The moss Tortula ruralis is an important experimental system for studying the molecular and biochemical mechanisms of vegetative desiccation tolerance in plants. EST searches have identified a cDNA Aldh7B6 encoding a turgor-responsive aldehyde dehydrogenase (ALDH7). ALDH7B6, the 516 amino acid deduced polypeptide, is more than 60% identical to homologues from the protein family ALDH7. ALDH7B6 has a predicted molecular mass of 55.1 kDa and predicted pI of 5.87. RNA blot hybridizations were used to analyze expression of Aldh7B6 in response to desiccation, NaCl, altered light levels, ABA, & UV-C. Aldh7B6 steady-state mRNA transcript levels are unchanged in response to all treatments and the gene is constitutively expressed. We propose three conserved signature sequences for ALDH7 protein members: 1) the PR-box PAPKRGEIVRQIGD (residues 83–96), 2) the catalytic box FAAVGTAGQRCTT (residues 297–309), and the C-box (residues 424–515 of the carboxy terminus). We postulate that ALDH7B6 plays an important role in the detoxification of aldehydes generated in response to desiccation-stress and propose that ALDH7 homologues are more properly described as “stress aldehyde” ALDHs.