The Original Mystery Plant
Dr. John Nelson

Photo by John Nelson

Right now my plant taxonomy class has the title Spring Flora. By the end of the semester, there are flowers everywhere, but right now, it's still winter. In a way, it's good, because there is plenty of botany to discuss without being distracted by all those silly, fervid flowers. For a few moments, let's talk about twigs. Remember that these winter- time twigs are still living.

Twigs of deciduous tree species in the winter don't have any leaves, but there are several other features that bear worth studying.

It's easy to figure out the leaf arrangement even when the leaves have fallen by recognizing the pattern of leaf scars. Within each leaf scar will be one or more, usually prominent, vascular bundle scars in some pattern. This indicates the arrangement and number of strands of vascular tissue that supplied each leaf's blade before it fell off.

Lateral buds, present at each leaf scar, hold a wealth of information. Some are prominent, some cryptic, and like the terminal buds, located at the end of the twig, they are often covered with scales. Lenticels are corky dots on twigs that are sometimes well expressed, sometimes absent, depending on the species.

The twigs of our Mystery Plant are shiny and reddish or sometimes somewhat silvery. The leaf scars and the leaves are obviously alternate and presented one at a time at a leaf node.

Whitish lenticels are commonly present but not always. One of the most memorable attributes of these twigs is their aroma. Upon scratching and sniffing the surface of the leaf, the resulting smell is a prominent scent of cyanide or bitter almond.

Interestingly, these plants are somewhat toxic to horses and other livestock especially if the foliage has been damaged. Broken, leafy branches of this tree at the edge of a pasture can be dangerous if falling or leaning over the edge of the fence. There have been a number of cases of livestock poisoning from this plant.

This species is a very common tree, found throughout the eastern half of the United States. It commonly grows on high ground and often colonizes disturbed areas and fields. The trees are usually small, but in some protected areas of the Allegheny Mountains, they may attain a height of nearly 100'.

The wood is fine grained and attractive, and large trees are valued for furniture and as a source of veneer. Large trees commonly have very handsome, dark bark, rough and checkered. Unlike its many relatives, its flowers appear in the spring after the leaves have unfolded rather than before.

Each flower bears five bright white petals that are arranged in slender racemes. In the late summer, the flowers produce small, black cherry- like fruits that are eaten by a variety of birds and wildlife species.

Answer to this week's mystery plant

[Answer: "Black cherry," Prunus caroliniana]

Dr. John Nelson is the curator of the USC Herbarium.

To learn more about the Herbarium, call 777-8196. The

department also offers free plant identification.

www.herbarium.org