Woody > Juglans > Juglans ailantifolia > Juglans ailantifolia var. cordiformis
Juglans ailantifolia
var. cordiformis
Heartnut
Origin: Japan.
Mike's
Opinion
"
Juglans ailantifolia var. cordiformis is considered a “genetic sport” of the Japanese Walnut. It’s large, rich green leaves lend an exotic appearance reminiscent of the Tree of Heaven (Ailanthus altissima) from which the species gets its name. The Heartnut possesses lovely grey and tan bark in youth and showy flowers in the spring. True to its name, the tree also has heart-shaped nuts containing sweet, edible meat. Perhaps most important is Juglans ailantifolia var. cordiformis’s natural resistance to the butternut canker, which has devastated the native Butternut (Juglans cinerea) populations in North America.
Michael Pascoe, NDP., ODH., CLT., MSc. (Plant Conservation)
"
| Family |
| Juglandaceae |
| Genus |
| Juglans |
| Species |
| ailantifolia |
| Category |
| Woody |
| Type |
| Tree (deciduous) |
| Variety |
| cordiformis |
| USDA Hardiness Zone |
| 5 - 6 |
| Canadian Hardiness Zone |
| 5 - 7 |
| RHS Hardiness Zone |
| H7 |
| Temperature (°C) |
| -29 |
| Temperature (°F) |
| -20 |
| Height |
| 25 m |
| Spread |
| 10 m |
Photographs
Description and Growing Information
Flowering Period
| General Description |
| Lush, medium green foliage while the bark is an attractive grey and tan colour. The tree has a somewhat tropical appearance because of its large, compound leaves. |
| Landscape |
| Perhaps better suited for the larger landscape or commercial nut growing operations. Juglans ailantifolia var. cordiformis produces juglone which makes planting around the tree more challenging. However, its tropical appearance, showy flowers, and edible fruit make it a worthwhile consideration. |
| Cultivation |
| It prefers deep sand or clay loam soils with a pH of between 6 - 7; the tree does not tolerate heavy soils. It requires full sun and some protection from the wind in youth. Heartnut trees are "heavy feeders” and prefer some fertilization and irrigation. |
| Shape |
| Broadly spreading. |
| Growth |
| Medium |
| ID Characteristic |
| Large pronounced terminal bud surrounded by smaller secondary buds. It bears the largest leaves and produces more pollen than any other walnut. The seeds are a distinctive heart shape. |
| Pests |
| The major pests include butternut curculio, codling moth, and husk fly. The minor pests include leafhoppers and aphids. |
| Habitat |
| The tree is native to wet areas and by streams in Japan. |
| Bark/Stem Description |
| In youth the bark has somewhat smooth, grey ridges with a light yellow and tan colour in the shallow furrows. When mature the bark is darker, plated, and more furrowed. |
| Flower/Leaf Bud Description |
| The tree has a large terminal bud that is approximately 1.5 cm x 1.5 cm x 1.5 cm around and 2 cm tall. Three over-lapping bud scales are covered with fine hair. There may be one or more secondary buds around the terminal bud. The lateral buds are 0.5 cm tall and wide and are superposed above the leaf scar and are large and nub-like. |
| Leaf Description |
| The leaves are compound and oddly pinnate, they are opposite to slightly sub-opposite in arrangement. Leaf length is 76 cm with a petiole of 15 cm. There are 11 - 13 leaflets ranging in size from 9 cm to 13 cm near the petiole, and 18 cm to 22 cm near the terminal leaflet. The terminal leaflet is 17 cm in length and is obovate with no apex. The leaflets are oblong with acuminate apices while bases are oblique and the leaf margins crenate. Leaf colour is medium green and the texture is pubescent, including the petiole and rachis which are also sticky to the touch. |
| Flower Description |
| The trees are monoecious, male flowers form green catkins 30 cm long borne on older shoots while the female flowers erupt from the large terminal buds and are green and upright. Each female flower is 10 cm long and has up to 20 ovaries. The stigmas are either red or green tipped. |
| Fruit Description |
| Fruit is borne in clusters of up to 20 and is a sticky, green, and pubescent exocarp with a length and width of 4 - 5 cm. It contains tannins that stain or can be used as dyes. The endocarp is hard, smooth and cordate, 4.5 cm long and 3.5 - 4 cm wide and splits cleanly along one suture. |
| Colour Description |
| Leaves are medium green during the growing season and yellow in the autumn. Bark is grey and tan in colour but darkens with age. The fruit is green and the flowers are green and red. |
| Texture Description |
| These are medium textured trees. Leaves are pubescent, bark is furrowed but somewhat smooth to the touch but slightly coarser with age. |
| Notable Specimens |
| McDougall Line near Colley Drive, Rodney, Ontario, Canada. The Niagara Parks Botanical Gardens, Niagara Falls, Ontario, Canada. Westonbirt, The National Arboretum, Tetbury, Gloucestershire, England. |
| Propagation |
| Seeds are best sown in the autumn in deep pots in a cold frame. The seed germinates in late winter to early spring; plant permanently in early summer. Seeds can also be stored at temperatures between 1-4 °C or cold stratified for three to four months. Cultivars are best propagated through grafting and budding using black walnut or heartnut understocks. |
References
Grimo, Ernie. 'Nut Tree Ontario: A Practical Guide'. Niagara-on-the Lake: Society of Ontario Nut Growers, 2011. Print.
Coombes, Allen J. 'Eyewitness Handbooks: Trees'. Toronto: Stoddart Publishing Co. Limited, 1992. Print.
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