Sunday, November 28, 2021

Butternut Redux--A New Generation Bears its First Crop

This has been a breakthrough year for those of us working to bring back the native butternut--a species laid low by an introduced canker disease.. 

Twelve years after I helped Bill Sachs collect one of the last known harvests of native butternuts in Princeton, the new generation has finally born a crop of its own. Butternuts, also called white walnuts, or Juglans cinerea, bear nuts similar in look to black walnuts, but are oval rather than round. 

Bill continued to harvest and plant butternuts from the TRI property for a couple more years, but that pair of trees was then lost, with one blown down and the other cut down, ironically as part of an environmental remediation of contaminated soil. Most of the other known specimens, solitary so unable to bear, at Herrontown Woods and Mountain Lakes, have since been lost as well, lending all the more importance to this new generation of trees, grown by Bill and planted around town. 

We planted multiple trees, for cross pollination purposes, at Mountain Lakes, Herrontown Woods, Harrison Street Park, and at the TRI property where the seeds had originally come from. 

The saplings needed to be caged, to protect them from the deer. I made the mistake of removing a cage when a tree was tall enough that the deer could no longer reach the leaves. Bucks proceeded to rub the bark off the trunk, reducing a promising tree to root sprouts. A post from a couple years ago tells of some of the persistence required to nurse a new generation towards maturity. Along with deer, the young butternuts have been in danger of being smothered by fast-growing Japanese honeysuckle and grape vines, and trees like sweetgums and mulberries that rise quickly to fill the sunny openings the young butternuts need to grow.  Gardening, even wild gardening with native species, teaches the necessity of followup. 

This year, the butternuts had to deal not only with the 17 year cicadas' heavy pruning, but also the expanding presence of spotted lanternflies. 

Adding to the young trees' burden were some galls, which Bill said were most likely caused by walnut leaf gall mites

But despite all of that, the long awaited flowering of this new generation was spotted in July, and a few nuts collected in fall that appear to be viable, offering hope of yet another generation to come.

This fall's harvest is mostly being planted to grow more trees. Bill plants the butternut seed "in tall pots to be kept outdoors for the winter. This has worked well in the past."

Here are some additional tidbits gleaned from correspondence with Bill. The "float test" is used to determine whether a nut is viable. If it floats in water, it lacks a viable seed inside.

Dehusking walnuts and butternuts:
"I don’t really know if it’s absolutely necessary to dehusk walnuts or butternuts before a float test, though I think it is prudent. If you have a lot of nuts the best way to dehusk them is to use an old cement mixer with rocks and water… since I don’t have an old cement mixer, I use a piece of ½ inch plywood about 18 in by 6 in. I put a butternut or walnut in the driveway or street, put the plywood on top and use my foot with pressure to roll the nut under the plywood. (Use gloves to handle the nuts if you don’t want to stain your hands.) The husk comes off pretty easily. Then I put the largely dehusked nuts in a bucket of water and use a still wire brush to complete the cleaning."

Identifying butternuts: "Butternut bark is characteristically a lighter gray with broader ridges than black walnut (but not always). Easier to tell for sure from a twig with a terminal and a few lateral buds. If you slit the twig, butternut will have a dark chocolate-colored, chambered pith, and the leaf scars typically have a hairy fringe (or mustache) along the upper margin. When the leaves are still on the tree the leaf rachis will be tomentose or pubescent (hairy). Not sure if this carries over to fallen leaves on the ground in the winter. Finally, butternut trees often have poor form. In contrast, black walnut has a buff-pink chambered pith, no hairy fringes along the top edge of the leaf scars and the rachis is smooth (among other differences)."

Some additional reading recommended: 


  1. Steve, thanks for your informative article on butternuts. I have been interested in these wonders of nature for at least 50 years in Princeton, and have enjoyed many harvests. But as you say, they are not nearly as plentiful as black walnuts, and thanks for explaining their difficulties in surviving. I applaud the efforts you and your friends are making to revive this magnificent tree and source for humans, but of course, very few people understand such things.

    I'm hoping that some of the Asians populating the area will find value in our natural products and support them. I've already seen signs of it. They are from a different culture, and hopefully we can adopt the benefits they offer.

    I also volunteer that butternuts have important advantages over their black walnut cousins. Incidentally, the black walnut, Juglans nigra, the butternut, Juglans cinerea, and the so-called English walnut, which actually came from Iran, Juglans regia all have the same genus, supporting very well the tectonic plate theory, which postulates that at some time in the past all land masses were connected. The Carpathanian walnut is a variety of Juglans regia, able to grow in cooler climates.

    But anyway, I find the butternuts much more creamy or rich in tasting than the black walnut, and for me, who is a self described expert black walnut cracker, deftly using a hammer on a hard surface and my fingers, the butternut often allows you to extract the entire meat intact. This is not possible (for me) with the black walnut, and certainly impossible with most hickory nuts, even well dried ones. But cracking technique is very important, and not worth my getting into here.

    I would like to mention my two methods for removing the husks. In the first method, it's best to wait until the dropped nuts start decaying, with the husks turning black and squishy, containing maggots. Right there under the tree is a good time to remove the husk by stomping on it and rolling the nut under the soles and heels of your feet. The advantages here are that it's immediate, much less time consuming than a process of gathering and transporting, and it greatly reduces the amount of stuff you want to bag and carry to your car.

    Another method I use, particularly if the husks are not sufficiently rotted, is to collect them in a plastic garbage bag, tie it shut and leave it in a garage for the husks to rot. After a couple weeks, usually long enough for the maggots to die, put a batch of the nuts into a wheelbarrow and hit them with a rubber mallet, the kind you use to hammer on the hubcaps for your car. There's a recommended technique for hammering that you quickly get the hang of. I may have a slight preference for the first technique, but the advantage of this second one is that you needn't spend as much time stomping nuts under the tree - say if it's getting dark, or if you're wary about being thrown off the premises. But then you have a lot more weight to carry to your car. And then you have to wait weeks before you get what you want.

    After de-husking, I put them up in a garage loft to dry, which is very important, because drying shrinks the meats, allowing much easier extraction of whole pieces. It's nearly impossible to extract fresh meats with any of these nuts, especially hickory nuts even when the latter are well dried, with all their nooks and crannies.

    Tom Tonon

    1. Great information, Tom. Thank you! If you know of any native butternut trees bearing in Princeton, that could be helpful for our propagation initiative, in order to smuggle more genetic diversity into the future.

  2. Steve, I'll contact you by email.