Presents an outline of current knowledge relating to the response of radicles to a directional source of water (hydrotropism). New techniques are described that may be used in biology classes to demonstrate the hydrotropic response in plants. (JR)

A three-point linkage system in tomatoes is used to explain concepts of gene mapping, linking and statistical analysis. The system is designed for teaching the effective use of statistics, and the power of genetic analysis from statistical analysis of phenotypic ratios. (Author/SA)

A simple, low-cost experimental system can be used to demonstrate the "in vivo" effects of barbituates on seed germination and seedling growth behavior in different plant species. Lipid solubility and concentration of individual barbituates both affect the response. List of materials needed, procedures used, and typical results obtained are…

Describes the commercial applications of hydroponics, and then outlines ways in which this soilless plant culture method can be used in the science classroom and laboratory. Gives directions for making a suitable growth solution, and suggests appropriate student experiments involving hydroponics. (JR)

Several simple experiments illustrating how the light regime affects the final form of dog's mercury (Mercurialis perennis) are provided. These experiments, which can also be done with other plants, focus on differences in the anatomy, morphology, and physiology of sun and shade leaves. (JN)

A brief summary of the effects of light on plant germination, growth and development, including photoperiodism and pigment formation, introduces 18 experiments and demonstrations which illustrate aspects of these effects. Detailed procedures for each exercise are given, the expected results outlined, and possible sources of difficulty discussed.…

Discusses fern life cycle and basic techniques for culturing fern gametophytes in the classroom. Also discusses investigations into the reproductive biology of ferns and into the early development of gametophytes. (JN)

Describes the analysis of dandelion peduncle growth based on peduncle length, epidermal cell dimensions, and fresh/dry mass. Methods are simple and require no special apparatus or materials. Suggests that limited practical work in this area may contribute to students' lack of knowledge on plant growth. (Author/DH)

Describes several simple and inexpensive experiments designed to facilitate the study of normal and abnormal morphogenesis in the biology laboratory. Seedlings of the common garden pea are used in the experiments, and abnormal morphogenesis (tumors) are induced by a virulent strain of the crown-gall organism, Agrobacterium tumefaciens. (JR)

Activities that use dandelions to show the phenomena of geotropism and autotropism are described. Directions for collecting the stalks and observing the gravitropic response are included. The topics of lag time and bending rates, autotropism, growth rate changes, presentation time, and gravity detection are discussed. (KR)