Castanea dentata

American chestnut

Fagaceae

The Basics

Taxonomy: Kingdom - Plantae (plants). Subkingdom - Viridiplantae (Green plants). Superdivision - embryophyta. Division - Tracheophyta (Vascular plants). Class - Magnoliopsida (dicotyledons). Order - Fagales. Family - Fagaceae. Genus - Castanea Mill. Species - Castanea dentata (Marsh.) Borkh.

Habitat: American chestnut was once a widespread and dominant species throughout the deciduous forests of eastern North America. American chestnut had the fastest growth and highest abundance in Braun's oak-chestnut forest region, but the species inhabited nearly all States east of the Mississippi River. American chestnut grew straight and tall, reaching up to 1.5 m in diameter and 37 m in height, and the species could live for several hundred years. The introduction of exotic pathogens, primarily the chestnut blight fungus, led to the extirpation of the species as a forest canopy dominant throughout its native range.

The shade tolerance of American chestnut is still under debate. Early observations suggest that American chestnut is relatively intolerant to moderately tolerant of shade. Recent studies have classified American chestnut as either shade tolerant or intermediately shade tolerant... Paillet found that chestnut can survive in deep shade under the canopy for up to three decades and is more shade tolerant than co-occurring sub-canopy species. When growing in a light-limited environment, American chestnut increases its specific leaf area and develops canopy architecture that is optimal for harvesting light.

It was among the most versatile trees on the continent, historically used for construction lumber, shingles, fence posts and rails, poles, paneling, trim, furniture, and firewood...The flavorful nut it produces was enjoyed raw, roasted, or boiled by Native Americans and settlers, and it was an important food source for livestock and wildlife such as turkeys and squirrels...American chestnut was once the major source of tannins for leather production in the United States. With tannin content of 6 to 11 percent and numerous large logs available, American chestnut was an obvious choice for the tanning industry.

Identification

Trees , often massive, formerly to 30 m, now persisting mostly as multistemmed resprouts to 5-10 m because of widespread destruction by blight. Bark gray, smooth when young, furrowed in age. Twigs glabrous. Leaves: petiole (8-)10-30(-40) mm. Leaf blade narrowly obovate to oblanceolate, 90-300 × 30-100 mm, base cuneate, margins sharply serrate, each tooth triangular, gradually tapering to awn often more than 2 mm, apex acute or acuminate, surfaces abaxially often without stellate trichomes, appearing glabrous but with evenly distributed, minute, multicellular, embedded glands between veins and sparse, straight, simple trichomes concentrated on veins, stellate or tufted trichomes absent. Staminate flowers with conspicuous pistillodes, whitish or yellowish straight hairs in center of flower. Pistillate flowers 3 per cupule. Fruits: cupule 4-valved, enclosing 3 flowers/fruits, valves irregularly dehiscing along 4 sutures at maturity, spines of cupule essentially glabrous, with a few scattered simple trichomes; nuts 3 per cupule, obovate, 18-25 × 18-25 mm, flattened on 1 or both sides, beak to 8mm excluding styles.

Threats

Pathogens: American chestnut might be the most susceptible tree in the Eastern United States to damaging agents. The most widespread damaging agent to American chestnut is the chestnut blight. The fungus was originally believed to be a new species and was named Diaportha parasitica, but it was discovered that it likely came into the United States on imported Asian Castanea species. The fungus was renamed Endothia parasitica, and then Cryphonectria parasitica, and it is most commonly referred to as the chestnut blight fungus.After 1930, most populations of Castanea dentata were nearly destroyed by the chestnut blight, caused by the introduced fungus Cryphonectria parasitica (Murrill) M. E. Barr. Virtually all known natural populations remain infected with the blight, and various studies continue in an effort to find ways to improve growth and vitality of infected trees. The species was widely planted outside of its native range (e.g., Illinois, Indiana, Iowa, Michigan, and Wisconsin), and some of these plantings remain blight-free because of their isolation. One particularly large grove was planted near West Salem, Wisconsin, in 1880, and continuing regeneration through seedlings has been documented (F. L. Paillet and P. A. Rutter 1989). Unfortunately, chestnut blight has recently been discovered in this isolated population and probably is extending to other isolated plantings in the west. As part of the effort to introduce blight-resistant strains of the American chestnut, breeding programs have produced hybrids of Castanea dentata in various combinations with exotic species of chestnut. Root rot caused by Phytophthora cinnamomi also contributed to the demise of Castanea species growing in lowland or riparian areas. The effects of these exotic pests resulted in the current listing of American chestnut as a species of special concern in Maine and Tennessee and as an endangered species in Kentucky and Michigan.

Fire: Damage to American chestnut bark may increase susceptibility to disease and insect infestation. However, the vigorous sprouting of American chestnut suggests that it may be able to persist following infrequent burning. Paillet noted evidence of fire preceding sharp increases in the proportion of American chestnut pollen in sediment... Excessive heating of the soil can injure chestnut when young, and sprouts are sensitive to frost when green, tender, and close to the ground.

Reproduction

Flowering and Fruiting - American chestnuts are monoecious, with male and female reproductive parts on the same tree. Flowers are staminate catkins that are borne on a central axis 5 to 10 inches long and are produced in clusters from the axils of leaves. Flowers appear from late May to June, after frosts have passed... The fruit of American chestnut, maturing between September and October, is a brown edible nut with a sweet taste. and the species was sometimes referred to as sweet chestnut due to its flavorful nut. The nut develops within a round prickly green bur that produces two to three nuts in each bur.

Seedling Establishment - Natural regeneration from seeds was probably rare in pre-blight years. The nuts were damaged by insects and highly utilized as a wildlife food source. Small seedlings were easily killed by fire or frosts.

Vegetative Regeneration - American chestnut is a tenacious sprouter, and its ability to repeatedly produce large numbers of fast-growing sprouts following dieback is largely responsible for its persistence in forests today. Coppice trees grow faster than trees regenerated from seed during the first 20 years. Because of their fast initial growth, sprouts reach their maximum average height growth rate during the first decade of growth.

Human uses

The American chestnut was one of the most important dominant forest trees of eastern North America prior to 1930. The nuts, sweet and edible, were a favorite confection in the eastern United States. The wood is light, strong, and resistant to decay; it was widely used for construction, furniture, and decorative trim. The bark was used for tanning leather. Native Americans used various parts of the plants of Castanea dentata medicinally as a cough syrup and to treat whooping cough, for heart trouble, and as a powder for chafed skin (D. E. Moerman 1986).

Species Distribution

Citation

USDA Plants Database
USDA, NRCS. 2016. The PLANTS Database. National Plant Data Team, Greensboro, NC 27401-4901 USA.

USFS Plant Database
Habeck, R. J. 1992. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory.

Flora of North America
Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico. 19+ vols. New York and Oxford.