Comprehensive DescriptionRead full entry
General: Walnut family or Juglandaceae. A monoecious tree with large pinnately compound alternate leaves without stipules. There are two members of the Juglandaceae family 1) Carya or pecan and hickory and 2) Juglans or walnut. Juglans is derived from a Latin phrase Jovis glans meaning “the acorn of Jove” and microcarpa refers to the small size of its fruit (Stephens, H.A. 1969). Little walnut is a small to medium tree with single or multiple trunks and spreading low branches. The mature height depends on the environmental conditions grown under, but heights of 6 to 15 meters have been described. Leaves are alternately attached to the tree and pinnately compound with 17-23 narrowly linear, lanceolate curved leaflets. Leaves overall are 9 to 23 centimeters (cm.) long. The individual leaflets are 3 to 9 cm. long and 1 to 2.5 cm. wide. Flowers bloom in May and have separate male and female flowers. Male flowers or catkins are yellow green and attached to last years twigs. Female flowers are small, yellow green and are located on the ends of branches in small clusters which appear in spring with leaves on new growth. Fruit is displayed in October and may be single or 2 to 3 in a cluster. Fruit shape is globular with a 2.8 to 3.2 cm. diameter and a thin brown hairy husk. The mature bark is brown, deeply fissured with ridges flat topped and occasionally loose. The bark of young trees and branches is often silvery gray and smooth.
Distribution: For current distribution, please consult the Plant Profile page for this species on the PLANTS Web site. Little walnut is a native species that can be found in southwestern and central Kansas through western Oklahoma and Texas, New Mexico and Arizona and south into northern Mexico. In Oklahoma little walnut is most abundant in and around the Wichita Mountains, but is scattered throughout the western part of the state (Oklahoma Biological Survey, 1999).
Habitat: Little walnut grows in dry, rocky ravine banks and hillsides (Stephens, 1973). It would also commonly be found within the narrow riparian forests adjoining a river or creek bottom.