least displayed in groupings; odd-number groups seem to work best. A garden design consisting of too many different single selections looks busy and visual clutter in the garden should be avoided.

A great contrast plant in the garden, especially when used in groups or mass plantings, is Heuchera, commonly known as coralbells. This plant has seen an explosion of cultivars in endless colors recently. Heucheras work well planted in mass groupings and used as a boarder edging in the semi-shaded garden.

The companion plant, Eastern redbud (Cercis canadensis ‘Flow’)
Photo: Eaton Farms / Pennsylvania Pride Trees

Heuchera ‘Caramel’ offers a rich, bronze orange color, guaranteed to get noticed in the garden. Plants from the genus Hemerocallis, commonly known as daylilies, might be considered an old standby but are now being offered in endless color combinations.

Many new varieties exist with extended bloom periods and repeat bloom cycles; these new cultivars are not your grandmother’s daylilies! Some new cultivars can be a bit pricey but are well-worth the investment for their unusual colors and high performance. Additionally, most are tough, enduring garden perennials, which do well in full-sun or semi-shade.

A favorite grass-like perennial of mine that works well in both sun and shade is Liriope muscari ‘Variegata.' This plant has endless uses, from being planted en masse as a groundcover to utilization as a wispy edging/border plant. It combines well with conifers and perennials alike, growing only about 12 inches to 15 inches in height. The colorful variegated leaves endure well into early winter, making it a hardworking plant, worthy of garden space.

A true dwarf grass with vibrant golden color, making a splash in the shady and semi-shaded garden is Hakonechloa ‘Aureola’. This garden grass combines perfectly with hostas and ferns in the shady/semi-shaded garden and is tolerant of dry soils. A graceful grass with arching bright yellow blades, it looks great when paired with a conifer such as Cupressus nootkatensis ‘Pendula.'

A few years back I started toying with the idea of adding tropical plants to my northeastern Pennsylvania garden, and after some research, I discovered that my idea was well within the grasp of my garden design, even though I commonly experience winter lows typically around zero degrees Fahrenheit.

A true hardy tropical perennial is the Musa basjoo, commonly referred to in the garden world as Japanese fiber banana. This exotic banana will grow easily to 10-feet tall or more in a single season. Large dramatic light green leaves up to 6-feet long are sure to make a few heads turn. The large leaves combine well with other intermediate and large conifers, such as Cedrus atlantica ‘Fastigiata,' as I have done in my own garden.

The Nootka cypress (Cupressus nootkatensis ‘Pendula') with Hakone Grass (Hakonechloa 'Aureola')
Photo: David Resavage, from a landscape renovation he designed

Minimal winter protection in the fall ensures this large growing tropical will return year after year. Simply cut the banana stalks down to about 6 inches tall after the first frost. Cover the stalk completely with deep hardwood mulch or use leaves. I construct a simple cage around the stalks and surrounding root zone before filling with leaves at least 15 inches to 18 inches in depth.

In early May, I remove the mulch/leaves and witness the banana returning from the dead! Try this and by late June your banana will be taller than you and well on its way to giant proportions creating major garden drama! Be creative in your garden design and plant associations as the plant selections offered today are endless. Be on the lookout for new and up-and-coming plants, which are always being marketed.

Try new selections and don’t be afraid to make changes to your garden. A garden design is never truly complete because in order for a garden to stay fresh and alive, changes inevitably have to be made.

The Japanese fiber banana (Musa basjoo) with
Fastigiate Atlas Cedar (Cedrus atlantica ‘Fastigiata’) and
Variegated Lily Turf (Liriope muscari ‘Variegata’)
as an edging plant at the Resavage garden in Wilkes Barre, Pennsylvania (zone 6a)

David Resavage is a professional landscape designer possessing an abounding love of conifers, tropicals, and any plant deemed rare or unusual. After pursuing an academic career in landscape design and ornamental horticulture, he began actively pursuing, studying and utilizing the most unusual, rare and dramatic landscape plants in his designs.

He has traveled extensively throughout the British Isles, Canada and the Caribbean researching and observing native and ornamental plantsin relation to garden design. He divides his time between his home-based ornamental specimen garden in Wilkes-Barre, and a more natural woodland garden at his summer home on Sylvan Lake, about an hour outside Wilkes-Barre.

His gardens have been repeatedly featured in local periodicals for their unusual and noteworthy design style and provocative use of plant materials. He is the chief landscape designer for Hanover Nursery in Wilkes-Barre, Pennsylvania.

Conifer Cousins: Ginkgo biloba

By Sara Malone
November 30, 2019

Take a deep dive into a biological cousin of the conifers: the Maidenhair Tree.

Ginkgo are not strictly conifers, but the American Conifer Society includes them
under its umbrella

My introduction to Ginkgo biloba was years ago, as a third year biology student at Vassar College in Poughkeepsie, New York, when my path between fall semester classes took me past a large tree with foul-smelling fruit. I was puzzled, because I had passed the tree for two years and never so much as wrinkled my nose. A member of the botany faculty enlightened me. It was a Ginkgo.

Ginkgo are dioecious and wind-pollinated; the tree in question was female, and the only male specimen on campus was far enough away that the wind conditions had to be just right at pollination time, which made success sporadic. Little did I know that that was the last time that I would ask a question about a Ginkgo and receive an unequivocal, short, factual, useful answer!

I embarked on the quest to make order of the world of dwarf Ginkgo cultivars only to learn that it is a world rife with confusion, lack of documentation, little long-term growing experience and enormous reliance on second-or even third-hand observations and interpretations. The usual frenzy on the part of collectors to obtain the latest, rarest, most unusual cultivars has added to the obfuscation, as it provides motivation to keep nomenclature fuzzy and the number of different offerings high. These conditions plague other genera, as collectors of dwarf conifers are only too well aware, but the world of dwarf Ginkgo has some peculiar characteristics which exacerbate the situation.

The History of Ginkgo

Ginkgo are not strictly conifers, and, at this writing, have been classified into their own division, Ginkgophyta, with a single class, order, family, genus and species, of which Ginkgo biloba is the only extant representative. The Ginkgo fossil record dates back some 200 million years. Native to China, they are believed to be extinct in the wild, as today’s populations now appear to have been cultivated. Ginkgo are, however, gymnosperms, and so are more logically lumped with conifers than not, and the American Conifer Society includes them under its umbrella. Ginkgo biloba ‘Mariken’ was even chosen as the American Conifer Society's Collectors Conifer of the Year in 2007.

Even those who have not grown Ginkgo almost certainly recognize them, as they are used ubiquitously as street trees, due to their extensive range, high tolerance of air pollution and their resiliency to wind and snow. In addition, because they are stoic, long-lived, and generally slow growing, they require little maintenance. Their durability is exemplified by the six Ginkgo trees which survived the atomic bomb blast in Hiroshima, a trauma not likely to be approximated in anyone’s garden, black thumbs notwithstanding! The lovely, iconic Ginkgo leaf is a familiar shape in art, craft and jewelry. Ginkgo have long been a favorite choice for bonsai.

Dwarf cultivars began appearing in the trade in the mid-1980s and there are now somewhere around 30 available in the U.S. As noted, Ginkgo is a monotypic genus. Thus, all cultivars come from one species, limiting the range of variation. Not all are reliably named or documented and many are so new that not much is known about growth rates, mature size and form, or even sex, as Ginkgo generally do not flower or fruit for 20-25 years. Whereas the species generally has a large, irregularly shaped crown, dwarfs come in a variety of shapes and sizes. Some are low and branching, others vase-shaped, columnar or pyramidal; some have different shaped or sized leaves. and one even has interesting bark formations.

Cultivation and Propagation

The cultural requirements of Ginkgo cultivars are similar to those of the species, and they generally all share the trait of buttery, golden autumnal color. The vast majority of cultivars originate as witch’s brooms, which Ginkgo produce with reasonable frequency. Two notable exceptions are ‘Gnome’, which originated as a chance seedling at Iaian Hiscock’s Commercial Nursery in Tennessee, and ‘Ross Moore’, which Ross Moore, of Moore’s Natives in North Carolina, found growing in a client’s garden.

The majority of named cultivars (except ‘Green Pagoda’, which, per its catalogue, Stanley & Sons grows from cuttings) are propagated by budding or grafting, with the scion wood of the desired plant grafted onto seedling rootstock of Ginkgo biloba. Lucille Whitman, of Whitman Farms in Salem, Oregon explains: “Much of the scion wood for dwarf Ginkgo cultivars is in short supply, due to the slow growth rate of the plants, their small stature, and their relatively short time in commercial propagation.

However, the good news is that if you can obtain the scion wood, grafting is easy and has a high success rate.” Due to this shortage of scion wood, many of the newest and sexiest cultivars are perpetually sold out and difficult to lay one’s hands on. Crispin Silva, of Crispin’s Creations Nursery in Molalla, Oregon, echoes Lucille’s frustrations about the scarcity of scion wood; he described building up a stock of scion wood as his biggest challenge in propagating Ginkgo cultivars.

Confusion in the World of Ginkgo

It quickly becomes apparent after talking with growers that there have been many new introductions over the last decade or so and very little documentation as to their specific growth patterns, growth rate, stability and variability. Add to that the scarcity of scion wood and the general slow growth rate of the genus, and you have a situation rife with approximation, hyperbole, and misrepresentation, even if much of it is unintentional.

A quick search of Ginkgo cultivars on the GardenWeb Forums, for example, produces pages of questions with incomplete, conflicting or unsatisfactory answers. Many of the cultivars have uncertain antecedents: for example it is not clear if ‘Chris’s Dwarf’ and ‘Munchkin’ are synonyms or not - two distinctly different forms have been observed. A similar situation arises with ‘Chase Manhattan’ and ‘Bon’s Dwarf’, with some claiming that they are the same plant, others that they are distinct and different.

There is also confusion surrounding the four or five offerings which originated at Spring Grove Arboretum in Ohio. One cultivar is named Spring Grove™, which is the trademarked name for a cultivar called ‘Grovbil’ (presumably a purposely un-euphonious shortened combination of Grove and biloba), which was originally termed Spring Grove #9. Thus, at one time or another, three different names have been applied to the same cultivar. ‘Grovbil’ only appears as a secondary name in the listing in the Spring Grove Arboretum catalogue - the plant is universally known as Spring Grove.

Another cultivar was originally named Spring Grove #86, but renamed 'Jehosephat'; another is called ‘Spring Grove Sport’ and another was recently registered as ‘Queen City’, which may or may not be the same as #22, which is referred to on several sites. ‘Queen City’, although a legitimate cultivar, is so new that an internet search comes up completely dry. There may be yet another not in commercial distribution.

Richard Larson, Nursery Manager of the Dawes Arboretum in Newark, Ohio and the North American Registrar for all conifer genera (once again, Ginkgo are included) expresses his frustration with the situation: “Registration is relatively easy and it’s free, but a lot of people don’t want to register plants, so we have Ginkgo coming out [which] were never registered. That means that there is a lot of anecdotal evidence about a number of dwarf cultivars, but no recorded information.”

He also notes that like certain other conifer genera, such as Taxus, Ginkgo are strongly plagiotropic, so that scion wood taken from different parts of the stock plant produces different growth patterns in the grafted product. This makes for differing growth patterns within one cultivar, raising questions about whether the plants are truly of the same name. Finally, due to lack of funds, the annual ‘checklist’, or perusal of the literature of a particular genus, which is supposed to be done on Ginkgo is not being completed, so that there is no current list of legitimately registered Ginkgo cultivars available, to serve as a guide as to which cultivars are “legit” and which might not be.

The Ginkgo's Battle of the Sexes

Because oddities are sought after by collectors (and consequently valuable), any indication of a different growth pattern is emphasized, although it should be noted that Ginkgo, their cultivar names or descriptions notwithstanding, do not display variable forms to the degree observed in other genera. When asked about weeping forms, for example, Richard notes: “No Ginkgo is going to weep like a cherry.” Similarly, Gary Handy, of Handy Nursery, when describing ‘Robbie’s Twist’, says that despite the fact that it is often described as “contorted”, “It is not a true contorted, like say a filbert or a corkscrew willow.” So, for those of you seeking the unusual, temper your expectations and remember that the dwarf Ginkgo are going to display more subtle modifications of the species habit than you might hope to find.

Another peculiarity of Ginkgo cultivars is that most people prefer male plants, due to the malodorous qualities of Ginkgo fruit, which is botanically not a fruit, but rather the fleshy outer coating of the seed. While some female offerings exist, selected and grown for those who appreciate the taste of the hard inner seed, the vast majority of named cultivars are male, or thought to be male. So, now we are down to one sex of one species, from which to produce cultivars!

In fact, because so much Ginkgo propagation is restricted to cloning male plants, there is thought to be some threat to the biodiversity of the genus. It seems odd that the sex of the plant should matter much with a dwarf, especially one that can take 20 years to bear, where the ‘fruit’ would be far fewer than on an enormous species tree, but “male” has become an important adjective in Ginkgo marketing. Therefore, male plants are promoted.

Muddling through Ginkgo Marketing Talk

Clarity is made more elusive still by the fact that many retailers include boilerplate language in their write ups, such as “flowers and fruit are not ornamentally significant”, which implies that the cultivar in question has fruit and is thus a female, when in fact it is a male cultivar. A quick Google search for any number of cultivars reveals exactly the same language on different retail - and in some cases wholesale - websites, indicating that many vendors simply copy (with or without permission) the descriptions supplied by others. One retailer, when contacted about the accuracy of the descriptions of his Ginkgo offerings admitted that they were written by a third party and he had no idea if they were correct or not!

In addition, most retailers, even the more knowledgeable, specialty nurseries, have a very short (and often very narrow) experience with dwarf Ginkgo cultivars, and so must rely on others to provide specifics about growth rates, habit and other particulars. When someone cannot speak from personal experience, there is far more opportunity for descriptions to get mangled. We have been playing the Ginkgo version of “telephone”, the old game where a phrase or word is repeated down a line of people until what the last person hears bears little resemblance to what the first person said.

Thus, a particular cultivar is described by different vendors as “columnar”, “irregularly branching” and “arching and curving” - surely contradictory! Given the difficulties, what’s a collector to do? Stay tuned for the next issue of the Conifer Quarterly, where we’ll share the results of our interviews with growers, retailers, arboretum professionals, and plantaholics with a list for those who want the most reliable selections…and further, choices for those who want to push the envelope!

Thumbnail photograph by Jerry Wang. Catalogue photographs by Harold Greer.

Click here to read about dwarf ginkgo trees and here for variegated ginkgos.