Foraging: Identifying & Harvesting Black Locust

Identification difficulty: Beginner

When I got formally into "foraging" as an adult, and read about the black locust, it came as a pleasant surprise to learn that this tree and I were already well acquainted. As a very young child, our next-door neighbor had on of these at the side of his house, and I was fixated. I called it the "Tutti Fruity Tree", mainly because its autumn foliage was primarily shades of pink and coral, rather than the more typical red, gold and orange. I loved that tree from late spring (where I would shower myself in the fallen blossoms) through the fall, when it's unusual coloration captivated me. I had even "foraged" as a 5-year old for the fallen bean pods; that is to say, I gathered them up and made mud-pies. I had no idea that the flowers were edible, nor would my parents have allowed me to really eat them, even if I had wanted to.

The black locust (Robinia pseudoacacia, also called the false Acacia) is a somewhat ugly tree, 50 weeks out of the year. It has contorted grey bark, deeply contoured, and it doesn't always grow straight. The canopy is nice enough, but the strange leaves don't provide much shade. But in late-spring, when it blooms it fills the air with an enticing aroma; walking under it is like entering a dryad's cathedral, and the fallen petals cover the ground with white.

The blooms of the black locust tree are only available for a very short while (2 weeks or so), in late spring. In the Northeast, this happens somewhere between mid-May and mid-June, the exact times may vary depending on temperature. I never remember seeing them in CT (though they grow there), but of course I remember them from my early childhood in NY; and in NJ they seem to be everywhere--transforming a drive along rt. 80 west or the parkway into a fairyland.

All 15 of these small "leaflets"
together form one leaf.

Identification
Black locust trees are among the easiest to identify. They have dark grey, convoluted bark, with deep grooves and ridges. From a distance, the bark somewhat resembles that of a shagbark hickory, but up close it isn't actually pealing away. Both the leaves and the flowers look surprisingly exotic for a plant whose origins are in the Appalachian mountains.

The leaves are "oddly pinnately compound", which is to say each leaf is made up of multiple "leaflets" which grow opposite each other, except for the "odd" leaf, who sticks out at the top. Here is a great graphic for explaining compound leaves. If you look at the leaf image I posted to the left, I used to assume that each of those small leaves are the leaves--but in actuality all 15 of them together form the leaf. Each black locust leaf will have 11-21 leaflets.

The branches are slender and become bowed when the tree is blooming

The flowers are just so exotic looking

The flowers resemble pea flowers, but dangle in clusters, like grapes. Each is a creamy white color, with a pinkish base, and a small yellow area inside. The branches are slender, and seem almost incapable of supporting the flowers--they become bowed down with the weight, and whip about in the wind.

Black locust's original range was apparently rather limited, somewhere in the southern Appalachian and thge Ozark mountains, however it has spread to most of the eastern seaboard and throughout the mid-west.

Black locust bark

There are other locust trees, including the Bristly locust, with pink flowers, and the New Mexican locust, whose flowers are pink (but sometimes pale pink, seeming similar). Apparently those flowers are also edible, but I have never tried them. According to Thayer, Steve Brill says that "There are no similar trees in North America with poisonous flowers". Just to be on the safe side, you may want to sample pink flowers (which could belong to the clammy locus (edibility unknown) in small amounts.)

The honey locust (whose flowers look very different) apparently produces edible seed pods. I don't live in an area where they grow, so I cannot attest to this. The honey locust has thorns growing from the bark.

Harvesting & Use
For the black locust, the flowers are the edible portion. Thayer also says the seeds are edible, but I have seen conflicting evidence and haven't tried them. The seed pods are poisonous. The bark and leaves are listed as toxic, so make sure to weed out any leaves that get into your harvest. The flowers strip away easily, right into your bag. The entire flower portion is edible, with the pink base having the sweetest flavor. Once harvested, leave the bag open to allow the spiders you will invariably have captured to escape. Avoid harvesting blossoms from the lowest dangling branches, as they sometimes pick up grit when they blow against the ground.

Black locust flowers taste surprisingly like the sweetest of sweet spring peas, but with a floral element as well. The texture of the bases is somewhat crunchy, like celery, but without any stringiness. They are a great snack to nibble on (after you have inspected them for bugs), and they are wonderful in salads. Check out my black locust pinterest board for recipes from all over the internet.

Sustainablity
We don't usually use the word "invasive" for trees, but apparently black locust is considered to be an invasive weed in Australia. It certainly grows like a weed, seeming to prefer disturbed ground, around highways, rivers, and ponds. When you take a flower, you don't actually hurt a plant, you simply prevent that flower from becoming a seed, and potentially reproducing. Since most of the blossoms will be well out of your reach anyway, I wouldn't be concerned that you could over-harvest black locust blossoms.

Such superabundance, right out of reach