Shagbark Hickory is a large native slow-growing but long-lived deciduous tree growing 70 to 100+ feet tall and over 2-1/2 feet wide, with a straight trunk and a narrow oblong crown with ascending branches.
The bark is distinctive, at first smooth and gray then becoming dark gray and deeply furrowed into long wide plates, that remain attached in the middle but curve away from the trunk at each end - resulting in the shaggy appearance the tree is named for.
Twigs are brownish and stout with numerous lighter colored lenticels and with the 3-lobed leaf scar the Walnut family usually has, which is said to resemble a monkey face. Buds are brown and the terminal bud is very large and hairy with 8 to 10 small brown scales but the inner scales become quite large and colorful as the bud breaks and the leaves are forming.
Leaves are alternate, pinnately compound, 8 to 14 inches long, with with 5 (and rarely 3 OR 7) elliptical or ovate leaflets. Each leaflet is stalkless with a fine saw-tooth hairy margin and a pointed tip. The terminal leaflet will be larger than the laterals and leaves of young plants will be much larger than on older plants. The upper surface is yellow-green to green, no hair, while the underside is more pale with fine hair when young, weathering to just tufts in late summer. Fall color is golden-brown.
Flowers: The tree is monoecious, that is with separate male and female flowers. Male flowers are yellow-green in slender drooping catkins, 3 to 4 inches long, 3 from one stalk from the base of this years twig. The tiny flowers have a 3-lobe calyx and several stamens. Flower stalks and bracts are without hairs, but the anthers have fine hair. Female flowers are about 1/8 inch long, appearing on a short terminal spike at the tips of the same twig. They have a 4-ridged ovary and a pair of styles. Flowers cross pollinate by wind.
Seed: Fertile female flowers produce a 1-1/4 to 2-1/4 inch nearly round nut, flattened at the tip, covered by a very thick husk that matures to a dark-brown to blackish color. They appear singly or in groups of 2 or 3. The husk splits along 4 lines. Fruit matures in the Autumn and drops from the tree the same year. The nut inside is lightly flattened, angled, whitish to light brown, sweet and edible. Seeds are dispersed by animals. Trees must be around 40 years of age to produce a good crop. Cold stratification is needed for seed germination.
Habitat: The root system has a deep taproot and can sprout vigorously from stumps. It is generally found on upland slopes with moist well-drained soil. It is moderately shade tolerant. As it does not spread via the root system, there are no large stands of the tree.
Names: The genus name Carya is an old name for walnut in which family this tree resides. The species name, ovata, means egg shaped and refers to the husk of the nut. The author name for the plant classification - "Mill." is for Philip Miller, Scottish botanist (1691-1771) who was chief gardener at the Chelsea Physic Garden and wrote "The Gardener's Dictionary". His work on this species was furthered by ‘K. Koch’ - Karl Heinrich Emil Koch (1809-1879), German botanist, Professor of Botany, first professional horticultural officer in Germany, plant collector in and near Asia Minor.
Comparisons: The nearest comparison is the Bitternut Hickory, C. cordiformis, which has seeds with much thinner husks and smoother bark that does not shed.
Above: Shagbark Hickory has a straight trunk and an oblong crown with ascending branches. Fall color is a golden-brown. The bark separates into plates, the ends of which tend to curve away from the tree.
Below: 1st photo - Male flowers are yellow-green in slender drooping catkins, 3 to 4 inches long, 3 from one stalk from the base of this years twig. 2nd photo - Female flowers are about 1/8 inch long, appearing on a short terminal spike at the tips of the same new twig as the male flowers. They have a 4-ridged ovary and a pair of styles. 3rd photo - Twigs have many lenticels, the shield-like Walnut family leaf scar and a very large terminal bud.
Below: 1st photo - Note the placement of the male catkins at the base of the newly forming twig. 2nd photo- The inner scales of the bud become quite large and colorful as the bud breaks and the leaves are forming.
Below: The compound leaf usually have 5 leaflets with sawtooth margins. The terminal leaflet is the largest.
Above and Below: The nut is covered by a very thick husk that matures to a dark-brown to blackish color (2nd photo above). The husk splits along 4 lines. The nut inside is lightly flattened, angled, whitish to light brown.
Notes: Shagbark Hickory is not indigenous to the Garden. Eloise Butler first planted it on April 29, 1911 with 4 young plants from Strands Nursery in Taylor's Falls, MN. Garden Curator Susan Wilkins added additional plants in 2008 and 2010. The tree is found in North America in the eastern half, from the central plains on the west then east to the coast, except Florida, in the US and in Canada it is known in Ontario, Quebec and P E Island. Within Minnesota, it is found in only 7 counties, all in the SE tip of the state. This is much less prevalent than the Bitternut Hickory, C. cordiformis. C. cordiformis and C. ovata are the only two species of Carya native to Minnesota.
Uses: Shagbark Hickory wood is hard, tough and resilient. The inner heartwood is close grained and was long used to make wooden wheels and spokes. It currently is used in furniture, flooring, tool handles and sporting goods. It imparts a hickory taste to foods when smoked with this wood. The nuts are highly prized by wildlife.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"