Dry or fresh plant tissue is disrupted and then lysed in a special buffer containing detergent. Proteins, polysaccharides, and cellular debris are subsequently precipitated. Contaminants are further removed by isopropanol precipitation of DNA. Binding conditions are then adjusted. The sample is then applied to a spin column and centrifuged. DNA binds to the silica membrane while contaminants such as proteins and polysaccharides are efficiently removed by two wash steps. Purified DNA is eluted in a small volume of low ionic strength buffer or water.