Monday, August 30, 2010

Carolina Buckthorn

Carolina Buckthorn, Rhamnus caroliniana, is one of my favorite shrubs. Part of the attraction is the sheer beauty of the plant itself, with its large glossy leaves. The second reason has to be the fact that the plant is a rarity in Ohio.

I normally find this shrub growing on the edges of the prairie openings or as an understory plant in the cedar thickets. In one area it grows on an open ridge top. There’s evidence that the ridge top was much more closed in the past. There are old tops from large cedars that were probably cut for logs about 30 years ago and several skeletons of Redbuds that must have lived along with the cedars. Small Carolina Buckthorn now grow along with the tall grasses.

There were a couple of large Carolina Buckthorns that lived on this ridge, but they were killed by extremely cold temperatures about 20 years ago. This shrub is a southern species and the populations here are at the extreme northern limit of their range. This ten foot specimen represents a large size for this area. I would try a couple of these as landscape shrubs around the house, but I know they will suffer the loss of their top growth every few years.

Where once there was one large shrub, there are now dozens of smaller plants. The short plants are usually protected by a covering of snow during the coldest part of the winter. Once they reach a height that exceeds the typical snow levels, the top growth suffers frequent die backs. Only a few of the hardier plants seem to survive to get any real height.

The dry, rocky conditions in which the Carolina Buckthorns grow doesn’t seem to have any adverse impacts on the plant. Even during the hottest and driest of summers, the shrubs present a perfectly healthy appearance.

Even though the population itself seems healthy, there are always some individuals that show signs of disease. Several of the little plants on this ridge top show signs of canker growth that is probably the result of some fungus infection. It makes for some odd shaped plants when you add disease damage to that already inflicted by the weather. Even under ideal conditions, these diseased individuals would probably never grow large enough to produce fruit.

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