Cucumber Magnolia – Indiana Woodland Stewards

By: Megan Crecelius

Most of the time when we hear people talk about magnolias, we think of southern states and the brilliant flowers of the southern magnolia (Magnolia grandiflora, a fitting species name indeed!) or of the many ornamentals planted in yards. However, Indiana is home to two native species of magnolias’ – cucumber magnolia (Magnolia acuminata) and umbrella magnolia (Magnolia tripetala). Though we are home to these two species, that doesn’t mean they will be easy to find. While ornamentals can be found across the state in homeowners landscaping, forest stands of native magnolias are uncommon in Indiana. Umbrella magnolia is currently known of in two locations in Crawford County and cucumber magnolia is currently known in a handful of locations in two counties in southern Indiana – Clark and Washington.

The cucumber magnolia is the most cold-hardy magnolia in the United States. According to Charles C. Deam in his Trees of Indiana book (1931, p. 166), cucumber magnolia was found from the “north shore of Lake Erie, western New York, eastern Ohio, southern Indiana, southern Illinois, and along the Appalachian Mountains to southern Alabama, and west to Arkansas. It doubtless occurred in all or nearly all of the counties in southern Indiana south of a line drawn from Richmond to Vincennes. It no doubt was extremely local.” Deam goes on to describe a few encounters with local “pioneers” on their observations, “a pioneer 81 years old who always lived in Washington County told me that there were two trees on his farm near Pekin, and they were the only two trees he knew of in the vicinity. The trees were popular because the neighbors came for the fruit to put into whisky for making bitters, which were specific for many ailments. I have seen only a shrub on the Clark County State Forest” (Deam 1931, p. 166). Could one of the larger trees that was recently rediscovered at Clark State Forest have been the shrubby individual that Deam had encountered?

The DNR first located cucumber magnolia on a 35-acre section of Jackson-Washington State Forest in the early 1980’s. This area was formally dedicated as Indian Bitter Nature Preserve in 1986. Since the dedication of Indian Bitter Nature Preserve, three more populations of the cucumber magnolia have been located within Indiana’s State Forests. In 2023, these three populations were nominated to be designated as High Conservation Value Forest areas. After going through a committee review, all three locations are now within the DNR Division of Forestry’s Cucumber Magnolia High Conservation Value Forest area and are being specifically managed for the cucumber magnolia.

Cucumber magnolia is a rather fast-growing tree that takes about 25 years to flower and can live up to 150 years. It is relatively easy to identify in Indiana since we have so few species that look similar. The large, dull green leaves are smooth on top and somewhat hairy and pale below. The alternately arranged leaves are six to ten inches long, entire, and egg-shaped. The tips are pointed, while the bases are round to flat The buds of cucumber magnolia are distinctly dull yellowish in color and densely pubescent, somewhat shaped like a tulip poplar bud (they are in the same family – Magnoliaceae), about one inch long. Twigs of all magnolias are rather unique in the fact that they have stipules (leaf-like bracts) that attach to the petiole and twig. These stipules fall off during the growing season, leaving behind a stipule scar that wraps around the twig at the node. Cucumber magnolia flowers are rather small compared to others, at only about 1 inch wide with six green-yellow petals that are two to three inches long, making them very easily overlooked. Flowers sit upright and terminal at the end of the branches. The fruits also sit upright and are the same length as the flower petals. Immature fruit is green and malformed looking. Some say it resembles a cucumber, hence the common name. However, that seems to be a bit of a stretch even for my imagination. The fruit turns a bright red when it matures and splits open along its seams to expose bright red seeds that are hanging on by a short, fine thread like “umbilical” called a funiculus. The bark of cucumber magnolia has narrow ridges, divided by long fissures, somewhat like white ash, or a cross between tulip poplar and white oak bark.Bud and twig from cucumber magnolia.

Pawpaw (Asimina triloba) is about the only other species that might get confused with cucumber magnolia. However, a quick crush of a leaf will let you know as pawpaw emits a foul odor when crushed. The buds of pawpaw are also a darker brown color, resembling the tip of a paintbrush, and more pointed than the buds of the cucumber magnolia.

While many of our rare, threatened, and endangered species are sensitive to disturbances, there are several species, such as the cucumber magnolia, that thrive on disturbance. The United States Department of Agriculture (USDA) describes cucumber magnolia as a light loving species that “sprouts readily” and responds well to forest stand management (FSM). It has been noted that the “reproduction of cucumber tree in the forest is scarce because of the destruction of seed by birds and rodents, high susceptibility of the seedlings to freezing, and the exacting conditions required for germination” (USDA). Habitat fragmentation, habitat loss, and small population sizes have been noted as the most common threats as well as sensitivity to drought conditions. All of these issues can lead to a lack of cross-pollination, gene exchange, and seed dispersal. Cucumber magnolia was placed on the endangered species list in Indiana in 1984 and is currently listed by the Indiana DNR as critically imperiled (S1) and State Endangered (SE).Maturing fruit and leaf from cucumber magnolia.

 Elena Crosier, property manager of Clark State Forest measuring the diameter of a cucumber magnolia during a 2023 inventory of the population.

Megan Crecelius began her career with the Division of Forestry in February of 2016, working on the Forest Inventory and Analysis/Continuous Forest Inventory crew. She transitioned to forest ecologist in October of 2022. Megan completed her Bachelor of Arts with an emphasis in ecology and conservation biology from Franklin College and a master’s from Ball State University in Botany.