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| ## Little Walnut {#little-walnut .Title-Header}                       |
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| *Juglans microcarpa* Berl.                                            |
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| Plant Symbol = JUMI                                                   |
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Contributed by: USDA NRCS Kansas Plant Materials Center, Manhattan,
Kansas

![](media/image2.jpeg){width="3.4375in" height="2.2916666666666665in"}

Fruit and foliage of little walnut photographed by W.L. Wagner @
USDA-NRCS Plants Database.

##### Alternate Names  {#alternate-names .Header-3}

##### Texas walnut, dwarf walnut, river walnut, nogal, Texas black walnut {#texas-walnut-dwarf-walnut-river-walnut-nogal-texas-black-walnut .Header-3}

##### Uses {#uses .Header-3}

The wood of little walnut is sometimes used in the production of
furniture, cabinets, paneling, and veneer, but its scarcity limits its
use in this regard. The nuts produced by this tree are consumed by
wildlife and are considered a valuable food source for many small
mammals. Deer are also reported to browse little walnut. Little walnut
shows promise as a small tree for shelterbelt and conservation tree
plantings especially in dry climates. Little walnut has been used as
rootstock in developing non-native walnuts and has potential value in
the development of walnut cultivars. Plants were first cultivated in
1868 (Brinkman, 1974).

##### Status {#status .Header-3}

Please consult the PLANTS Web site and your State Department of Natural
Resources for this plant's current status (e.g. threatened or endangered
species, state noxious status, and wetland indicator values).

#####  {#section .Header-3}

##### Description {#description .Header-3}

*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.

##### Adaptation {#adaptation .Header-3}

This tree is adapted to sites that are more severely limited, moisture
wise than other trees. Accessions that are being grown in Tribune, KS
have responded well to the low water potential that they have
experienced in that western region of Kansas. Little walnut commonly
grows on shallow calcareous or alluvial soils.

##### Establishment {#establishment .Header-3}

Propagation by seed is the most reliable way to produce little walnut
seedlings. Like most walnut species, the seeds are characterized as
having a dormant embryo (Brinkman, 1974). The North American species
also have a hard seed coat (Young and Young, 1992). Dormancy can be
broken by chilling at 3 to 5 degrees Centigrade (°C) for 90 to 120 days.
In the nursery trade walnuts are either sown in the fall shortly after
harvest or pre-chilled outdoors over winter in moist sand, covered with
60 cm of soil mulch. Screening is used to prevent rodent damage and
normally fungicide is applied to prevent disease during the long
pre-chilling process. After pre-chilling is accomplished a germination
test can be conducted in moist sand at 20 to 30 °C alternating
temperatures. The removal of a small section of shell may speed up the
germination at this point. A germination percentage of around 50 percent
is normal. Pre-chilled seed can be sown in the spring. Some nurseries
simply broadcast the nuts on a tilled surface and then press the nuts
into the ground with a roller. Some nursery personnel hand sows the nuts
at a rate of 160 per meter squared. Seed should be covered with 2.5 to
5.0 cm. of nursery soil and again protected from rodent damage. Cleaned
seed averages 203 seed units in a kilogram (Brinkman, 1974).

##### Management {#management .Header-3}

##### Seedlings will need to be protected from browsing animals until established. Seedling growth rate will be fairly rapid once the plants are established and growing well. Little walnut will bear fruit at approximately 15 to 20 years. The interval (2 to 3 years) and amount of fruit produced will be irregular in subsequent years (Young and Young, 1992). The nut meat of little walnut is described as nutritious and of high quality (Simpson, 1988).  {#seedlings-will-need-to-be-protected-from-browsing-animals-until-established.-seedling-growth-rate-will-be-fairly-rapid-once-the-plants-are-established-and-growing-well.-little-walnut-will-bear-fruit-at-approximately-15-to-20-years.-the-interval-2-to-3-years-and-amount-of-fruit-produced-will-be-irregular-in-subsequent-years-young-and-young-1992.-the-nut-meat-of-little-walnut-is-described-as-nutritious-and-of-high-quality-simpson-1988. .Header-3}

#####  {#section-1 .Header-3}

##### Pests and Potential Problems {#pests-and-potential-problems .Header-3}

The walnut husk fly infests ripening fruit of little walnut after summer
rains (Lamb, 1971). The amount of damage caused by this insect is
variable, but appears to be less in open, windy areas. Little walnut is
highly susceptible to root or crown rot when periodically flooded. It is
less susceptible to the fungus that causes walnut anthracnose than is
black walnut.

**Environmental Concerns**

There are no known environmental concerns associated with little walnut.

##### Seeds and Plant Production {#seeds-and-plant-production .Header-3}

##### Walnut fruits should be collected from the ground in the fall or early winter, either after naturally falling from the trees or being knocked from the trees by flailing or shaking. Mechanical tree shakers are used in the commercial production of walnuts. Nuts are easiest to extract from husks at the early stages when husks are softening. At later stages husks become mushy and can not be removed completely and if allowed to dry completely the husks become very hard and removal is all but impossible. After cleaning, unfilled nuts can be separated from filled nuts by floating them in water. Seed enclosed in a husk will germinate, but for standardization in planting and in topical applications of fungicides husks are generally removed in nursery operations.  {#walnut-fruits-should-be-collected-from-the-ground-in-the-fall-or-early-winter-either-after-naturally-falling-from-the-trees-or-being-knocked-from-the-trees-by-flailing-or-shaking.-mechanical-tree-shakers-are-used-in-the-commercial-production-of-walnuts.-nuts-are-easiest-to-extract-from-husks-at-the-early-stages-when-husks-are-softening.-at-later-stages-husks-become-mushy-and-can-not-be-removed-completely-and-if-allowed-to-dry-completely-the-husks-become-very-hard-and-removal-is-all-but-impossible.-after-cleaning-unfilled-nuts-can-be-separated-from-filled-nuts-by-floating-them-in-water.-seed-enclosed-in-a-husk-will-germinate-but-for-standardization-in-planting-and-in-topical-applications-of-fungicides-husks-are-generally-removed-in-nursery-operations. .Header-3}

##### Seeds of *Juglans* can be stored for long periods of time at low temperatures (3 to 4 °C) and high (80 to 90 %) humidity (Young and Young, 1992). Most species of this genus have a dormant embryo and must be stratified 3 to 4 months or planted in the fall to break the dormancy (Dirr and Heuser, 1987). {#seeds-of-juglans-can-be-stored-for-long-periods-of-time-at-low-temperatures-3-to-4-c-and-high-80-to-90-humidity-young-and-young-1992.-most-species-of-this-genus-have-a-dormant-embryo-and-must-be-stratified-3-to-4-months-or-planted-in-the-fall-to-break-the-dormancy-dirr-and-heuser-1987. .Header-3}

#####  {#section-2 .Header-3}

##### Cultivars, Improved, and Selected Materials (and area of origin) {#cultivars-improved-and-selected-materials-and-area-of-origin .Header-3}

Contact your local Natural Resources Conservation Service (formerly Soil
Conservation Service) office for more information. Look in the phone
book under "United States Government." The Natural Resources
Conservation Service will be listed under the subheading "Department of
Agriculture." There are currently no conservation releases of little
walnut from the plant materials program. However, they are commercially
available at selected nurseries.

##### References {#references .Header-3}

##### Brinkman, K.A. 1974. Juglans L. Walnut. In: Schopmeyer, C.S., Ed. Seeds of woody plants in the United States. USDA Forest Service Agric. Handb. No. 450. Washington, D.C. {#brinkman-k.a.-1974.-juglans-l.-walnut.-in-schopmeyer-c.s.-ed.-seeds-of-woody-plants-in-the-united-states.-usda-forest-service-agric.-handb.-no.-450.-washington-d.c. .Header-3}

#####  {#section-3 .Header-3}

##### Dirr, M.A. and C.W. Heuser. 1987. The reference manual of woody plant propagation. Varsity Press Inc., Athens, GA. {#dirr-m.a.-and-c.w.-heuser.-1987.-the-reference-manual-of-woody-plant-propagation.-varsity-press-inc.-athens-ga. .Header-3}

#####  {#section-4 .Header-3}

##### Lamb, S.H. 1971. Woody plants of New Mexico and their value to wildlife. Bulletin 14. New Mexico Department of Game and Fish, Albuquerque, NM.  {#lamb-s.h.-1971.-woody-plants-of-new-mexico-and-their-value-to-wildlife.-bulletin-14.-new-mexico-department-of-game-and-fish-albuquerque-nm. .Header-3}

#####  {#section-5 .Header-3}

##### Oklahoma Biological Survey. 1999. *Juglans microcarpa* Berl. var. *microcarpa.* (http://www.biosurvey.ou.edu/shrub/jumim.htm) \[online: cited 15 October 2008\]. University of Oklahoma, Norman, OK. {#oklahoma-biological-survey.-1999.-juglans-microcarpa-berl.-var.-microcarpa.-httpwww.biosurvey.ou.edushrubjumim.htm-online-cited-15-october-2008.-university-of-oklahoma-norman-ok. .Header-3}

#####  {#section-6 .Header-3}

##### Simpson, B.J. 1988. A field guide to Texas trees. Texas Monthly Press. Austin, TX. {#simpson-b.j.-1988.-a-field-guide-to-texas-trees.-texas-monthly-press.-austin-tx. .Header-3}

#####  {#section-7 .Header-3}

##### Stephens, H.A. 1969. Trees, shrubs, and woody vines of Kansas. University Press of Kansas. Lawrence, KS. {#stephens-h.a.-1969.-trees-shrubs-and-woody-vines-of-kansas.-university-press-of-kansas.-lawrence-ks. .Header-3}

#####  {#section-8 .Header-3}

##### Stephens, H.A. 1973. Woody plants of the North Central Plains. University of Kansas Press. Lawrence, KS. {#stephens-h.a.-1973.-woody-plants-of-the-north-central-plains.-university-of-kansas-press.-lawrence-ks. .Header-3}

#####  {#section-9 .Header-3}

USDA, NRCS. 2008. The PLANTS database
([http://plants.usda.gov](http://plants.usda.gov/), 20 October 2008).
National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

##### Young, J.A. and C.G. Young. 1992. Seeds of woody plants in North America. Dioscorides Press. Portland,OR. {#young-j.a.-and-c.g.-young.-1992.-seeds-of-woody-plants-in-north-america.-dioscorides-press.-portlandor. .Header-3}

#####  {#section-10 .Header-3}

##### Prepared By {#prepared-by .Header-3}

##### *Richard L. Wynia*, USDA NRCS Plant Materials Center, Manhattan, Kansas  {#richard-l.-wynia-usda-nrcs-plant-materials-center-manhattan-kansas .Header-3}

##### Species Coordinator  {#species-coordinator .Header-3}

##### *Morris J. Houck,* USDANRCS Louisiana State Office, Alexandria, Louisiana  {#morris-j.-houck-usdanrcs-louisiana-state-office-alexandria-louisiana .Header-3}

##### Edited: 081029 jsp {#edited-081029-jsp .Header-4}

For more information about this and other plants, please contact your
local NRCS field office or Conservation District, and visit the PLANTS
Web site\<[http://plants.usda.gov](http://plants.usda.gov/)\> or the
Plant Materials Program Web site
\<[http://Plant-Materials.nrcs.usda.gov](http://Plant-Materials.nrcs.usda.gov/)\>

*The U.S. Department of Agriculture (USDA) prohibits discrimination in
all its programs and activities on the basis of race, color, national
origin, sex, religion, age, disability, political beliefs, sexual
orientation, and marital or family status. (Not all prohibited bases
apply to all programs.) Persons with disabilities who require
alternative means for communication of program information (Braille,
large print, audiotape, etc.) should contact USDA\'s [TARGET
Center](http://www.usda.gov/oo/target.htm) at 202-720-2600 (voice and
TDD).*

*To file a complaint of discrimination write USDA, Director, Office of
Civil Rights, Room 326-W, Whitten Building, 14th and Independence
Avenue, SW, Washington, DC 20250-9410 or call 202-720-5964 (voice or
TDD). USDA is an equal opportunity provider and employer.*

Read about [*Civil Rights at the Natural Resources Conservation
Service*](http://www.nrcs.usda.gov/about/civilrights/).

#####  {#section-11 .Header-3}