For 21 study sites in the Acadia Forest Experiment Station, near Fredericton, New Brunswick, 34 common understory species were studied to determine the depth of underground plant organs capable of growing shoots. Depth of these plant parts tended to be species specific. These depth data, together with a knowledge of the sprouting ability of the underground organs, were used to postulate which species would survive fires of varying intensities. Most species found in the litter layer or in the F and H layer of the forested study sites would be susceptible to fires of low intensity. Rubus canadensis, Kalmia angustifolia, Vaccinium myrtilloides, Pteridium aquilinum, and Viburnum cassinoides would probably survive severe fires because the organs capable of reproduction were found in the mineral soil. In the bog study sites, Vaccinium oxycoccos, Andromeda glaucophylla, Kalmia angustifolia, Chamaedaphne calyculata, Ledum groenlandicum, and Rhododendron canadense would probably survive severe fires because the organs capable of vegetative reproduction were found 25 cm below the surface of the bog.