Systematic screening of bryophytes for antitumor agents

References are made to cytotoxic and/or antitumor compounds that have been isolated ansamitocin P-3 from Claopodium crispifolium (Hook.) Ren. & Card. and Anomodon attenuatus Hueb., or an associated actinomycete, and ohioensins and pallidisetums from Polytrichum spp. Several hundred collections, which have been obtained from temperate regions of North America during 1990 and 1991, are currently being screened in new bioassays; active sesquiterpene lactones have been recently isolated from species of Porella. The methodologies of collecting and screening bryophyte samples are discussed with consideration to costs based on expected number of samples that might be collected in a day, the diversity in the collections as related to phytogeography and vegetation types, and the bryophyte cover that is vanishing in many forest regions of the United States. The difficulties in obtaining large collections for isolation of active agents are also discussed by examplerecollection of Claopodium crispifolium.