A final concern is the size of the repeat units. This enzyme is S1 nuclease. After digestion you obtain products that only contain repeat sequences. These products are then sized to give the average, mode and range of repeat sequences. Most plants have short period interspersions of repeats and single-copy sequences.
Genome size seems related to the type of interspersion.
Plant species with long period interspersion have longer lengths of repeats than those with short period interspersion. Repeats can border other repeats of a different class as well as single-copy sequences. Sequence interspersion was analyzed in oats, barley, wheat and rye. The following page presents the different classes of sequence interspersion. Most of the single copy sequences in the genome are short in length.