A Decent Nobody, with Warts

A few months ago a friend who also has hackberry trees in her yard asked me if the leaves on our hackberry trees develop “warts” too. They do, indeed. I have been meaning to investigate this situation and on a recent visit to the Kansas City public library came across The Urban Tree Guide: An Uncommon Field Guide for City and Town by Arthur Plotnik, a Chicago author widely known for a book titled The Elements of Editing after Strunk and White’s The Elements of Style. Plotnik has also published a book, rather waggishly titled Spunk and Bite, which is a guide to lively writing. I haven’t had the pleasure to read that, yet, but if Plotnik’s tree guide is any indication, Spunk and Bite should be a lot of fun. He also maintains a blog (which he refers to as a “snog”) named The Lubricated Snoot. The illustrations in his tree guide are provided by Plotnik’s wife, Chicago artist and teacher Mary Phelan.


As the title suggests, the book concentrates on trees one might find in urban areas, covering more than 200 species. In addition to helpful identification tips, latin names, common names, and other such info, each entry includes a detailed essay relating interesting information, a sort of character dossier, about each tree.

But I was uninspired by tree-identification field guides. Most lacked heartfelt descriptions and none focused on trees in the city. They offered brief descriptive data — leaf and twig morphology (form, measurements), sub varieties, and zonal habitat. Enough to guide field trippers, perhaps, but not to reveal a tree’s personality. (p. 5)

Plotnik’s hackberry entry is titled “A Decent Nobody, with Warts.” The Latin for common hackberry (what I believe we have in our yard and shown in the first image included with this post) is Family: Ulmaceae (Elm); Genus: Celtis (hackberry); Celtis occidentalis (Common Hackberry).

Hackberry leaves often host eraser-size “nipple galls,” the dwellings of minute jumping lice. Located on the underside of the leaf, the hard and well-sealed galls take on amusing shapes, like cartoon fireplugs or baby bottle nipples.

Naming them lice sounds pretty scary, I have to say. We see swarms of these critters in the spring and fall. I previously thought they were miniature leaf-hoppers. Plotnik has done his homework, though. Lice, indeed. In fact, jumping plant lice or hackberry psyllids, described in detail on this Ohio State University fact sheet. Elly and I don’t spray insecticides to control them (perish the thought!) and simply put up with the nuisance in the spring and fall, periodically vacuuming them up from door and window sills with my shop vac. Here is a close-up image of one of the nipple galls I found on a hackberry leaf lying in our yard. Each gall includes a single psyllid. The adult insect is tiny, about 1/8-inch in length, and is said to resemble a miniature cicada. I’ll have to use a hand lens on one to see if I agree with that description.


Here are hackberries on the tree. A number of the galls can also be seen. The tree leaves look quite eaten up, diseased even. This is natural and does not indicate any problem with the health of the tree. In fact, a book I was reading about organic landscaping recently (don’t have the title too hand, my apologizes) stated that using ornamental plants which are “naturally resistant” to insect damage actually harms local biospheres by reducing insect populations which are critical to birds and other wildlife. This is one of the big objections to non-native plants, which are often introduced for the very reason which makes them harmful: the fact that native insects have evolved to eat native plants. This hadn’t occurred to me, but it makes total sense.


Mature hackberry trees have a sort of weird, warty bark (consistent with the warty leaves, though, in no way related to the pysllids). Here is a closeup of the bark on one of ours.


And, finally, an image of Elly and myself, taken last Sunday. We spent most of the day in our backyard. The weather was delightful. Elly proofed galleys for the Nelson-Atkins Museum’s new handbook (managing one of the coolest museum stores in the country isn’t enough of a challenge by itself, apparently), and I spent my time reading and photographing our hackberry trees...