An improved oriented strand board which comprises at least one inner or core layer and two exterior or face layers, each of the layers comprising strands of a wood product mixed with an appropriate binder, at least a portion of the wood product being replaced with stems of a plant, the stems preferably being oriented in the same direction as the strands of the wood product. Preferably, the plant stems are flax stems or soybean stems or a mixture of flax and soybean stems.