The dispersal unit of wild wheat bears two pronounced awns that balance the unit as it falls. We discovered that the awns are also able to propel the seeds on and into the ground. The arrangement of cellulose fibrils causes bending of the awns with changes in humidity. Silicified hairs that cover the awns allow propulsion of the unit only in the direction of the seeds. This suggests that the dead tissue is analogous to a motor. Fueled by the daily humidity cycle, the awns induce the motility required for seed dispersal.

Background: Genome-wide homology search is inconsistent with the emerging view of bacterial genome morphology. Results: Stress-induced genome condensation proceeds through nonrandom convergence of sister chromosomes that culminates in spatial proximity of homologous sites. Conclusion: Chromosome convergence enables repair of double strand DNA breaks. Significance: Exposure to diverse stressful conditions primes bacteria to cope with detrimental DNA lesions.