Aesculus, the buckeyes and horse chestnuts, comprise 13-19 species in the United States, Europe and Asia. Aesculus arguta, Texas buckeye, A. flava, yellow buckeye, A. glabra, Ohio buckeye, A. parviflora, bottlebrush buckeye, A. pavia, red buckeye, and A. sylvatica, painted buckeye, are reasonably well represented, at least in botanical gardens and arboreta from Minnesota to Georgia. Many of these species interbreed and hybrids are known. Aesculus californica, California buckeye, is a beautiful, white-flowered, broad-canopied tree found on dry hillsides in California. It is seldom cultivated in the eastern U.S., although pretty specimens are extant at the JC Raulston Arboretum, Raleigh, NC, and the Norfolk Botanical Garden, VA. The fruits/seeds are the largest of the U.S. species. I have grown and/or propagated all the eastern species, with A. flava, A. parviflora, and A. pavia sprinkled throughout our 3.5 acres, primarily in shady habitats.
The rarest species in the garden are A. chinensis, Chinese horse chestnut, which has yet to flower, and A. ×carnea, red horse chestnut, which flowered consistently the past 10 years, although considered ill-suited to the southeast. The tree was planted in 2013 and is now 15’ high and 12’ wide. Sited in full sun (by definition at least 6-hours), but on the north side of larger pines and oaks, it exceeded expectations. It is the result of hybridization between A. hippocastanum, common or European horse chestnut, and A. pavia, red buckeye. The hybrid is thought to have arisen in Germany as a spontaneous seedling. This means that the two parents were in proximity and the unscheduled wedding occurred, resulting in this magnificent, lustrous dark green leaved, rose-red-flowered, stately, medium-sized tree. I notice variation in the intensity of red flower coloration, so seedling trees, although purported to breed true-to-type, do not necessarily do so. I have collected seeds of the species but have yet to have a seedling flower. Aesculus flava seedlings produce flowers in their second and third years. To minimize thievery by squirrels, the fruits are collected when the outer, light brown, leathery husk starts to split. The seeds of A. ×carnea are polished brown-black and ¾ to 1-inch diameter. Seeds are planted immediately, covered with wire/netting to protect from varmints. Seedlings develop a taproot soon after planting; the shoot appearing immediately or the following spring.
In England and the European continent, the species is common, with mature trees hovering between 40 to 50’ high and wide. The red flower color is more intense there, possibly because of the cooler day/night temperatures. The largest trees in the U.S. are found in the northern states, not quite as prosperous/large in Zone 8, yet quite respectable. My wife and I host visitors/tours in May, and the A. ×carnea ‘Briotii’ (see under cultivars) is the most asked about plant. What is it and where can I buy one?
Aesculus ×carnea and A. hippocastanum are often maligned because of the leaf blotch (Guignardia aesculi/Phyllosticta sphaeopsoidea) which causes brown, disfigured, and tatty leaves in summer-fall. The disease does not kill the trees. I have found that A. ×carnea is less susceptible and, based on the 10 years in our garden, worthy of greater use from zone (4)5 to 8a. The Dirr tree is minimally affected by the blotch with leaves persisting into November. In Salt Lake City, UT, during an October visit, I noticed A. ×carnea and A. hippocastanum mixed in a street tree planting. The former clean; the latter riddled with leaf blotch.
The rose-red flowers are borne in 6 to 8” long, 3 to 4” wide terminal panicles in May. The tree flowers in late April into early May in Athens; a month later in the Boston area. The lustrous dark green, compound palmate leaves are composed of 5(7), 3 to 6” long leaflets, each with a slight undulating surface and serrated margins. Leaves may develop a tinge of yellow in fall. The buds, especially the flower (terminal), are ½ to ¾” long, and covered with dark chestnut brown, sticky scales. The stems are stout, gray; young trunks smooth and gray-brown; older becoming scaly and darker brown. The fruit covering has short spines, somewhere between the spiny fruit of A. hippocastanum and the smooth fruit of A. pavia.
The species is best adapted to moist, well-drained, acid or neutral soil, full sun to partial shade. Container and balled and burlapped trees transplant readily. Although the literature refers to lack of heat and drought tolerance, I have yet to observe leaf drop/browning.
‘Briotii’, known as the ruby red horse chestnut, is commercially available. It originated from seed in 1858 at the Trianon in France. Flowers are deeper red and borne on 10” long inflorescences. I encountered many trees labeled as ‘Briotii’ and the flower colors do not always match the description. The tree in our garden was purchased as ‘Briotii’ yet the flower color is pink-rose rather than red. Ideally purchase the tree in flower. I speculate that other A. ×carnea seedlings may have been labeled as such.
‘Fort McNair’ was selected for the increased resistance to leaf blotch. In Athens, I see little difference in susceptibility between this and ‘Briotii’. Certainly, a handsome tree and, without the label, I could not tell it from the Dirr ‘Briotii’. Selected on the grounds of Fort McNair, Washington, DC.
‘O’Neil’s Red’ has longer inflorescences (to 12”) and brighter red flowers than the above. A particularly beautiful tree grew in the Sarah P. Duke Gardens, Durham, NC, and flowered there in early to mid-May. Many spellings of the cultivar name. A reference mentioned ‘O’Neill Red’ was introduced by Monrovia Nursery circa 1979.
I believe an opportunity exists for intelligent/transformational breeding with Aesculus. The New World, A. pavia, serendipitously crossed with the Old World, A. hippocastanum; thus, other far-fetched species’ combinations may be possible. Hybrids of the eastern North American species like A. flava, A. glabra, A. pavia, and A. sylvatica are common and legitimized by GRIN taxonomy (see www.ars-grin.gov). Hybrids between A. parviflora and A. pavia would result in superb, pink-flowered offspring. I need to get back to the work at the breeding bench.
Carya species, hickory, native throughout the eastern, midwestern and southeastern United States, are seldom available in retail commerce. Primarily relegated to the deciduous forests, commingled with oak, beech, maple, tupelo and birch, few trees are more beautiful in autumn when aglow with the late developing, long persistent, rich yellow-gold foliage. Foliage shows significant frost/freeze tolerance in the range 24 to 28°F. I noticed hickories retaining fall color when adjacent species lost color or defoliated. From swamps (Carya aquatica) to mountaintops (Carya ovata) and sites between, a hickory resides. The nuts nourish all manner of wildlife and the pecan, Carya illinoinensis, is a major commercial tree, particularly in the southeast and southwest. There are ~18 Carya species and several hybrids. Eleven species occur in the U.S. with five of these extending into Canada. For a complete list of species worldwide, search germplasm research information network (www.ars-grin.gov) and plants of the world (powo.science.kew.org).
Leaves, flowers, and fruits
Hickories are tricky to correctly identify (ID), and hybrids make the process even more confusing. The following characteristics will lead the reader to the genus. After that, ID may become less clear/absolute. Leaves are alternate, compound pinnate with a central axis (rachis) and (3)5 to 19(21) leaflets, the terminal leaflet often the largest and obovate in outline; the lower leaflets oppositely arranged along the rachis. The leaf margins are serrate (toothed), surfaces pubescent or glabrous, and when bruised or crushed release a pungent odor.
Flowers are monoecious, meaning in separate structures on the same plant. Flowers open with the leaves, usually around mid-April in the Athens area (zone 8a). Male flowers appear in long cylindrical catkins from buds of the previous season’s growth. The apetalous female flowers occur on the emerging shoots of the season, either solitary or up to 10 in a cluster. The nuts that follow develop from a single ovary with two stigmas, the seeds appearing as two but joined at one end. The top-shaped, rounded, to ellipsoidal (pecan) shaped nuts are covered with a husk that typically splits along four suture lines. Fruits mature in October-November and the dehisced nuts are often evident under the tree. The seeds are high in unsaturated oils and serve as an important food for wild animals and birds. Pecan, C. illinoinensis, is an important commercial nut tree with a value of over 399 million in 2020.
Bud, stem, bark and wood
Winter buds vary from species to species and are described within the species’ descriptions that follow. Bark is likewise variable and the shaggy bark of C. ovataand C. laciniosa, is instantly recognized. Carya glabra and C. tomentosa are smooth barked in youth, developing ridged and furrowed bark with maturity. Tree bark of Carya aquatica is smooth in youth, then slightly roughened/scaley in old age. The wood of hickories is used for furniture, flooring, cabinets, veneer, tool handles, and for smoking meats. How many hickory trees have suffered because of ham and bacon? Worth mentioning from an identification standpoint that the stems of Caryahave solid pith, while Juglans (walnuts) have chambered pith. Split the first-year stem through the center longitudinally and the differences become obvious. Both reside in the Juglandaceae family and can be confused.
Propagation of Carya is principally by seeds and grafting/budding. The latter a common method for cultivars of pecan. Squirrels may be the best seed dispersal agents, for seedlings, particularly pecans, appear weed like in the southeast. I collect nuts in October-November, place several in well drained, bark medium in 3-gallon containers, cover 1 to 2”, and protect from animals with a screen. Seedlings require a cold period and are left outside. Germination takes place the following spring. The individual seedlings are then transplanted during the next winter to 3-gallon containers, the tap root pruned to half or more its length. I know a nursery that roots cuttings of Carya aquatica by harvesting juvenile shoots that develop after transplanting trees from the field. The holes are not filled, and adventitious shoots develop from the severed roots that remain at the edges. This method could be applied to other Carya species.
Carya species are adapted to wet (Carya aquatica), sandy/dry rocky slopes and ridges (Carya tomentosa), and silt loam to clay (Carya glabra, Carya laciniosa, and Carya ovata). If they were easy to transplant, hickories would be available in greater numbers. Hickories are essential components of the North American deciduous forest ecosystem and, with oaks, maples, birches, tupelos, elms, walnuts, tuliptree, beech, and sweetgum, command and deserve to be planted and preserved.
I recommend purchasing small bare-root seedlings or containerized material. Several growers/retailers from whom I purchased hickories and other native trees include Superior Trees, Lee, FL (superiortrees.net), Mail Order Natives, Lee, FL (mailordernatives.com), Forrest Keeling Nursery, Elsberry, MO (fknursery.com). Hillis Nursery Company, Inc., McMinnville, TN, (hillisnursery.com) offers six Caryaspecies. Melanie Wells, Mount Vernon, provided additional online nurseries that supply Carya species (americanheritagetrees.org and whitehousenatives.com).
The best adapted and available Carya species for garden and native plantings include the following.
They are presented by bud and leaf characteristics. Carya aquatica, C. cordiformis, and C. illinoinensis have valvate terminal buds meaning the bud scales meet at their edges but do not overlap, the terminal larger than the lateral buds. The leaflets, the same size throughout.
Carya glabra, C. laciniosa, C. ovata, and C. tomentosa with bud scales overlapping. Leaflets fewer, the terminal leaflet larger than the laterals, often 2 to 3 times. Terminal buds larger than laterals.
Carya aquatica, water hickory, is a beautiful tree with finer textured foliage and branching habit than those that follow. There are typically 9 to 11, 2 to 3” long, equal sized leaflets. Leaves are rich green, turning soft to bright yellow in autumn. I noticed leaves still persisting on trees in Athens as late as mid-November. The nut is 1 to 1 ½” long, broadly ovoid, and four-winged along the seams. The kernel is bitter. The rich brown bark develops scaly plates, not as prominent as those of C. laciniosaand C. ovata. I noted a 70’ high tree at the Coker Arboretum, University of North Carolina, Chapel Hill. National champion is 97’ by 62’. Common in swamps and along rivers from Virginia to Texas. This has been the easiest hickory to transplant balled-and-burlapped. Zone 6 to 9.
Carya cordiformis, bitternut or swamp hickory, has seldom crossed my path, although native to every state (except Maine) east of the Mississippi and nine contiguous states west of the mighty river. I remember trees at Middlebury College, Vermont, University of Illinois, Champaign-Urbana, IL, and in June 2022, Mount Vernon, VA. Initially, I was not positive about the identification of the Mount Vernon Carya, until Melanie Wells, horticulturist, sent a photo of the sulfur yellow buds. The branches were so high, I could not accurately count leaflet numbers (typically 7 to 9, ~equal size) or determine bud color. Melanie mentioned that the tree was previously identified as C. tomentosa. The light green, slightly falcate leaflets are 3 to 6” long, ¾ to 21/2” wide, turning rich golden yellow in fall. The suborbicular nut is 11/4” long, 4-winged or ridged, often only above the middle, the seed bitter. Typically, a slender tree with an irregular, cylindrical crown of stiff ascending branches, widest at the top. This habit description could be superimposed on the Mount Vernon specimen. Bark is gray-brown, smooth initially, developing low narrow interlacing ridges, occasionally with a few scales. I estimate 50 to 75’ high, slightly less in spread. National Champion is 106’ high and 100’ wide. Considered the fastest growing of the hickories. In the wild, most often found in low woods, less frequently in uplands, although the USDA profile describes it being found on rich, loamy or gravelly soils, low wet woods, borders of streams, and dry uplands. Zone 4 to 9.
Carya illinoinensis, pecan- Although not native in Georgia, it is major cultivated nut crop with a value of 182.5 million in 2021. Seedling trees are like mushrooms and appear everywhere, producing reasonable quantities of edible nuts. The modern pecan industry relies on improved cultivars and thousands of acres were planted in the last 10 to 15 years. Leaflets vary from 11 to 17, each 4 to 7” long, 1 to 3” wide, the midvein slightly curved, resulting in the term falcate. About the easiest Carya to identify by foliage. Leaves are lustrous dark green, persisting late into November (Athens), occasionally with a wisp of yellow fall color. The thin-shelled, ellipsoidal, brown nuts, tapered at their ends, average 1 to 2” long and are held in a four-valved, winged, dehiscent husk. Nuts dehisce in November in the Athens area and can be readily gleaned. Plant in moist, well drained, deep soil, although stray seedlings take hold under myriad conditions. The lateral buds resemble toasted almonds in shape and color. They are held at 45-degree angles to the stem. Bark is gray-brown, somewhat scaly on mature trunks. A large tree, 70’ and beyond, and certainly not for small properties. National champion is 97’ by 106’. In nature, the species inhabits low areas along water courses from Indiana to Texas. Zone 5 to 9.
Carya glabra, pignut hickory. I grew up with this species in southern Ohio where it was quite common. It has a tapering trunk and a regular, open, oval head of slender contorted branches. Finer texture than C. laciniosa, C. ovata, and C. tomentosa. Leaves are composed of 5 to 7 (typically 5), lustrous dark green leaflets. Each 3 to 61/2” long, 1 to 2” wide, the lower pair one-third the size of the terminal. Leaves turn beautiful golden yellow in fall. Nuts are subglobose, ¾ to 11/4” long, the seeds with a bitter taste. The bark is smooth, gray-brown on young trees, eventually developing rounded ridges, intersecting to form a diamond shaped pattern. Landscape size approximates 50 to 60’ high and 25 to 35’ wide although the National Champion is 149’ by 75’. Common in nature in drier habitats, upland soils, and rocky areas. Zone 4 to 9.
Carya ovata, shagbark hickory, is one of my favorite Noble Trees which should be planted in every park, golf course, open area from Canada to Florida and west to Missouri and Texas. The bark, composed of gray-brown shaggy scaly plates, free at both ends, curving away from trunks, makes for easy identification. The deep green leaves, comprised of five, rarely seven, 4 to 6” long, ½ to 21/2” wide leaflets, turn saturated golden yellow to golden brown in fall. Nuts, nearly round, 1 to 11/2” diameter, shell angled, husk ¼ to 1/3” thick, freely splitting at maturity, no winged suture lines, enclose edible, sweet seeds. Shelled shagbark hickory nuts sell for $9.99 per ounce or $19.99 dollars for three ounces from hickorynutsdirect.com. Species develops a straight, cylindrical trunk, with an oblong crown of ascending and descending branches (like C. laciniosa). In the wild, is found in drier upland slopes and deep well drained soils in lowlands and valleys over most of eastern North America. I have observed magnificent trees in urban, suburban and natural areas. Have yet to be disappointed by performance. Estimate 60 to 80’ high. National Champion is 104’ by 99’. Zone 4 to 8 (9).
Carya laciniosa, shellbark hickory, differs from C. ovata in leaflet number, primarily 7, and the absence of tufts of pubescence (hairs) near the tips of serrations. Buds, bark, nuts (sweet seeds) are similar. Safe to state, I am never sure about positive identification between this and C. ovata until examining the leaves. Estimate 60 to 80’ in height; the National Champion 109’ by 112’. Found in bottomlands and floodplains, New York to Alabama to Missouri and Arkansas. Not as common as C. ovata. Zone 5 to 8.
Carya tomentosa, mockernut, white hickory, is a common species over most of eastern North America. The leaves and stems are covered with brown pubescence which persists and permits easy identification. The leaves are composed of 7 to 9 leaflets, the upper pair 5 to 9” long, 3 to 5” wide, the lower pair two-thirds that size. Leaves are dark yellow green, fragrant when bruised, and develop deep golden yellow to golden brown fall color. Nuts are elliptical to rounded, 1 to 11/2” long, angled, with a ¼ to 1/3” husk splitting to the base. The seed is edible. Habit is narrow to broadly rounded. The bark develops interlacing ridges forming a diamond to netlike pattern. Common to dry habitats of uplands, including ridges and hillsides. To 3,000’ in the southern Appalachians. I estimate 50 to 60’ high under landscape conditions. Many trees in the Athens area supersede this size. The National Champion checks in at 140’ high and 85’ wide. Zone 4 to 9.
The other U.S. species are C. floridana, scrub hickory, C. myristiciformis, nutmeg hickory, C. pallida, pale or sand hickory, and C. texana, black hickory.
This mini treatise will hopefully inspire readers to become familiar with Carya, hickories. They are remarkable Noble trees that for too long have flown under the landscape radar. I believe the Chinese Proverb, “The best time to plant a tree was 20 years ago; the next best time is today”, applies to hickories. In my 78th year, I planted a Carya aquatica grown from seed collected at the USDA Germplasm Repository in Beltsville, MD. The quote, “The true meaning of life is to plant trees under whose shade you do not expect to sit”, rings true for my effort.
Cornus is a fascinating genus with species ranging from groundcover habits (Cornus canadensis) to large trees (Cornus controversa). I relate to students and garden visitors that if one dogwood is recognizable, then all can be. The leaves (primarily deciduous, several evergreen) are linear-ovate to ovate to broad ovate, margins entire (no teeth) with veins originating from the midvein and then turning toward the apex, almost paralleling the margin. When the veins are and gingerly teased apart, rubbery strands are evident. Cornus alternifolia and C. controversahave alternately arranged leaves; all others opposite. Now the trick is to accurately identify the ~60 species.
The red buckeye is among the most beautiful eastern North American tree species, especially in flower, when the brilliant red panicles glow in the woodsy understory. The species occurs naturally in pinelands, pine-deciduous woods, wooded bluffs, stream banks and bottomlands throughout the range. The USDA Plants Database shows distribution in the wild from North Carolina to Florida west in an arc to West Virginia Kentucky, southern Illinois, southeast Missouri dipping into Texas. I observed numerous plants along coastal South Carolina and Mobile Bay, Alabama, growing in sandy soils. Based on the southern distribution, one could assume lack of hardiness, yet plants in gardens and arboreta survived -20°F and below. Spring Grove Arboretum, Cincinnati, OH, has many beautiful specimens that have experienced below -20°F through the years. The species is successful at the Morton Arboretum, Lisle, IL, which in the 2018-19 winter recorded -24°F. The Minnesota Landscape Arboretum, Chanhassen, MN, grows ‘Atrosanquinea’, a bright red-flowered cultivar.
The species is utilized as an understory plant in the Dirr garden, residing in the towering canopy of white oak, tupelo, and sweetgum. In this shade environment, trees are smaller and more open. Flowering is moderated a degree but still respectable. The habits of open-grown trees vary from oval-rounded to rounded, usually clothed with dense branches and large compound palmate leaves. Landscape size ranges from 15 to 25’ in height with similar spread. The National Champion (2019) was 48’ high and 37’ wide and resided in St. Louis, MO. I was asked many years past how I determined tree sizes in the Manual of Woody Landscape Plants. I typically reduced champion sizes by 50%. Not a bad rule of thumb for landscape sizes.
The foliage is beautiful, especially the early emerging leaves in riotous colors of green, purple-green, purple, yellow, orange, red, bronze and other permutations (see photo). The effect is ephemeral for the foliage soon becomes shiny dark green. Fall color is yellow at best, assuming there are persistent leaves. The anthracnose/blotch often defoliates trees by late summer. Each leaf is composed of 5 to 7, doubly serrate leaflets, to 6” long.
Flowers, pure red in the best incarnation, open with the emerging foliage in late April (Athens). They remain effective for two weeks or longer, depending on temperatures. The individual tubular flowers, 11/2 to 2’” long, are borne in a 6 to 8” long panicles at the ends of the shoots. Flowers are pollinated by the ruby-throated hummingbirds. A tree in resplendent flower is the tonic of spring. Red buckeye hybridizes with A. flava, A. glabra, and A. sylvatica, the result a mixed bag of flower colors.
The fruit is a large, smooth-skinned dehiscent capsule with one/two shiny rich brown seeds. As soon as the capsule starts to split, they should be collected and the seeds removed. Plant immediately as seeds will quickly wither. I sow seeds in 3-gallon containers filled with pine bark, cover with one-inch of bark, protect from predators, and leave outside. The root radical emerges soon after planting; the shoot the following spring. The seedlings are divided in late fall, tap root pruned, and transplanted to 3-gallon containers. The seedlings often flower in the second or third year.
Certainly, an adaptable species and can be grown in acid or high pH, sandy to clay-based soils with moderate moisture. Does show drought stress and requires supplemental water. The worse-case scenario is the leaves abscise but the tree bounces back the next year. I wish the species were more available in garden center commerce.
Aesculus pavia and A. hippocastanum hybridized in cultivation, largely without the hand of the breeder, to produce A. ×carnea, the red horsechestnut, and the cultivars ‘Briotii with deeper red flowers, ‘Fort McNair’ with lighter pink flowers and greater leaf blotch resistance, and ‘O’Neil’s Red’ with close to red flowers. ‘Briotii’ is one of Bonnie’s favorite flowering trees, consistently flowering in the garden since planting in 2013.
I have always loved the buckeyes and horsechestnuts and perhaps this small essay with inspire others to engage with the genus.
Chionanthus retusus- Chinese fringetree
Michael A. Dirr
In 2018, I was asked to assist with our county’s (Oconee, Georgia) tree planting project for a new four-lane, 3.5-mile highway. The county commissioner emphasized the concept of a tree-lined gateway to the county seat, Watkinsville. After many meetings, nursery visits and suggestions, we agreed upon 760 trees, comprising 51 different species and cultivars. The landscape architect sited the trees to minimize underwire issues, sight-line intrusion, and space allocations (medians). Locating diverse small tree species, 15 to 30’, was difficult and redbuds and dogwoods were overplanted, with more loses than I expected. One superlative addition was Chionanthus retusus, Chinese fringetree, the only regret, we did not use more. Chionanthus viriginicus, the native white fringetree, was presented in a previous HMI article/blog. It was included in the project and has prospered.
There are 60 Chionanthus species widely distributed in the tropics with only the above two species temperate zone cold hardy. Chionanthus retusus occurs in mixed forests, thickets, and along rivers in China, Korea, and possibly Japan. In cultivation, it forms a broad-rounded to spreading outline, often with long splaying shoots. I observed permutations in habit from vase-shaped to columnar (‘Tokyo Tower’). I estimate the species landscape size between 15 to 25’ high and wide. The bark on young trees is exfoliating/curling; with age and size, ridged and furrowed, the ridges flat and gray, the furrows, deep brown to black.
Foliage is 2 to 3” long, rounded in outline on ‘China Snow’; 6 to 8” long and narrow elliptic on ‘Arnold’s Pride’. Typically, deep green to glossy dark green in summer and tremendously heat and drought tolerant. Fall color, soft yellow to golden yellow, develops late (November-December), remaining effective for many weeks. The foliage is freeze resistant to at least 25°F.
The flowers are borne in 2 to 3” high, 2 to 4” wide panicles, mid to late May, Athens (zone 8). The flowers occur at the end of the new season’s shoots and shroud the canopy in a fleecy dome of snow; effective for several weeks depending on temperatures. The sexes are separate (for most part), thus fruits may or may not be present. The fruit is a dark blue, ½” long ovoid drupe, the outer covering fleshy, the inner a stone-like seed. Fruits ripen in September-October and persist longer than those of C. virginicus. Birds have stripped C. virginicus on campus while fruits of C. retusus persisted into late fall.
The species is well adapted to extremes of soil, except wet. Acid, alkaline, clay-based, and droughty (once established) are fair game. For maximum flower effect, site in full sun, yet plants in shade are effective. The species transplants readily and is available container-grown and balled and burlapped. Hardiness is open to question with zones 6 to 8 (9) suitable. I suggest -15°F will seriously injure plants, although a 30 to 35’ high specimen, grown from seed collected by E. H. Wilson, has been growing for over 100-years in Boston’s Arnold Arboretum.
The species has thrived in the highway setting and has generated questions about identity. It is an excellent under wire tree and with new cultivars available serves as an alternative to time-honored redbuds and dogwoods.
‘Arnold’s Pride’ is mentioned above. Vase-shaped outline with longer/clearer trunk and suitable for street tree use. Now in commerce and available from Pleasant Run Nursery, New Jersey.
‘China Snow’ is the thick-textured, glossy dark green leaf, profuse flowered selection developing a rounded outline with a low-branched trunk. Fits the 15 to 25’ high and wide size category. Named by don Shadow, Winchester, TN. Reasonably common in commerce.
‘Tokyo Tower’ is a more or less columnar form, slightly wider at the top, creating a narrow vase-shape silhouette. The 11-year-old plant in the Dirr garden is 24’ high and 8’ wide. Did not produce many flowers until the 6th year and then primarily in the upper branches. A superb choice where lateral space is limited.
Other cultivars include ‘Ashford’, ‘Confucius, and Spirit® (‘CRN10’).
In previous tree profiles, I discussed Magnolia acuminata and M. × soulangeana and herein highlight an increasingly important landscape species, M. viginiana. It is becoming more common in contemporary landscapes because of new cultivars with smaller sizes, increased cold hardiness, and fully evergreen foliage into zone 6 landscapes. The impetus for this discussion resulted from the August 5, 2020 visit to Apalache Nursery, Turtletown, TN. The owner, Keith Kilpatrick and his son, Taylor, have been long-time friends and native tree aficionados. The nursery nestles in a beautiful, unspoiled Brigadoon-type valley with visitors only allowed every hundred years (It was the 100th year anniversary). Bonnie commented the setting was one of the most pristine places she had ever experienced (photo). Keith and son specialize in trees and shrubs grown from wild-collected local seed. Magnolia virginiana ‘Apalache’ is their cold hardy evergreen selection, leaves lustrous dark green, clothed with branches to the ground, 20 to 25’ high. The remarkable aspect of the cultivar is the consistency of habit and foliage when grown from seed (photo, ‘Apalache’). I have grown many seedlings of the species with nothing akin to the parent. In fact, a recent seedling population derived from Keltyk® yielded small- compact and loose-open habits; tiny leaves to semi- tropical foliage (photo).
Magnolia virginiana grows in moist to wet soils, often in swamps, from Massachusetts to Florida, west to Texas, and inland to Tennessee, Oklahoma and Arkansas. In Weeks Bay Wildlife National Estuarine Research Reserve, AL, trees with trunks as large as oaks grew in the swamp next to M. grandiflora and Q. michauxii.
Landscape size is in the 30 to 50’ height range; less in width. National Champion is 115’ high and 66’ wide and resides in Jefferson, FL. Trees are single to multiple trunked, gracefully pyramidal-oval in youth, broad-oval at maturity. The foliage, bright to shiny dark green, the undersides silver-white, provide refined and billowy auras, especially when buffeted by the wind. Leaves range from 3 to 8” long, one-third to one half this in width. The deciduous types may develop pretty yellow fall color. Young stems are light green and when bruised/scraped emit a sweet lemon fragrance. Bark on large trunks is smooth, gray, and similar to beech bark.
Flowers appear in April in zone 8; a tree at the Coastal Maine Botanical Garden, Boothbay, ME, is flowering in October. Flowers develop on old and new growth of the season for several months. Each glistening white, 2 to 3” (4”) diameter, exceedingly fragrant, composed of 9 to 12 tepals (petals and sepals similar in shape and size). The knobby 2” long and wide fruits turn dark red, the red seeds emerging from the follicles on a slender silver thread. Seeds can be collected at this stage, soaked in water, the pulp removed, placed in moist medium in plastic bags, and cold stratified for 2 to 3 months. Seeds often germinate during the cold period; the white root radicles evident. Remove and transplant to suitable germination media.
The species, although native to swamps, will tolerate drier soils, especially once established. I observed chlorosis on plants in the Midwest. A pH range of 5.5 to, shouldering on 7, is suitable. Trees are produced in containers and balled and burlapped. Growth is fast, especially young seedling trees, which easily reach 6’ and more in a season. As a single specimen it develops into a pretty tree. Useful as a patio or large container element. I noticed groupings and rows of trees for screening. On the Georgia campus it has been used to shadow and soften blank-walled buildings. During nursery visits, increased production is evident as the landscape architecture profession has embraced the species for multiple uses.
Most exciting is the number of cultivars introduced in the 21st century. I have grown/observed the following.
Emerald Tower® (‘JN8’) is upright, more compact, with glossy green foliage. 20’ by 8’. Ray Jackson introduction, Tennessee.
Green Mile™ (‘MVHH’) develops a graceful pyramidal habit with long narrow shiny dark green semi-evergreen to evergreen foliage. Size 35’ by 15’. Selected by Alex Neubauer, Hidden Hollow Nursery, TN.
‘Green Shadow’ was fully evergreen after exposure to -20°F. Named by Don Shadow, Winchester, TN. 30 to 40’ high to 20’ wide.
‘Henry Hicks’ is one of the earliest hardy evergreen selections. I have grown it in the Georgia garden and although evergreen, it has been a slow mover. Estimate 30 to 40’ high; 20 to 30’ wide.
Keltyk® ( ‘MVMTF’) has smaller foliage, more compact habit and is completely evergreen, 20 to 30’ high, less in spread. I love this selection. More refined in foliage and habit. Introduced by Moon Tree Farm, GA.
Moonglow® (‘Jim Wilson’) is a larger, loose-growing selection with dark green, semi-evergreen foliage. Matures at 35 to 40’ by 15 to 18’. Survived -28°F without injury. Beautiful plant and widely available in commerce.
‘Northern Belle’ sports darker green leaves then Moonglow® and survived -35°F. 25’ high by 8 to 10’ wide.
‘Santa Rosa’ has the largest evergreen leaves of any cultivar. Selected from a Florida seed source so best in zones (6)7 to 9. More wide spreading than others. 25’ by 20’.
With the loss of Fraxinus, ash, to emerald ash borer and no resistance among the 22 U.S. native species; the uncertainty of long term performance of disease-resistant American elm cultivars; and the invasive issues attached to Norway maple and other species, new tree genetics are necessary.
I first witnessed 20 to 30’ high trees at Longwood Gardens in 2012/13 and actually begged for a few seeds. Was rejected on the basis that the species was collected in the wild from China and the host country needed to be reciprocated (assume with royalties), so could not share material. Continued sightings at the National Arboretum, Arnold Arboretum, Morris Arboretum and a west coast nursery indicated the species was being shared/distributed (without concern for reciprocity). All trees observed to date were higher than wide, similar to Tilia cordata in habit, the largest trees 35 to 40’ high. In its native habitat, trees reach 80 to 100’. I estimate 40 to 60’ by 30 to 40’ wide under cultivation.
Bark is quite remarkable, akin to that of Acer griseum, paperbark maple, exfoliating in curls and papery sheets. Colors range from light brown, copper-brown to deep chocolate-brown. Exfoliation occurs on two-year-old stems through large trunks. The tree is more beautiful in winter than in leaf.
Leaves are 2 to 4’’ long, 1 to 2’’ wide. Medium green, turning yellow in fall, shaped more like an elm leaf than the typical rounded Corylus outline. Foliage has shown high heat and drought tolerance. The summer of 2016 in Athens, GA was the hottest on record with no rain for extended periods. Two, four-year-old trees in the Dirr garden showed no foliar stress.
Flowers occur in March on naked stems; the male in drooping 2 to 4” long, reddish brown catkins; the female barely visible at the tip of the bud. Fruit is a 1/2” diameter hard-shelled, edible, globose nut held in a 2 to 4” long tubular sheath (involucre). The Morris Arboretum shared numerous nuts with the author which, 4 years later, are still germinating. I continue to manipulate the pre-germination treatments that will produce uniform percentages. Seedlings grow rapidly, 4 to 5’ in a season. Cuttings have been almost impossible to root.
To date, Japanese beetles have not been an issue (a problem on Corylus). No foliar diseases or insect damage have been observed/reported. The species is resistant to eastern filbert blight, a fungal pathogen which devastates Corylus avellana, especially ‘Contorta’, Harry Lauder’s walking-stick.
The species is cold hardy in the range of -20 to -25 F and is well adapted to zone 8, Athens-Atlanta. Trees in Chicago, IL, Boothbay, ME, Boring, OR, and Athens, GA attest to adaptability. Any well-drained soil preferably on the acid side is suitable. Trees in heavy shade are more open than those in full sun. Container-grown plants are easily transplanted.
The tree is available in commerce. Grafting and budding have been successful as has tissue culture propagation. Several vendors include Heritage Seedlings, Salem, OR and J. Frank Schmidt Nursery, Boring, OR.