Are slackers a drag on the rest of us? It makes sense because those who produce (‘‘co-operators’’) benefit everyone, whereas those who don’t produce (‘‘cheats’’) get a free ride. In yeast, for instance, most strains are co-operators, secreting an enzyme called invertase that converts sucrose into the more efficiently metabolized glucose. However, about a tenth of strains are cheats that do not ...

Bromus sect. Triniusa is revised in Khorassan based on the new taxonomic concepts of Bromus danthoniae complex group and a remarkable herbarium material collected from Khorassan (Kopetdagh, northeastern Iran), as the main center of its diversity. Bromus turcomanicus, a narrow endemic species in central Kopetdagh hitherto known only from the type locality in southern Turkmenistan, is newly recor...

Chromosome morphometry and nuclear DNA content are useful data for cytotaxonomy and to understand the evolutionary history of different taxa. For the genus Bromus Linnaeus, 1753, distinct ploidy levels have been reported, occurring from diploid to duodecaploid species. The geographic distribution of Bromus species has been correlated with chromosome number and ploidy level. In this study, the a...

Bradley N. Johnson Tami L. Stubbs Land Management and Water Conservation Research Unit, USDA Agricultural Research Service, 215 Johnson Hall, Washington State University, Pullman, WA, 99164-6421 Pseudomonas fluorescens strain D7 (P. f. D7; NRRL B-18293) is a root-colonizing bacterium that inhibits downy brome (Bromus tectorum L. BROTE) growth. Before commercialization as a biological control ag...

We investigated the effects of chemical variation in thyme (Thymus vulgaris L.) on its interactions with competitors, herbivores, and herbivore predators. Four different thyme monoterpene phenotypes (chemotypes) were grown in a 4x2x2 factorial of chemotype, caging (sham half-cages vs. full cages), and competition (control vs. the grass Bromus madritensis L.). Cages reduced numbers of arthropod ...