Juglans cinerea

Juglans cinerea is a deciduous tree reaching nearly 100 ft. in height. Its bark is grayish-brown, with smooth ridges. The pith of the stems is transversely partitioned into chambers which are dark chocolate brown. The leaves are compound with 11-17 leaflets that have long, pointed tips. Leaflets from the middle of the leaf are the largest. The flowers are in dense, drooping catkins (resembling cats' tails) which protrude from the buds in autumn and lengthen in the spring. The nut resembles a short cylinder (1.5-2.75 inches long) with 2 halves and 2 or 4 ridges running end to end along its rough surface. Both the nut and the husk remain closed at maturity. Seed production begins when the tree has reached 20 years of age and peaks when it is 30-60 years old. Seeds are produced every year, but larger seed crops occur every 2-3 years. Germination of seeds usually takes place in the spring from seeds that fell the previous season. (Gleason and Cronquist 1991, Ostry et al. 1994).

There are some pubescence differences which will help to distinguish Butternut from the Black Walnut, even when the distinctive dark pith is not exposed. In J. cinerea, there is often a pad of dense small hairs extending transversely along the upper margin of the old leaf scars; in J. nigra, this pad is absent, although the circular area of bud pubescence is confusing, and some specimens are ambiguous. The underside of the leaflets in J. cinerea is +/- densely covered with mostly stellate hairs, while in J. nigra the pubescence is sparser and mostly of simple hairs. The pubescence of cinerea, including that on the fruit, is more clammy than that of J. nigra. Persons familiar with the species in the field will also know differences in fragrance of the foliage and fruit and in stain from the husks--all difficult to expresss in words (Voss, 1980).

Juglans cineara typically grows in rich mesophytic forests, lower slopes, ravines, and various types of bottomland, including banks and terraces of creeks and streams, and floodplain forests (Fernald 1950, Gleason and Cronquist 1991). This species achieves its best growth in well-drained bottomland and floodplain soils.

The following provides additional information on the specific habitats of J. cinerea in several states from different parts of the species' range:

The habitat in Ohio is mesic river terraces and ravines (Cusick 1992).

Michigan habitat includes streambanks, swamp forests, and upland beech-sugar maple, oak-hickory, and mixed hardwood stands (Voss 1985). In southern Michigan sites, associates may include such species as Ulmus americana (American elm), Acer saccharinum (silver maple), Fraxinus quadrangulata (blue ash), Betula alleghaniensis (yellow birch), Tilia americana (basswood), and many woodland and swamp herbs. In some areas, butternut occurs occasionally as a roadside tree.

The habitat in Illinois and Wisconsin is mesic and riparian hardwood forests, where associates of the overstory include Acer saccharum (sugar maple), Carpinus caroliniana (blue beech), Celtis occidentalis (hackberry), Fagus grandifolia (American beech), Prunus serotina (black cherry), Quercus alba (white oak), Quercus macrocarpa (bur oak), Quercus rubra (red oak), Tilia americana (basswood), and Ulmus americana (American elm). The herbaceous associates of this habitat include Claytonia virginiana (spring beauty), Dicentra cucullaria (squirrel corn), Hydrophyllum appendiculatum (appendaged waterleaf), Isopyrum biternatum (false meadow-rue), and Solidago caesia (woodland goldenrod). In wooded floodplain habitats, associate plant species include Celtis occidentalis, Cryptotaenia canadensis (honewort), Elymus virginicus (Virginia rye grass), Fraxinus pennsylvanica (red ash), Galium aparine (cleavers), Geum canadense (geum), Hydrophyllum virginianum (Virginia waterleaf), Laportea canadensis (wood nettle), Ranunculus septentrionalis (swamp buttercup), Toxicodendron radicans (poison ivy), Rudbeckia laciniata (cutleaf coneflower), Ulmus americana, and Viola sororia (woolly blue violet). A characteristic habitat in the Chicago region is springy, wooded, calcareous slopes, where limey water percolates through gravelly soils. Associate plant species in this habitat may include Angelica atropurpurea (angelica), Caltha palustris (marsh marigold), Cardamine bulbosa (spring cress), Fraxinus nigra (black ash), Lilium michiganense (Michigan lily), Mitella diphylla (bishop's cap), Ribes americanum (swamp gooseberry), Smilacina stellata (starry false solomon's seal), Solidago patula (swamp goldenrod), and Symplocarpus foetidus (skunk cabbage) (Swink and Wilhelm 1979).

The habitat in Indiana is mesic forests (Homoya 1992).

The typical habitat in Kentucky is mesic wooded ravines along streams, mesic limestone gorges, mesic deciduous forest, second growth in mixed hemlock forest, and upland mesic woods, occurring with Fraxinus americana (white ash), and several other species (KY HP 1992).

In Tennessee, Juglans cinerea occurs along creek bottoms in mesic forests and on lower slopes (TN ESD 1992).

In Mississippi, this species occurs on calcareous bluffs, along river and stream drainages, in mesophytic forests, and calcareous ravines. Populations are often found on north-facing slopes. Associate plant species include Acer spp. (maple), Carya spp. (hickory), Juglans nigra (black walnut), Liriodendron tulipifera (tuliptree), and Quercus macrocarpa (bur oak) (MS NHP 1992).

Habitat in Delaware consists of northwest-facing slopes of pastures, banks of streams running through meadows, and floodplain woods with partial shade (DE NHP 1992).

In Massachusettes this species a generalist in terms of soil moisture (it's found along a continuum from river bottomlands to mesic forests to talus and dry balds) but it does not seem to be a generalist in terms of bedrock substrate-in MA it avoids acid, nutrient poor substrates and appears to be restricted to areas underlain by basalt, marble, or dolomite (M. Dow Cullina, pers. comm., 2006).

Juglans cinerea achieves optimal growth on well-drained soils of bottomlands and floodplains, but rarely occurs in pure stands. According to Rink (1990), this species grows best in riparian sites and well-drained soils, but is seldom found on dry, compact, or infertile soils. Rink also notes that butternut is found at much higher elevations (up to 4900 ft) in the Virginias than black walnut. Butternut is shade-intolerant, growing best in full sunlight. Young trees can tolerate some competition from the side, but will not withstand shade from above. This species needs to be in the canopy in order to survive. Reproduction is successful only in areas where shade does not inhibit its growth, such as stand openings or in fields (Skilling 1993, Ostry et al. 1994).

This species is being seriously impacted, if not devastated, by a canker fungus (Sirococcus clavigignenti-juglandacearum) that is spreading rapidly throughout its range, and few stands remain uninfected. The origin of the disease is unknown, although Fogelson and Campbell (1990) believe it may have been introduced about 40 years ago on the east coast of the United States. According to Anderson (1993), 40- year-old cankers have been observed in North Carolina. Long noted as suffering from a canker dieback (frequently called "butternut decline"), scientists from Wisconsin first identified the disease agent as a new species of Sirococcus in 1967, although tests of trees in North Carolina demonstrated its presence there in 1952. This disease has spread quickly (within 30 years) throughout butternut's range, infecting and killing trees in all locations. In the Great Lakes states, all sites examined by researchers had been infected with canker. The disease vectors are poorly known, but the canker is believed to be transmitted at least in part by raindrops splashing spores from infected trees onto healthy ones, and possibly via insects. If the spores become airborne, they are able to be dispersed over great distances. The spores are produced throughout the growing season and can survive when weather conditions are cool and skies are overcast. (Kuntz et al. 1979, Fogelson and Campbell 1990, Forest Service News 1992, Ostry et al. 1994).

Symptoms of the disease include the appearance of lens-shaped cankers on the trunk, limbs, twigs, and immature nut of the tree. In spring, an inky-black, thin fluid is exuded from the cankers. These cankers usually continue to grow in size and girdle the tree, eventually killing it by destroying the cambium. The girdling of the tree often causes a wilting of the leaves, especially noticeable in the crown (Fogelson and Campbell 1990). Trees with reduced vigor become susceptible to insects and secondary disease agents, particularly Melanconis juglandis (E. and E.) Graves, which causes branch dieback (Skilling 1993).

Butternut is an important source of mast for wildlife, especially in the northern part of its range, where black walnut (Juglans nigra) does not occur. Squirrels and other rodents are some of the consumers of the seeds. (Ostry et al. 1994).

Male and female flowers borne seperately on the same tree. Squirrels, rabbits and white tailed deer eat the nuts. Squirrels disperse them.