The Original Mystery Plant
Photo by John Nelson

Most people think tree bark is rather uninteresting. However, tree bark is rather complex in its various appearances and origin. Of course, it is only developed on woody plants. Clearly, bark varies considerably from species to species, and some types of trees are easily identified by the kind of bark they have.

The bark of this tree is certainly easily recognized. It starts out quite smooth on young twigs, but as the branches grow, the bark begins to peel and crack, thus exfoliating. Irregularly- shaped, plate- like sections fall away and typically reveal a beautiful mosaic of deeper bark that is white, tan, and often green. The bark forms prominent map- like patterns and often resembles desert camouflage.

Other than various native conifers, this species is probably the largest flowering tree in eastern North America. Its leaves are relatively large, sometimes over a foot wide, and resembling a big maple leaf.

The trees produce hundreds of tiny flowers, all compacted into a hard, rough ball that dangle from the branches. These balls tend to break apart early in the spring, disintegrating as the seeds are released. Now, this fruit type might be confused with those of the common sweetgum tree, but note that these are hard and somewhat spiny, falling on the ground intact.

Particularly large individual trees may be nearly 150' tall with a trunk diameter of 12'. Old, well- formed trees usually have an impressive, rounded crown. It's a common species that ranges from New England into the upper Midwest and south to Texas, Mexico, and northern Florida.

It is especially common on reasonably damp soils, especially within floodplain forests. It is quite adaptable and does well on high- ground sites. This tree is very popular in parks and along streets and is commonly planted. It is sometimes referred to as messy because of the falling bark, leaves, and disintegrating fruits.

In the photo, this tree's bark has a series of holes, pecked or drilled by a sapsucker, probably the Yellow- bellied variety, sphyrapicus varius. These sapsuckers don't have much sense, mindlessly pecking away and leaving an indiscriminate number of holes in a line. But there is also a second species, Sphyrapicus mathematicus, known as the "Southern counting- bird." This species is much smarter than the sapsucker and always pecks out the same number of holes.

Answer to this week's mystery plant

[Answer: "Sycamore," Platanus occidentalis]

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