Essays

by Keith Johansson

Rooted Cutting.JPG
 
 

"Growing the Shantung Maple in Texas Conditions"

written by Keith Johansson for The Maple Society newsletter, published Summer, 2006.


Acer truncatum, Shantung maple, is thriving and gaining popularity in difficult situations, like the Dallas/Fort Worth, Texas area. I began commercially growing fifty plus varieties of Japanese, Shantung, and other maples in Fort Worth in 1994 under the name Metro Maples, but now I love the Shantung maple because of its toughness, good growth, and year-round beauty. Dr. John Pair, Director of Research, Kansas State University, told me back then at an American Rhododendron Society meeting that I should grow Shantung maples. He was one of the most respected horticulturists in the country and did the initial research on the tree in Wichita, Kansas from seed sent from the Morris Arboretum. Not only does Wichita get hot but it also receives severe cold snaps and strong winds. Many reports on the Internet claim the Shantung maple is cold hardy to at least minus 25 degrees Fahrenheit. In early December 2005 none were damaged by a sudden change from 90 degrees to 14 degrees, while many Japanese maples were damaged or killed.

Initially, Shantung maples were hard to sell, as nobody knew what they were. To me it seemed like a tough and beautiful tree but many thought it might be another Silver maple that falls apart quickly in my area. By year 2000 the Shantung maple and only two other trees were on the Texas A&M University Superstar list and sales took-off.

I have grown approximately 9,000 Shantung maples, which seed comes from China with a climate similar to New York. They are easy to grow from seed. Shantung seedlings have grown fast in the first year but lately they have grown slowly. I believe recent seed was harvested too soon. The average person with an established tree will get growth of 2 to 5 feet per year even in the alkaline black gumbo soils of Dallas or the white caliche soil of Fort Worth.

They are extremely drought tolerant as I have watched several survive without water during my very long and hot summers in my sandy soil. In my area they do require irrigation for the best growth. In summer 2000 I went 110 days without any rain. Last year was the worst drought in fifty years and I began watering my larger trees in summer, once a month to maintain good health. I have grown thousands in full sun in black pots on black plastic and can get new growth, which does not burn, from April until the first of September. Shantung maples must like it hot and somewhat dry as my extremely sandy soil never holds any water and dries-out very quickly and because for me they reach over 20 feet in 7 years!

The only native maple in my area is Acer negundo but is not a tree for most people. To the east and southeast where soils are acidic and rainfall more abundant is Acer rubrum and Acer saccharum spp. floridanum. To the south is Acer saccharum ssp. grandidentatum. In western Oklahoma there is a sugar maple that has survived the millenniums in a small canyon that is called the Caddo Maple. These all grow for me but are slower and are not quite as showy or as tough as the Shantung maple.

Shantung maple branches are flexible but old wood is very hard, much like an oak. They can grow in windy sites. Kansas State University proclaims them also as one of the best performing trees in ice storms. The bark is two-tone brown, heavily fissured and very attractive. The root system reminds me of a Japanese maple and is not overly aggressive or shallow rooted. They tolerate pollution and fit the typical urban landscape. About the only thing they cannot tolerate is poor drainage.

The bright lemon yellow flowers are produced in corymbs and this year one large tree had flowers for 10 days before the leaves emerged. Usually the flowers appear only a couple of days before the leaves. So far it appears that most seeds do not develop for me but this means that the tree is also not weedy.

Spring and summer new growth is usually a reddish-purple, but reds and oranges are also seen. Fall color is a very bright yellow on about 90 percent of the trees. Sometimes reds and oranges are mixed with the yellow. Sometimes they are all red or orange but return to yellow the next year except for a new introduction I call Acer truncatum 'Fire Dragon'. This tree has always had red fall color. The other reason I choose to patent and propagate this variety is the beautiful leaf shape (see photo). 'Fire Dragon' has smaller leaves that are seldom truncate and have backward angled basal lobes, lobes with prominent teeth, and do not have the larger central lobe that is typical of most Acer truncatum. The size and shape of the leaves give the tree a cleaner look. Summer growth can be a burnt orange or pink or bright red depending on the nutrients and the amount of water. Fall color is a cardinal red (RHS 822/3), or when I don't have cool temperatures it is a currant red (RHS 821/3) with striking Chinese yellow (RHS 606/1) around the margins. 'Fire Dragon' also appears more heat tolerant as it has a good ability to keep healthy new growth without wilting under extreme heat conditions. What seems so amazing is that 4 years ago I had just one small mother tree, and now I have over 3,000 of them!

One of my first Shantung seedlings I grew is now 12 years old and turned out to be a nice little dwarf. It is always growing, trying to be big, but is only 3 feet tall by 3 feet wide. Its leaves are only 1 inch wide and new growth is a very attractive orange-red all summer. I call this tree, 'Baby Dragon.' I have no plans for production but I do have some safely tucked away in another location in case a tornado takes mine out.

I am also testing two yellow fall color cultivars. One has very narrow and wavy leaf lobes giving the tree a delicate appearance. This one is called 'Skinny Dragon.' The second tree produces a high percentage of beautifully shaped leaves with backward angled basal lobes and teeth on all the lobes, which is known as 'Golden Dragon.' All Shantung maples have polymorphic leaves in varying percentages. These two are not any better or worse for fall color its just the beautiful leaf that is desired. There are also several other interesting leaves that I have found including one that has deeply cut lobes with side lobes that curl downward, (see photo). My seeds produce leaves that are similar in shape to 'Golden Dragon' about 30 percent of the time. Hopefully, soon I will find a dissected leaf. I have two new variegated seedlings under review. One does not grow much at all and we'll see what the other does. Recently I grafted an Acer platanoides 'Crimson King' onto a Shantung rootstock to see if this tree will then grow in our area. I've thought about what I could hybridize a Shantung maple with but there aren't many improvements needed.

Texans love fall color. Unfortunately the native trees, mostly oaks, hackberries, cottonwoods and pecans have poor fall color. They love Japanese maples but they must be shaded and carefully watered. Shantung maples act like a native and turn brilliant colors every fall. I am now planting Shantung maples all over the farm so when I retire they'll be ready to put on a really big show that you'll have to see to believe.


"New Acer truncatum Cultivars"    

written by Keith Johansson for The Maple Society newsletter - published Winter 2011  

I never dreamed that the range in sizes and colors of Acer truncatum would be so vast, and in the beginning never went looking for new cultivars but they came looking for me.  I have been growing Shantung maples for 17 years and now have 17 distinct Shantung maples that are grouped into categories:   red or unusual fall color, dwarfs, mid size less than 15 feet (5m), columnar, yellow leaves, and variegated.  Here are two new cultivars to complement 'Fire Dragon' Shantung (PP #17367) that I introduced in 2006.

Acer truncatum 'Baby Dragon' (PPAF) was discovered in 1994 and despite its fast growth is only 5 feet tall and a little over 6 feet wide (147.3 cm x 185.4 cm).  This dwarf has a weeping habit as the thin branches are unable to hold up the vigorous and dense leaf growth.  Caliper is just 2 inches (5.1 cm) and the bark is not heavily fissured.   Bark color is light gray, almost white, due to its slow caliper growth rate.  Average leaf size is less than 1 inch (20.2mm x 23.1 mm) and a light green on both sides.  It is never a dark shiny green like most Shantungs.  The veins on the underside are more prominent than usual, in part due to their relative size compared to the leaf size.  The 5 lobes are slightly wavy with margins entire and triangular ovate lobes broader at the bottom and deeply cut two thirds of the way to the leaf base.  Some bases are truncate but the majority is shallowly heart shaped.  The petioles are slender and a short .7 inch (17.7 mm), and maintain a light pink color on the upper side.  Milky sap is produced when broken.  Flowers or fruit have never occurred on 'Baby Dragon' but I expect the faster growing grafts to eventually produce seed.  A 4 year old graft is already 4 feet by 5 feet.

New growth colors are easily produced and are rusty deep pink to vivid strong pink. (Ed. - Photograph of 18 month old grafted plant in July).  Fall colors are a very bright yellow and red.   This maple is heat and sun tolerant, and like 'Fire Dragon' has shown an exceptional ability to avoid damage from early or late hard freezes when in full leaf. 

Acer truncatum 'Super Dragon' (PPAF) was discovered in 2006 and has a brilliant yellow green leaf with light yellow green veins that appear white.  Each spring the leaves unfold a moderate red orange with light orange yellow veins.   Summer growth colors are bright pink, orange, or red, all with light yellow green veins.   The yellow color never fades but deepens a little into summer.  Unlike other yellow leaf trees it does not easily burn, even in the hot Texas sun.  Fall colors are a bright yellow with red.

'Super Dragon' has a slightly smaller than average leaf size with truncate bases and wavy margins.  The central lobe usually produces large, broad triangular teeth that also can occur on one or both neighboring lobes.  This cultivar has identical leaf colors on both sides.  Current year wood and petioles also display the leaf colors.  Winter shoots and buds may have yellow and red color but of a darker tone.  Like other Shantung maples it is a low branched, shrubby tree but is easily trained into a straight trunk.  The growth rate on this cultivar is a little below average so I expect this cultivar to have a smaller mature height of about 25 feet (8 m).   'Super Dragon' should be hardy like other Shantung maples, and along with 'Baby Dragon' will be important parents in my hybridizing program of straight Shantung maples.