The driveway walnut tree

As a follow-up to yesterday’s post, I decided to shoot some pictures of the black walnut tree in question. It had rained off and on, but the sun came out while I was shooting, making everything glow and glisten. In processing, I tried switching to black-and-white and found I preferred that for almost all the photos, with the possible exception of the one above. Here’s a slideshow of the set, which requires Flash, meaning that if you’re on an iPhone or iPad, you won’t be able to watch it. However, this is best viewed on a large monitor — once it starts playing, click the four-arrows icon at bottom right to expand it to full-screen. (If you’re on dial-up, it’s probably easiest to browse the set, and if you’re reading this via email or in a feed reader, you’ll probably have to click through to view the slideshow.)

The photo with my hand in it shows what I believe is the scar from our long-ago Frisbee attack. Usually black walnuts that sustain damage to a terminal bud end up forking, but this one did not. A single bud became the new main stem.

Black walnut wood is prized by furniture makers, and the supply is relatively scarce because the trees grow slowly once they start to get big. As these photos and yesterday’s post suggest, however, they grow quite rapidly in their first few decades. My feeling is once they start bearing nuts, that takes so much out of them that they don’t have much energy left to channel into wood. Consider they remain leafless for roughly seven and half months of the year at our latitude, not leafing out until early June, and the very woody nuts are always plentiful — I don’t think pollination ever fails.

The yard of my parents’ house is dominated by black walnuts, which might not seem like a good thing given their legendary inhospitabilty toward certain other plants, which can’t tolerate the chemical juglone exuded by black walnut leaves, husks and roots. However, for birdwatchers like my mom, they’re ideal because they leaf out so late and lose their leaves so early. When migrating warblers move through the yard, she has no trouble spotting them.

As for the walnuts, they are a bit of an acquired taste and a lot of work to remove from the shells, requiring a sledgehammer and extensive use of a nutpick. The hulls — source of the ink my friend Alison is so fond of — are easy enough to remove, but you have to wear gloves. If you don’t, as we didn’t when we were kids, you tend to provoke comments like, “Hey Bonta! Did you’ns run out toilet paper?” Kids can be cruel. These days, we find it much easier just to buy a jar of pre-shelled black walnuts for a couple dollars from the local Amish whenever we need some, so the squirrels up here feed very well.

Gray squirrels are scatter hoarders, and it’s their burying of the walnuts all around the yards and meadow that’s responsible for most of the new trees — those few that get past the deer (or boys with Frisbees). In the book North American Tree Squirrels, mammalogist Michael J. Steele recounts some of the strategies gray squirrels use to keep other squirrels from discovering their walnuts, including digging a couple fake burial sites in a row before finally burying the walnut for real if other squirrels are watching. I also once watched a squirrel excavate a walnut that had been buried about a foot down, clean it all off, then dig another hole a yard away and re-bury it. I suspect it thought another squirrel had watched the initial bury.

The most amazing fact about this behavior to me is that the squirrels rely on memory alone to recover hundreds of nuts, even when they’re buried under an additional foot or more of snow and ice. Steele has calculated that a squirrel digging a black walnut out of the frozen ground on a bitter cold January day, then chiseling through the rock-hard shell, expends more energy than it gets back from eating the nut. Hence, I suppose, the frequent raids on the birdfeeder to make up the deficit.

Don’t forget to submit tree-related links to the Festival of the Trees monthly blog carnival (deadline: September 30). The next edition will be at europeantrees — and we are still looking for a host of the following (Nov. 1st) edition.