The power of flow cytometry in field plant research may be greatly enhanced by analysis of nonfresh tissues. Previous attempts to use chemical fixatives, however, received only little attention because of protocol complexity and limited time, after which successful assays were achieved. This unit describes simple and rapid procedures for relative nuclear DNA content estimation in dehydrated tissues of vascular plants by DAPI flow cytometry. Histograms with reasonable resolution can be obtained in several-year-old specimens. The approach here is particularly suitable for reliable determination of DNA ploidy level, although detection of small variation in nuclear DNA content is also possible in many cases. Retrospective ploidy inference in silica-dry or herbarium vouchers and simplified transport of plant material from remote areas are among the principal benefits for plant biosystematics, ecology, and population biology.