Escarpment Black Cherry - Prunus serotina var. exima
Location: The island entrance to the Health Sciences Center (HSC) on the East Campus. (Map)
The genus Prunus is the classical Latin for the plum tree. This genus includes some familiar delicious fruits such as plums, cherries, peaches, apricots, apples and almonds. There are more than 200 species in this economically important group of plants. Some of the cherry trees are prized not only for their fruit, but for the wood used in furniture or cabinet making. The family name is Rosaceae. The Rose Family is a large group with more than 2900 species in 95 genera. The specific epithet, serotina, is from Latin and it means “of late” to indicate that a plant is a late bloomer, late fruit producer or some other plant characteristic that can be described as “delayed.” The variety designation eximia comes from a Latin word that means the utmost, excellent or outstanding. Prunus serotina var. eximia is an excellent plant in a landscape. It has been in cultivation in this country almost from the beginning of colonization in the 1600s.
The Escarpment Black Cherry is endemic to Texas. It grows best in well-draining soils in places like slopes and creek banks. To grow and reach its full potential of 45 to 50 feet, a moist environment is needed. The typical bark of a young Prunus species is a smooth silvery color that has gray stippling; the limbs and trunk develop a dark rough bark as they age. This is a deciduous tree with leaves that are dark green on the upper surface with a pale green under surface. The leaf shape is lanceolate with a finely-toothed (dentate) margin. The leaves are simple and are arranged alternately along the stems. There are fine hairs at the base of each leaf petiole. Wilted leaves, twigs and seeds of this plant contain a toxic compound called Prussic Acid that can be dangerous to livestock and humans if ingested. The leaves make a bright show of autumn color when their leaves turn a beautiful golden yellow.
The bloom time for this plant is March to April. The white flowers are arranged along the floral stalk in an inflorescence called a raceme (flowers along an elongated axis) that ranges from 2 to 5 inches long. The flowers each produce a one-seeded fruit called a drupe that changes from red to dark purple as it matures. The fruit is slow to mature. The fruit has been used medicinally in the past and also is used as a flavor extract. It has been called the Rum Cherry because the flavor extract was added to rum.
Some parts of the Black Cherry as mentioned above can be toxic at various times in the life cycle. The immature or green fruit can be dangerous, but not the mature fruit. The immature seeds and young twigs have more toxicity than older plant parts. However, more than 30 species of birds eat the fruit and other plant parts with no harm. Other species of wildlife also eat the fruit. Many kinds of butterflies and moths use the flower as a nectar source, and the leaves are the larva food for at least seven species of butterflies. Rabbits and deer are known to eat the twigs and leaves.
Propagation of this tree is by seeds that have been collected in the fall and cold stratified for 40 to 60 days. Another method is to use sulfuric acid to weaken the outer layer of the stone-like seed coat to enhance germination.