A tree with long, dangling seed pods presents an identification puzzle because the term “long” applies to the fruits of several common species. These structures can range from six inches to over two feet, varying from thin, pencil-like tubes to thick, leathery pouches. These distinctive pods often persist on the tree through the winter, making them a prominent feature when leaves are absent. Correct identification requires considering the specific shape and texture of the pod, along with other physical characteristics of the tree itself.
Common Trees with Distinctive Long Pods
One of the most widely recognized trees for its impressive pods is the Catalpa, often called the cigar tree. The fruit is a slender, cylindrical capsule resembling a long, thin cigar, typically measuring 10 to 20 inches in length. These capsules remain on the branches through the winter, starting green and maturing to dark brown. They eventually split open to release numerous flattened seeds equipped with papery, fringed wings for wind dispersal.
The Honey Locust produces flat, often twisted, brown or reddish-brown legumes that can reach lengths of 7 to 18 inches. The pod is leathery and contains seeds separated by a sweet, flavorful pulp, which earned the tree its common name. The pods ripen in the fall and may be observed on the tree or scattered on the ground throughout the winter. Many thornless and podless cultivars of this species are used in urban landscaping.
The Kentucky Coffeetree is also a member of the legume family. Its pods are shorter and much thicker than the others, typically 5 to 10 inches long and up to three inches wide, with a robust, dark brown, bean-like appearance. These pods have a leathery surface and contain large, hard seeds, which early settlers once roasted as a coffee substitute. The pods are persistent, often remaining attached to the branches until the following spring, aiding in winter identification.
Identifying Features Beyond the Pod
To confirm identification, examine characteristics beyond the fruit, particularly the leaf structure and bark texture. The Catalpa tree is easily distinguished by its large, simple, heart-shaped leaves, meaning they are undivided. These leaves are arranged oppositely or in whorls of three on the twig, a rare pattern among deciduous trees. The mature bark is typically gray or reddish-brown and separates into scaly ridges with irregular fissures.
Both the Honey Locust and the Kentucky Coffeetree, being in the pea family (Fabaceae), have compound leaves, but they differ significantly in size and complexity.
Honey Locust
The Honey Locust has leaves that are either singly (pinnately) or doubly (bipinnately) compound, with tiny leaflets often less than an inch long. Its mature bark tends to be gray-brown with long, vertical, scaly plates.
Kentucky Coffeetree
The Kentucky Coffeetree has one of the largest leaves of any native North American tree, being doubly compound and measuring up to three feet long and two feet wide. Its bark is highly distinctive, appearing dull grayish-brown with deep fissures and scaly ridges that often curl outward in a flaky manner.
Flowers
When flowers are present in late spring, the Catalpa produces showy, white, bell-shaped blooms with yellow and purple markings. In contrast, the Honey Locust and Kentucky Coffeetree have much less conspicuous greenish-yellow flowers.
The Biological Purpose of Seed Pods
The long, hard seed structures produced by these trees are botanically classified as dry fruits. These fruits serve the dual purpose of protecting the developing seeds and assisting in their dispersal.
A key botanical distinction exists between the fruits of the Catalpa and the two locusts. The Catalpa produces a true capsule, a dry fruit that develops from a compound ovary and splits open along multiple seams to release its contents. Conversely, the Honey Locust and Kentucky Coffeetree produce legumes, which are dry fruits that develop from a single carpel and typically split along two seams.
Dispersal Strategies
The Catalpa capsule, with its small, flat, winged seeds, is adapted for anemochory, or wind dispersal. When the cigar-like capsules dry and split open, the seeds are carried away by the wind.
The robust, thick-walled pod of the Kentucky Coffeetree is adapted for megafaunal dispersal by large animals. The seeds are protected by an extremely tough seed coat, which historically required passage through the digestive system of large, now-extinct mammals, such as mammoths or giant ground sloths, to allow germination. The Honey Locust’s long, sweet-pulped pods were also likely part of this megafaunal dispersal system, but the pods also drop to the ground, allowing gravity and water to move the seeds.