Reflections in Nature:Sweet locust attracts bees

When I stopped by to see my friend Bob Bastion, he told me his honeybees really were working on the locust tree flowers. Bob went on to say that he had to add a super to his hives because the bees had filled all the frames.

On June 2, I wrote in my diary: “The locust trees are in full bloom.”

In past diaries, I had written that the locust trees bloomed much earlier, usually by the middle of May.

Our common locust’s scientific name is Robinia pseudoacacia. The name Robinia comes from the Frenchman Jean Robin (1550-1629), an herbalist to Henry IV, of France. Robin was credited with introducing the locust tree to Europe.

The species name of pseudo acacia is an old generic name meaning “false acacia,” which is a thorny plant growing in warm areas. The name acacia comes from the Greek word akakia, meaning “a sharp point.”

In Pennsylvania, we have three native locust trees: honey locust, water locust and the common, also known as the black locust.

Locusts have zigzag twigs that do not have a terminal bud.

The compound leaves are 8 to 14 inches long. A single leaf has up to nine (opposite) small, rounded leaflets and one terminal leaflet. These leaflets have untoothed margins and meshed veins.

The leaves are a light yellow-green in color but later darken to a soft blue-green color.

The blades of the leaflets change position in response to light, heat and air pressure. A pair of thorns usually are found at the base of the leaf stem and on smaller branches.

Locust leaves have a charm of their own. At nightfall, the leaflets droop on their long slender stalks, appearing as if the whole tree is folding up for the night. A theory that plant biologists have is that this sleep is caused by the loss of cell turgidity (sap pressure) in the secondary stalks that hold each leaflet.

It once was thought to occur because the tree was trying to avoid the loss of moisture; however, if this was the reason, the leaves would fold during the heat of the day and not at night when the air contains more moisture.

A proven reason for the nightly sleep of the locust is not known.

After the new leaves emerge in late May to early June, the flowers appear. The only non-toxic part of the plant, the flowers bloom in fragrant bunches on slender stalks that are 4 to 5 inches long. The flowers are small, with milky white petals and yellow centers.

The tree’s inner bark contains a poison that can be fatal to livestock that browse on the bark or feed upon the young shoots. However, during the winter months, the bark is eaten by cottontail rabbits without any ill effects.

Locust wood is heavy, very strong and durable when in contact with the soil. The wood was used for posts, railroad ties, mine props and ship building, back when sailing ships were made of wood. Locust nails or pegs on many old-time vessels were stronger than the strongest hulls and lasted longer.

After the American forces defeated the British on Lake Champlain during the War of 1812, the British gave their excuse for losing on the superiority of locust in America’s hastily built fleet.

The wood is extremely hard, resistant to rot and very long lasting due to the presence of tyloses and extractives in the wood. Tyloses are bulges of plant tissue that make the wood watertight, and extractives are compounds found outside the cell walls of certain plants that can provide water resistance and antifungal properties.

If dried properly, the wood has minimal shrinkage. Its extreme hardness will require the use of pilot holes when either nailing or fastening the wood. When properly fastened the first time, the stability of the wood results in little chance of nails, screws or fasteners loosening.

The seeds of the locust tree are grown in flat pods that are a dark red-brown color. By the end of winter, the sides of the pods split open, releasing the dark spotted seeds inside.

In late spring, when the flowers bloom on this impressive tree, the honey-sweet fragrance fills the air. It’s no wonder the bees are attracted to this plant.

Bower retired after 34 years as a wildlife conservation officer for the state Game Commission. He has published several books about his experiences. Questions and comments may be sent to him at 153 Redington Ave., Troy PA 16947.