The Study of Annual Rings in Lespedeza cuneata in the Tallgrass Prairie of Oklahoma

Abstract

Herb chronology is the study of the ring like growth in the secondary xylem in the taproots of perennial herbaceous plants. Not much is known about the growth rings of perennial herbaceous species, especially in the tallgrass prairie system of the Great Plains. Herbs were sampled from the Cross Timbers Experimental Range (CTER) in Stillwater, OK. Taproots of five of the most common herbaceous species of CTER were excavated. These taproots were prepared for analysis in the laboratory. The taproots were sliced into thin slices using a mini sledge microtome, and the sections were then dehydrated. Lastly, the sections were stained to differentiate between the lignified and non-lignified cells. The secondary root xylem is then examined under a microscope. Most of the species collected displayed growth rings. If these growth rings are later determined to be annual, the age of the herb can be determined, and the widths of each ring can be analyzed to determine if it correlates with yearly precipitation, average temperature, or land history such as fire.