Wednesday, October 17, 2012

Black Walnut

A cluster of 2 Black Walnuts
This weekend’s high winds knocked many of the Black Walnut (Juglans nigra) out of the trees and prompted me scurry around like a squirrel and stash a bunch of nuts for the winter. Continuing in the vein of last month’s posts on Manchurian Walnut (Juglans mandshurica) and Japanese Walnut (Juglans ailantifolia var. cordiformis), I thought I would start with a detailed description of the species.

Deep braided fissures of Black Walnut bark
Notice the fine hairs in the vein axils
Black Walnuts are the largest of 6 species of walnut that are native to North America, often reaching 130 feet tall. They are frequently planted outside of their native central and eastern US range, and it not uncommon to find them scattered throughout our region, especially east of the Cascades next to farmhouses, and in parks and yards. Black Walnuts have brownish grey bark with braided fissures. Twigs are also brownish grey with sporadic small lenticels and heart shaped leaf scars. The pinnately compound leaves are 8 to 24 inches long with slightly hairy petioles, especially near the base. Each leaf usually has 15 to 19 lanceolate leaflets that range from 2-6 inches long and roughly ¼ as wide. The terminal leaflet is very small and sometimes absent. Leaflets are often slightly curved and have serrated margins; the upper surfaces are smooth except for small scattered hairs on the veins, and lower leaf surfaces are minutely hairy, but more conspicuously so at the axils of the leaf veins. Fruits are spherical, 1.5-3 inches wide, and are typically found in clusters of 1 or 2 but sometimes in groups of 3. 

According to the US Forest Service Silvics Manual, Black Walnuts do not produce heavily until they are over 20 to 30 years old, at which point you can anticipate good nut crops 2 out of every 5 years. They fall in September and October about the same time as leaf drop, and I think they look like small green tennis balls before their hulls blacken and shrivel.

Several bags worth of walnuts in a pile
I have never been able to collect Black Walnuts in very large quantities, but this year I found an irresistible tree only 3 blocks away from my house that had dropped a thick layer of walnuts all over the street and sidewalk. I grabbed a large paper bag and my camera and headed down the street to pick. 5 minutes later, my bag was full! I dumped it out in a pile and filled it up again… and again… and again. In just a few hours, I could have easily filled my pickup truck with walnuts from just one tree if I had permission from all the adjacent landowners and if all the walnuts were on the ground.

The husks break off easily when you stomp on them.
Already having more than a year’s supply, I stopped collecting and started processing. I spread the walnuts out on the concrete and stomped on them to break open their green husks and reveal their fissured walnut shells. The husks are very resinous and quickly stained my hands, shoes, and anything else that touched them, an iodine color. I spread my Black Walnuts out on baking sheets to slowly dry in the shell. In a few months, I will crack them with a hammer and do a taste comparison with the other species of walnuts that I have been fortunate enough to collect this year.

After removing the husk I lay my walnuts on a baking sheet to dry
Husk, shell, and nutmeat comparison for 3 species of walnut

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