Project Director

Van Horn, Gene S.

Department Examiner

Bell, Becky; Ford, Dawn; O'Dea, Gregory


Dept. of Biological and Environmental Sciences


University of Tennessee at Chattanooga

Place of Publication

Chattanooga (Tenn.)


The Ranunculaceae family, also known as the Crowfoot or Buttercup family, consists of some forty genera (Gleason, 1952). The species of Ranunculaceae are most abundant in temperate regions of the Northern Hemisphere and especially diverse in the eastern part of North America. Species living near the equator grow on high mountains in cool conditions. These plants are commonly found as herbs, but may also be found as shrubs or woody vines. Their structural variations create a myriad of distinct leaf types, petal types, flower configurations, stem growth patterns, and other morphological features. The focus of this project is on the external morphology of the stamen. The unusual diversity and large size of the Ranunculaceae is the underlying cause for several reclassifications over the past 200 years. The family was first established as a taxonomic unit by A. L. Jussieu in 1789. Since that time it has been regrouped by deCandolle (1824), Bentham and Hooker (1862-67), Baillon (1863), Prantl (1888 and 1891), and Engler and Gilg (1924). The most recent reclassification of the Ranunculaceae was related to the advances of technology; this was based upon chromosome type and number (Gregory, 1941). Because of Gregory's approach to dividing the family, most botanists believe his groupings to be the most accurate. Since the family is very diverse in east Tennessee and the surrounding areas, I selected twelve genera native to this region as the focus of my study. They are the following: Aconitum Actaea Anemone Anemone Ila Aquilegia Cimicifuga Clematis Consolida Delphinium Hepatica Ranunculus Thalictrum. The purpose of this research is to compare Gregory's classifications of the Ranunculaceae with stamen characteristics because there are no previous studies dealing with stamen morphology in this family. In doing this project, I hope to find further support that Gregory's classifications are correct. His study includes nineteen genera, but I have only included the classification of the twelve genera from his paper that pertain to my research. I have studied the external features of the anther. The stamen is typically divided into an anther and a filament (Figure 1). How these parts are connected determines the type of stamen. For example, all of the stamens of the Ranunculaceae have basifixed anthers, which means the filament attaches to the anther at its base. Other morphological features used as the basis for my analysis of the family will be discussed later in the paper. There are three theories about the evolution of stamens. The first theory is widely accepted and is based upon the belief that all parts of the plant are made up of leaves that differentiate to eventually form not only cotyledons (seed leaves) and stem leaves, but floral structures such as the calyx, corolla, and sex organs. One of the theories challenging the classical theory is the telome theory, which proposes that the vascular plant is a system of branches (Figure 2). The gonophyll theory is a modification of the telome theory that attempts to satisfy the classical theory as well. In this theory, the basic structure is a leaf-borne fertile branch that evolves into parts of the plant (D' Arey and Keating, 1996).


A research project ofthis type can only be accomplished with the help of others. I would like to give credit to Mrs. Becky Bell for her willingness to help me on the SEM. Without her diligent labor and expertise during the summer of 1999, completion ofmy project would have been quite difficult. Dr. Charles H. Nelson's experience with the PAUP computer program was of great value. His assistance was much appreciated and made rapid results possible. I would also like to recognize the extremely valuable input of time, encouragement, and counsel from Dr. Gene Van Hom. His comments and suggestions during the writing of this paper were especially beneficial. Last of all, I would like to thank the University of Tennessee at Chattanooga for the Student Provost Award which helped fund my research.


B. S.; An honors thesis submitted to the faculty of the University of Tennessee at Chattanooga in partial fulfillment of the requirements of the degree of Bachelor of Science.




Ranunculaceae--Morphology; Ranunculaceae--Varieties; Stems (Botany)--Morphology


Plant Breeding and Genetics

Document Type



i, 41 leaves





Call Number

LB2369.5 .K39 1999