Walnut

(Juglans nigra)

Interesting Information About Plant:

    The Romans valued the walnut tree for wood which was used to make furniture and for the fruit.  Anglers during the time of the Romans used the leaves from this tree to bring worms to the surface and then used them for bait.  The fruit contains a nut-like inside that is very popular to eat and used in numerous desserts.  In the south of Europe the oil from the kernels is used by artists for mixing with delicate colors, for lamps, as a substitute for olive oil, and as a hair-wash.  At present time walnut wood is still highly valued.  Many of the everyday things we use are made from walnut.  The best logs are sliced for panelling or decorative veneer.  The wood is also used for high-quality furniture, cabinets, interior joinery, rifle butts and gunstocks, boats, musical instruments, clock cases, carvings, and many other novelty products.  The walnut tree produces a chemical that causes allelopathy.  Allelopathy discourages other plant growth around the walnut tree.

Common Name:  Walnut

Scientific Name:  Juglans nigra

Family Name (Scientific and Common):   Juglandaceae / Walnut Family

Continent of Origin: North America

Most Distinguishing Morphological Features of This Plant:  The most distinguishing feature of the walnut tree is the fleshy tree fruit that is produces with a nut-like center and the female reproductive organ called catkin.

Plant Growth Habit: Large Tree

Height at Maturity: More than 10 Feet

Life Span:  Perennial

Seasonal Habit: Deciduous Perennial

Growth Habitat: Full Sun

Manner of Culture: Native Species

Thorns on Younger Stem?: No

Cross Section of Younger Stem: Roundish

Stem (or Trunk) Diameter: More Than The Diameter of a Coffee-Mug 

Produces Brownish Bark?:   Yes

Bark Peeling in Many Areas?:  No

Characteristics of Mature (Brownish) Bark:  Bumpy

Type of Leaf:  Flat, Thin Leaf

Length of Leaf (or Leaflet):  Longer Than a Writing Pen

Leaf Complexity:  Pinnately Compound

Shape of Leaf:    Simple

Edge of Leaf?:   Serrated

Leaf Arrangement:  Alternate

Leaf has Petiole?:  Yes 

Patterns of Main-Veins:  Pinnate

Leaf Hairiness:  No Hairs

Color of Foliage in Summer:   Green

Change in Color of Foliage in October:   Changes to Yellow

Flowering Season:  Spring

Flowers:  in Loose Group

Type of Flower:  Catkin

Color of Flower:   Green

Shape of Individual Flower:  Other (Catkin)

Size of Individual Flower:  Between a Quarter and the Length of a Credit Card (Female) & Larger than the Length of a Credit Card (Male)

Sexuality:  Male and Female on Same Plant

Size of Fruit:  Between a Quarter and the Length of a Credit Card

Fruit Fleshiness at Maturity?:    Fleshy

Shape of Fruit:    Spherical

Color of Fruit at Maturity:  Green

Fruit Desirable to Birds or Squirrels?:  Yes

Unique Morphological Features of Plant: 

Is the Plant Poisonous:  None of Plant

Pesty Plant (weedy, hard to control)?:  Yes

Louisville Plants That Are Most Easily Confused With This One: Oak, Tree of Heaven (Leaves)

Page prepared by:

Cole Lambert

 November 2005