NUT TREE GROVE
What is a nut tree?
Nut trees are a group of woody plants that produce a nutrient rich, edible seed as part of their reproduction. Many of these species evolved with animals, which are responsible for planting new nut trees. For example, many of our native hickories and walnuts rely on birds and mammals to collect nuts, cache or bury them, and then forget where they were stored. The next spring, the forgotten nut will germinate and grow a brand new tree! Many nut trees are considered mast species, meaning the go through waves of highly productive years creating lots of nuts, and years of less production where they focus on growing. Humans have been using nut producing species for thousands of years, and they have become an irreplaceable food source for much of the world.
Despite popular belief, nut trees are a diverse group of trees from several different plant families. For instance, almonds are closely related to peaches and come from the rose family. Pistachios come from the cashew family, the same family as sumac and poison ivy! Chestnuts come from the beech family and are related to oaks. Hazelnuts come from the birch family and are related to hornbeam. And finally, walnuts and hickories are both a part of the walnut family. Even ginkgo and pines are considered a nut tree in many parts of the world!
While the nut tree category is relatively diverse, many species are not cold hardy in Iowa. The most commonly grown nut trees commercially here are walnut (Juglans spp.), hickories/pecans (Carya spp.), chestnuts (Castanea spp.), and hazelnuts (Corylus spp.).
The Grove
The Nut Trees were established in 1982 in the far southwest corner of the cultivated 40 acres. Several hybrid and cultivar introductions by the late Archie Sparks, the late Al Ferguson, and Ward Mally exist in this planting. Their involvement in the Iowa Nut Growers Association and Northern Nut Growers Association gave them great access to the best nut tree genetics at the time. Particular favorites of theirs to propagate were black walnut (Juglans nigra), shagbark hickory (Carya ovata), northern pecan (Carya illinoinensis), and chestnut (Castanea). Their love of the state and exploring its untapped potential led to the creation of many nut tree selections named after local landmarks near where they discovered superior trees. Many of the trees are reproduced by grafting, and in some cases the graft union where bark texture changes can still be viewed on mature trees. Cultivars in this collection were selected for their large, edible fruits. Other selection features include ease of cracking and self-hulling. Now that the grove has reached maturity, further selection is being done for the potential for ornamental trees, with considerations like small nut size, fall color, and final tree size/shape all being considered.
Unique Specimens
While many of the tree specimens in this grove have been the favorites of many plant professionals and visitors, there are several notable trees growing. The first is a Japanese wingnut (Pterocarya rhoifolia). Planted in 1979, this tree hails from Japan where it is commonly used as an ornamental tree and for lumber. Belonging to the walnut family, this species does produce nuts that are paired with little wings. The nut is edible, but is very small making it difficult to shell. A fast grower, it makes a stunning shade tree with great horizontal architecture.
Another specimen worth noting is a little known Iowa State University introduction called Stark Northern Prize Persian Walnut (ISU71-E18). A selection of the Persian walnut (Juglans regia), it was selected in 1971 at the Ames Horticulture Station by Dr. Paul Domoto. Proving to be a cold hardy variety, it was quickly picked up and distributed by Stark Brothers Nursery for decades. Now a rare tree this far north, interest in cold hardy Persian walnuts has regrown with the hopes of one day creating additional selections for Iowa.
Back to Our Plants hompage
Plant List:
Carya cordiformis – Bitternut hickory
C. cordiformis x C. ovata (C. x laneyi)
Carya x laneyi ‘Vermace’ – Vermace Laney’s hickory
Carya illinoinensis – Northern pecan
Carya illinoinensis ‘Donnellson’ – Donnellson northern pecan
Carya illinoinesis ‘Gibson’ – Gibson northern pecan
Carya illinoinensis ‘Le Baeu’ – La Baeu northern pecan
Carya laciniosa ‘Kaufman’ – Kaufman shellbark hickory
Carya laciniosa ‘Ross’ – Ross shellbark hickory
Carya laciniosa ‘Selbhers’ – Selbhers shellbark hickory
C. laciniosa x C. ovata (C. x dunbarii)
Carya x dunbarii – Dunbar’s hickory
Carya ovata – Shagbark hickory
Carya ovata ‘Abundance’ – Abundance shagbark hickory
Carya ovata ‘Hopson’ – Hopson shagbark hickory
Carya ovata ‘Silvis 303’ – Silvis 303 shagbark hickory
C. ovata x C. illinoinensis
Carya ovata x illinoinensis ‘Henke’ – Henke hican
Carya texana – Black hickory
Carya tomentosa – Mockernut hickory
Castanea dentata – American chestnut
Castanea mollissima – Chinese chestnut
Corylus americana ‘Purpleleaf Bailey Select’ – Purpleleaf Bailey Select American hazelnut
Corylus avellana – Common hazel
Corylus colurna – Turkish filbert
Juglans cinerea ‘Herrick’ – Herrick butternut
Juglans nigra – Black Walnut
Juglans nigra ‘Cranz’ – Crans black walnut
Juglans nigra ‘Davidson’ – Davidson black walnut
Juglans nigra ‘Eldora’ – Eldora black walnut
Juglans nigra ‘Sparks #127’ – Sparks #127 black walnut
Juglans nigra ‘Sparks #128’ – Sparks #128 black walnut
Juglans nigra ‘Sparks #147’ – Sparks #147 black walnut
Juglans nigra x regia
Juglans nigra x regia – Hybrid walnut
Juglans regia ‘Stark Northern Prize’ – Stark Northern Prize Persian walnut
Juglans x quadrangulata (J. cinerea x J. regia)
Juglans x quadrangulata ‘White’s Hybrid’ – Whites Hybrid walnut
Pterocarya rhoifolia – Japanese wingnut