XVI International Botanical Congess

Nostoc species were isolated from the soils of the eastern portion of the Mojave Desert. Examination of over 30 strains revealed the presence of at least 8 distinct morphotypes based on cell, akinete, and heterocyst size, sheath coloration, and details of life history. Some of the strains can be assigned to common soil cyanobacterial taxa such as Nostoc commune, N. punctiforme var. popularum, and N. muscorum. However, it is evident when the strains are observed over time that they cannot be identified with confidence using the Geitlerian system of taxonomy. We suspect that the morphotypes, which maintain stable differences in culture, should be recognized as species, some of which are new to science. The morphotypes are currently being tested using molecular sequence data of the ITS region of 16S ribosomal DNA to help determine their taxonomic status.