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Reliable estimation of vegetative flow resistance calls for physically sound and readily measurable plant properties. Laboratory flume investigations were conducted to examine four reference area properties in relation to the drag, reconfiguration, and flow resistance of foliated Black Poplar twigs. The experiments were novel in that three characteristic reference areas (leaf area A_L, frontal projected area under flow A_P, and still-air frontal projected area A₀) as well as the foliage–stem reference area ratio (A_L/A_S) were evaluated. The drag forces were simultaneously measured for up to eight specimens in a plant stand at both partly and just submerged conditions. Due to the high A_L/A_S of the twigs, leaves contributed 74–98% of the total drag at mean velocities of 0.1–0.9m/s. Both the partly and just submerged poplars had similar A_P and drag per characteristic reference area. Thus, the derived parameter values could …