Anaerobic incubation of seedlings and rhizomes reveals interspecific differences in the ability of seedlings and rhizomes of higher plants to survive under prolonged and strict anaerobiosis. Rhizomes of several species were killed by an anaerobic incubation at 22 °C for 7 d while others survived and showed normal shoot extension on return to aerobic conditions. A third group of species showed healthy and geotropically normal bud and shoot extension while their rhizomes were in the oxygen free environment. A detailed comparison of bud and shoot growth rates was made with Scirpus maritimus under aerobic and anaerobic conditions over a 14 d period. Under similar conditions four species of grass seedlings were subjected to anaerobic conditions for 2–8 d at 5°C, 15 °C and 25 °C. Seedling mortality was highest at 25 °C in all four grasses. Interspecific differences were evident. The wetland species were more tolerant of anoxia than the grasses from drier habitats.