As part of its efforts to determine environmental and phenological states from radar imagery, the BOREAS RSS-17 team collected in situ tree xylem flow measurements for one growing season on five Picea mariana (black spruce) trees. The data were collected to obtain information on the temporal and spatial variability in water uptake by trees in the SSA-OBS (Picea mariana) stand in the BOREAS SSA. Temporally, the data were collected in 30-minute intervals for 120 days from 31-May-1994 until 27-September-1994.